Preparation method of high-tap-density chemical manganese dioxide and application of high-tap-density chemical manganese dioxide in battery

Abstract

The invention belongs to a new energy material preparation technology, and particularly relates to a preparation method of high-tap-density chemical manganese dioxide and application of the high-tap-density chemical manganese dioxide in a lithium ion battery. The chemical manganese dioxide is obtained by carrying out one-step reaction on divalent manganese salt and an oxidizing agent at proper temperature and pH, the obtained chemical manganese dioxide is in a gamma crystal form, the tap density is greater than 2.38 g / cm < 3 >, the morphology is spheroidic, the purity is greater than 97%, and the impurity content reaches the industrial standard. Compared with a preparation method in the prior art, the preparation method is simple, low in cost and suitable for large-scale production, and the obtained manganese dioxide is high in tap density, good in crystallinity and excellent in electrochemical performance.

Description

Technical Field

[0001] The invention belongs to the field of new energy material preparation technology, and in particular relates to a method for preparing chemical manganese dioxide with high tap density and application thereof in batteries. Background Art

[0002] Lithium manganate cathode materials have become one of the most promising choices for lithium-ion battery cathode materials in applications such as electric vehicles and portable electronic devices due to their stable spinel structure, high voltage platform, simple synthesis process and relatively low production cost. There are a variety of lithium manganate precursor materials, and the diversity of their structure and performance significantly affects the final properties of lithium manganate cathode materials. Manganese dioxide (MnO2) is one of the most commonly used precursors in the preparation of lithium manganate cathode materials.

[0003] Depending on the preparation method, manganese dioxide can be divided into electrolytic manganese dioxide (EMD) and chemical manganese dioxide (CMD). EMD has a high manganese content, low polarization characteristics, and excellent electrochemical properties. It is suitable for large-scale production and is the main source of manganese oxide positive electrode materials. However, the production cost of EMD is high, the production equipment requirements are strict, and the particle morphology is uncontrollable. In addition, the impurities (such as Na, S ions) in EMD are high, and these impurities may increase the electrochemical impedance and affect the battery performance.

[0004] In contrast, the synthesis process of chemical manganese dioxide (CMD) is relatively simple, its performance is close to that of EMD, and it has certain adjustability in pore structure and crystal morphology, which provides a broad research space for optimizing the structure and electrochemical performance of lithium manganese oxide positive electrode materials. However, the current production cost of CMD at home and abroad is relatively high, and the tap density is low, which does not meet the conditions for large-scale production. Therefore, exploring the effects of different types of manganese dioxide on the performance of lithium manganese oxide positive electrode materials and optimizing the preparation process of manganese dioxide are of great research significance for improving the comprehensive performance of lithium manganese oxide materials.

[0005] Based on the above purpose, the prior art 1 (an industrial preparation method of lithium manganate positive electrode material for lithium ion battery CN 105016394A) uses manganese sulfate, ammonia water, magnesium sulfate and sodium carbonate as raw materials, adds them into a reactor at the same time, and stirs them at high speed in a nitrogen atmosphere to obtain spherical manganese carbonate; the prepared manganese carbonate is thermally decomposed at 600°C to prepare spherical chemical manganese dioxide with a density of 1.99g / cm 3 The technology then mixes the chemical manganese dioxide with lithium carbonate, and then calcines it at high temperature in an oxygen-rich atmosphere to obtain a doped lithium manganate compound; the doped lithium manganate compound is coated with titanyl sulfate and then fired back; the fired materials are assembled into a button-type half-cell, and the current density is 0.5 mA / cm 2The charge and discharge test was carried out under the conditions of , and the reversible specific capacity was 98.8mAh / g. It can be found that the process route for preparing chemical manganese dioxide by this technology is relatively long. It is necessary to prepare manganese carbonate by coprecipitation first, and then prepare chemical manganese dioxide by sintering process. Nitrogen needs to be introduced during coprecipitation to prevent oxidation of manganese. Oxygen needs to be introduced during the calcination process to provide an oxygen-rich atmosphere. The process route is long, the equipment requirements are high, and the raw material and process costs are increased. The tap density of chemical manganese dioxide prepared by this technology is 1.99g / cm 3 , close to but not reaching the industry requirements (tap density greater than 2.0g / cm 3 ), and the tap density of electrolytic manganese dioxide in the industry has reached 2.3g / cm 3 The lithium manganese oxide material obtained by calcining chemical manganese dioxide prepared by this technology has low reversible specific capacity and poor cycle retention rate.

[0006] Prior art 2 (a method for preparing high-purity chemical manganese dioxide CN 116553618 A) reacts the manganese sulfate solution obtained after the impurity removal process with an alkaline solution such as ammonia water or sodium hydroxide to obtain a manganese hydroxide solid, and at the same time adds an oxidant such as hydrogen peroxide, sodium persulfate or potassium persulfate to oxidize the divalent manganese in the manganese hydroxide to tetravalent manganese, and then roasts the product to obtain chemical manganese dioxide. It can be seen that the technical process is relatively cumbersome, and chemical manganese dioxide cannot be directly prepared in one step, and the prepared product has not been tested for tap density, scanning electron microscopy and electrochemical properties.

[0007] Prior art 3 (a method for preparing chemical manganese dioxide with high apparent density CN 109205678 A) Manganese carbonate and crude manganese dioxide are mixed and stirred in water, and then calcined. The obtained product is further mixed and stirred with manganese carbonate in water, and calcined again. The reaction is repeated twice to obtain a product with a density greater than 1.9 g / cm 3 The process is too complicated and not suitable for large-scale production, and the cost is high.

[0008] Based on the above analysis, a method for preparing high-purity chemical manganese dioxide with low cost, simple process, high tap density and suitable for large-scale production is needed in the art. Summary of the invention

[0009] Based on the above analysis, this application provides a method for preparing chemical manganese dioxide with high tap density and its application in batteries. Chemical manganese dioxide with high tap density can be prepared through a one-step reaction, which effectively solves the pain points of the current electrolytic manganese dioxide production cost being high and the morphology being difficult to control.

[0010] To this end, the first technical solution of the present application discloses a method for preparing chemical manganese dioxide with high tap density, comprising: adding an oxidant to a divalent manganese salt solution, controlling the pH to 2-3, conducting an oxidation reaction, and washing the reaction product with deionized water.

[0011] Furthermore, the divalent manganese salt is prepared into a salt solution to participate in the reaction, and the Mn concentration in the solution is 110-140 g / L.

[0012] Furthermore, the added mass ratio of divalent manganese to the oxidant in the manganese salt is 0.73-1.06.

[0013] Furthermore, the reaction temperature is 55-80°C.

[0014] Furthermore, the pH is adjusted using an alkaline solution.

[0015] Furthermore, the oxidant is any one of potassium permanganate, sodium chlorate, hydrogen peroxide, and ozone.

[0016] Furthermore, during the reaction, chemical MnO2 with a mass of 0.5% of the mass of the divalent manganese salt is added as a reaction seed.

[0017] And the high tap density chemical manganese dioxide prepared according to the above preparation method and its application in batteries as a precursor of lithium ion positive electrode material.

[0018] The beneficial effects of the present invention are as follows: the present invention provides a method for preparing chemical manganese dioxide with high tap density, wherein the chemical manganese dioxide is obtained by reacting a divalent manganese salt and an oxidant at a suitable temperature and pH in one step, and the obtained chemical manganese dioxide is a γ crystal form with a tap density greater than 2.38 g / cm 3 The morphology is spherical, the purity is greater than 97%, and the impurity content meets the industry standard. Compared with the preparation method of the prior art, the preparation method of the present application is simple, low-cost, suitable for large-scale production, and the obtained manganese dioxide has high tap density, high peak strength, good crystallinity and excellent quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is the XRD result diagram of high tap density manganese dioxide in Example 1;

[0020] Figure 2 This is the SEM result of high tap density manganese dioxide in Example 1;

[0021] Figure 3 This is a graph showing the particle size test results of high tap density manganese dioxide in Example 1. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solution of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Unless otherwise specifically stated, the relative arrangement of the parts and steps set forth in these embodiments, numerical expressions and numerical values ​​do not limit the scope of the application. The technology, method and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, method and equipment should be considered as a part of the authorization specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0024] The first embodiment of the present application discloses a method for preparing chemical manganese dioxide with high tap density, comprising: adding an oxidant to a divalent manganese salt, controlling the pH to 2-3, performing an oxidation reaction, and washing the reaction product with deionized water.

[0025] In this embodiment, the divalent manganese salt is a divalent metal manganese salt such as manganese chloride, manganese sulfate, manganese nitrate, etc., which is prepared into a salt solution to participate in the reaction, and the Mn concentration in the solution is 110-140 g / L.

[0026] In this embodiment, the oxidant is an oxidizing substance such as hydrogen peroxide, sodium permanganate, oxygen, ozone, etc., which can oxidize divalent manganese into tetravalent manganese.

[0027] In this embodiment, the pH of the reaction is adjusted using an alkaline solution, such as sodium hydroxide, ammonia water, potassium hydroxide, etc.

[0028] In this embodiment, it is also necessary to add a trace amount of chemical MnO2 into the reaction container in advance as a reaction seed to accelerate crystallization and nucleation.

[0029] In this embodiment, after the reaction is completed, the reaction product is placed in a deionized water solution 5 times the mass of the reaction product, stirred and washed at 60°C, filtered, and the filtered particles are dried to obtain chemical manganese dioxide with high tap density. This application realizes the one-step preparation of high tap density γ-MnO2 in a single reactor through the synergistic effect of thermodynamic regulation and kinetic control, and simultaneously realizes the production of Mn 2+ Efficient oxidation and dense growth of γ-MnO2. When the pH of the reaction system is precisely controlled at 2-4, the oxidation potential of the system is stabilized at 0.77-1.0 V. This potential range also satisfies: ①Mn 2+ →Thermodynamic feasibility of one-step oxidation of MnO2 ② The dominant phase region of γ crystal formation. At this time, the pH regulator addition rate and the oxidant (such as NaClO3) decomposition rate are controlled to produce H + The rate reaches a dynamic equilibrium, providing a stable reaction environment for the nucleation and growth of MnO2 particles.

[0030] The preparation method and technical effects of the present application will be described in detail below in conjunction with specific embodiments.

[0031] Example 1 Preparation of high tap density manganese dioxide

[0032] In this embodiment, 200 ml of a prepared manganese sulfate solution with a Mn concentration of 121.40 g / L was placed in a 1 L reactor, and 1.21 g of chemical MnO2 was added as a reaction seed. The temperature of the reaction system was set to 65 ° C, the speed of the stirring rod of the reactor was 125 rpm, and an oxidant was added to the reactor through a cross-flow pump to remove Mn. 2+ Oxidized to MnO2, wherein the oxidant is 200ml, 151.75g / L sodium permanganate solution, the feeding rate is 0.8ml / min, during which alkali solution is added to the reactor through a cross-flow pump to control the pH of the reaction system to 2.30-2.50, wherein the alkali solution is 400ml, 158.4g / L sodium hydroxide solution. After the oxidation reaction is completed, the system is aged for 2h, and then the product is filtered and washed. During washing, the product is placed in a deionized water solution five times the mass of the product, the temperature is 60°C, the stirring speed is 125rpm, the washing time is 15min, and the washing is repeated 3 times. The filtered particles are dried to obtain a chemical manganese dioxide product. The tap density of the product is 2.38g / cm 3 The oxidation rate of divalent manganese in manganese chloride solution reached 99.50%, and the XRD crystal form was γ type with high peak intensity and good crystallinity ( Figure 1 ), secondary particles with spherical morphology ( Figure 2 ), the median particle size of the product is 11.95μm( Figure 3 ).

[0033] Chemical manganese dioxide and lithium carbonate were mixed in a stoichiometric ratio of Li:Mn=1.05:2, placed in a mortar for 30 minutes of mixing and grinding, the ground material was transferred to a crucible, and placed in a tube furnace for heating, the heating rate was set to 3℃ / min, calcined at 600℃ in an air atmosphere for 6h, and then calcined at 750℃ for 16h, and naturally cooled to obtain LiMn2O4 positive electrode material. LiMn2O4, acetylene black and polyvinylidene difluoride were mixed evenly in a mass ratio of 0.75:0.15:0.1, 1mlN methyl-pyrrolidone was added to form a slurry, evenly coated on aluminum foil, and then placed in an oven at 105℃ for 8h. The dried aluminum foil was cut into discs with a diameter of 16mm as the positive electrode material. Celgard 2400 polypropylene film discs with a diameter of 18mm were used as diaphragms, and metal lithium discs with a diameter of 16mm were used as negative electrode materials. The electrolyte was 1.0M LiPf6. Then it was assembled into a CR2025 half-cell for charge and discharge testing. Under the conditions of test temperature of 25°C, voltage range of 3-4.3V, and current rate of 1C, the reversible specific capacity of the material was 113.27mAh / g, and after 200 cycles of charge and discharge, the capacity retention rate was 99.56%.

[0034] Example 2 Preparation of high tap density manganese dioxide

[0035] In this embodiment, 200 ml of a prepared manganese chloride solution with a Mn concentration of 110 g / L was placed in a 1 L reactor, and 1.1 g of chemical MnO2 was added as a reaction seed. The temperature of the reaction system was set to 75 ° C, the speed of the stirring rod of the reactor was 100 rpm, and an oxidant was added to the reactor through a cross-flow pump to remove Mn. 2+ Oxidized to MnO2, wherein the oxidant is 200ml, 112.53g / L hydrogen peroxide solution, the feeding rate is 1.1ml / min, during which alkali solution is added to the reactor through a cross-flow pump to control the pH of the reaction system to 2.50-2.70, wherein the alkali solution is 400ml, 158.4g / L ammonia solution. After the oxidation reaction is completed, the system is aged for 2h, and then the product is filtered and washed. During washing, the product is placed in a deionized water solution five times the mass of the product, the temperature is 60°C, the stirring speed is 125rpm, the washing time is 15min, and the washing is repeated 3 times. The filtered particles are dried to obtain a chemical manganese dioxide product. The tap density of the product is 2.32g / cm 3 The oxidation rate of divalent manganese in the manganese chloride solution reached 99.12%, the XRD crystal form was γ type, the peak intensity was high, the crystallinity was good, the morphology was spherical secondary particles, and the median particle size of the product was 10.24μm.

[0036] Lithium carbonate, chemical manganese dioxide and nickel oxide were mixed in a stoichiometric ratio of Li:Ni:Mn=1.05:0.5:1.5, and mixed and ground in a mortar for 30 minutes. The ground materials were transferred to a crucible and placed in a tube furnace for heating. The heating rate was set to 3°C / min, and calcined at 450°C in an air atmosphere for 5 hours, and then calcined at 850°C for 12 hours. Li Ni 0.5 Mn 1.5 O4 positive electrode material. LiMn2O4, acetylene black and polyvinylidene fluoride were mixed evenly in a mass ratio of 0.75:0.15:0.1, 1 ml of N-methyl-pyrrolidone was added to form a slurry, evenly coated on aluminum foil, and then placed in an oven at 105°C for drying for 8 hours. The dried aluminum foil was cut into discs with a diameter of 16 mm as the positive electrode material. Celgard 2400 polypropylene film discs with a diameter of 18 mm were used as diaphragms, and metal lithium discs with a diameter of 16 mm were used as negative electrode materials. The electrolyte was 1.0M LiPf6. Then it was assembled into a CR2025 half-cell for charge and discharge tests. Under the conditions of test temperature of 25°C, voltage range of 3.5-4.9V, and current rate of 1C, the reversible specific capacity of the material was 131.52 mAh / g, and the capacity retention rate was 97.45% after 200 cycles of charge and discharge.

[0037] Example 3 Preparation of high tap density manganese dioxide

[0038] In this embodiment, 200 ml of a prepared manganese nitrate solution with a Mn concentration of 138.20 g / L was placed in a 1 L reactor, and 1.21 g of chemical MnO2 was added as a reaction seed. The temperature of the reaction system was set to 55 ° C, the speed of the stirring rod of the reactor was 150 rpm, and an oxidant was added to the reactor through a cross-flow pump to remove Mn. 2+ Oxidation to MnO2, wherein the oxidant is 200ml, 130.75g / L sodium permanganate solution, the feeding rate is 0.8ml / min, during which alkali solution is added to the reactor through a cross-flow pump to control the pH of the reaction system to 2.00-2.20, wherein the alkali solution is 400ml, 158.4g / L sodium hydroxide solution. After the oxidation reaction is completed, the system is aged for 2h, and then the product is filtered and washed. During washing, the product is placed in a deionized water solution five times the mass of the product, the temperature is 60℃, the stirring speed is 125rpm, the washing time is 15min, and the washing is repeated 3 times. The filtered particles are dried, and the tap density of the obtained chemical manganese dioxide product is 2.05g / cm3. The oxidation rate of divalent manganese in manganese sulfate solution reaches 98.50%, the XRD crystal form is γ-type, the peak intensity is high, the crystallinity is good, the morphology is spherical secondary particles, and the median particle size of the product is 8.95μm.

[0039] Chemical manganese dioxide and lithium carbonate were mixed in a stoichiometric ratio of Li:Mn=1.05:2, placed in a mortar for 30 minutes of mixing and grinding, the ground material was transferred to a crucible, and placed in a tube furnace for heating, the heating rate was set to 3℃ / min, calcined at 600℃ in an air atmosphere for 6h, and then calcined at 750℃ for 16h, and naturally cooled to obtain LiMn2O4 positive electrode material. LiMn2O4, acetylene black and polyvinylidene difluoride were mixed evenly in a mass ratio of 0.75:0.15:0.1, 1mlN methyl-pyrrolidone was added to form a slurry, evenly coated on aluminum foil, and then placed in an oven at 105℃ for 8h. The dried aluminum foil was cut into discs with a diameter of 16mm as the positive electrode material. Celgard 2400 polypropylene film discs with a diameter of 18mm were used as diaphragms, and metal lithium discs with a diameter of 16mm were used as negative electrode materials. The electrolyte was 1.0M LiPf6. Then it was assembled into a CR2025 half-cell for charge and discharge testing. Under the conditions of test temperature of 25°C, voltage range of 3-4.3V, and current rate of 1C, the reversible specific capacity of the material was 108.92mAh / g, and after 200 cycles of charge and discharge, the capacity retention rate was 97.56%.

[0040] Example 4 Preparation of high tap density manganese dioxide

[0041] The present invention firstly places a prepared 200L manganese sulfate solution with a Mn concentration of 121.40g / L in a 1m 3 The reactor was filled with 1.21 kg of chemical MnO2 as a reaction seed. The temperature of the reaction system was set to 70 °C, the speed of the stirring rod of the reactor was 160 rpm, and an oxidant was added to the reactor through a cross-flow pump to transfer Mn 2+ Oxidized to MnO2, where the oxidant is 200L, 151.75g / L sodium permanganate solution, the feeding rate is 1L / min, during which alkali solution is added to the reactor through a cross-flow pump to control the pH of the reaction system to 2.30-2.40, where the alkali solution is 400L, 158.4g / L sodium hydroxide solution. After the oxidation reaction is completed, the system is aged for 3 hours, and then the product is filtered and washed. During washing, the product is placed in a deionized water solution five times the mass of the product, the temperature is 60°C, the stirring speed is 150r / min, the washing time is 15min, and the washing is repeated 3 times. The filtered particles are dried to obtain a chemical manganese dioxide product. The tap density of the product is 2.48g / cm 3 The oxidation rate of divalent manganese in the manganese chloride solution reached 99.71%, the XRD crystal form was γ type, the peak intensity was high, the crystallinity was good, the morphology was spherical secondary particles, and the median particle size of the product was 14.85μm.

[0042] Chemical manganese dioxide and lithium carbonate were mixed in a stoichiometric ratio of Li:Mn=1.05:2, placed in a mortar for 30 minutes of mixing and grinding, the ground material was transferred to a crucible, and placed in a tube furnace for heating, the heating rate was set to 3℃ / min, calcined at 600℃ in an air atmosphere for 6h, and then calcined at 750℃ for 16h, and naturally cooled to obtain LiMn2O4 positive electrode material. LiMn2O4, acetylene black and polyvinylidene difluoride were mixed evenly in a mass ratio of 0.75:0.15:0.1, 1mlN methyl-pyrrolidone was added to form a slurry, evenly coated on aluminum foil, and then placed in an oven at 105℃ for 8h. The dried aluminum foil was cut into discs with a diameter of 16mm as the positive electrode material. Celgard 2400 polypropylene film discs with a diameter of 18mm were used as diaphragms, and metal lithium discs with a diameter of 16mm were used as negative electrode materials. The electrolyte was 1.0M LiPf6. Then it was assembled into a CR2025 half-cell for charge and discharge testing. Under the conditions of test temperature of 25°C, voltage range of 3-4.3V, and current rate of 1C, the reversible specific capacity of the material was 114.63mAh / g, and after 200 cycles of charge and discharge, the capacity retention rate was 99.84%.

[0043] Test Example 1 Physical Properties Test

[0044] The manganese dioxide prepared in Example 1 was tested for particle size, crystal form, etc.

[0045] Experimental method: Use a powder property tester (BT-1001) to measure the tap density of the product. Weigh 20g of MnO2 particles and put them into the measuring tube of the instrument. Set the vibration frequency to 100Hz and the number of vibrations to 800. Start the instrument to vibrate until the volume of the sample to be tested no longer decreases. Then stop the vibration and measure the volume of the particles. According to the density formula ρ = m / v (m is the mass of the MnO2 particles in g, v is the volume of the particles in cm 3 ) can get the tap density of the material. The BT-9300ST laser particle size distribution analyzer of Dandong Better Instrument Co., Ltd., China was used to test the particle size distribution of MnO2 particles. The crystal structure and phase composition of MnO2 were characterized by X-ray diffractometer (XRD, TD-3500, China) (test voltage was 35kV, test current was 30mA, scanning range was 5 to 80°, scanning speed was 5° / min). The morphology of MnO2 was characterized by field emission scanning electron microscope (FESEM, MIRA3, China). The elemental composition and specific content of the sample were accurately analyzed and confirmed using SPECTRO BLUE inductively coupled plasma emission spectrometer (ICP-OES) produced by SPECTRO Analytical Instruments, Germany.

[0046] Experimental results: XRD results are as follows Figure 1As shown, the chemical MnO2 crystal form prepared in Example 1 is a γ crystal form with high peak intensity and no impurity peaks. Among the numerous MnO2 allotropes, γ-MnO2 has a single-chain and double-chain intergrowth tunnel structure, and the tunnel unit cell grows alternately and disorderly along the c-axis direction. There are a large number of (stacking fault) defects, non-ideal ratios, vacancies, etc. in the crystal, and it has a large average tunnel cross-sectional area, so it has good Li + Diffusion characteristics and chemical reactivity. SEM results are shown in Figure 2 As shown, the chemical MnO2 particles prepared in Example 1 are composed of primary particles and spherical secondary particles, and the particle size is highly uniform. The median particle size D 50 The spherical particles form a dense stack through surface-to-surface contact, making the particle tap density reach 2.38g / cm 3 Compared with needle-shaped particles, layered particles, cubic particles and other morphologies, spherical particles can more effectively improve the density of particles and increase the energy density per unit volume of the electrode. At the same time, spherical particles have good fluidity, which can avoid the orientation arrangement problem of needle-shaped particles in electrode slurry coating and improve the uniformity of electrode thickness.

[0047] Although the content of the present invention has been described in detail through the above-mentioned implementation cases, it should be appreciated that the above-mentioned description should not be considered as limiting the present invention. After reading the above-mentioned content, it will be obvious for those skilled in the art to make various modifications and substitutions to the present invention. Therefore, the protection scope of the present invention should be limited by the attached claims.

Claims

1. A method for preparing chemical manganese dioxide with high tap density, characterized in that: include: An oxidant is added to the divalent manganese salt, the pH is controlled to be 2-3, an oxidation reaction is performed, and the reaction product is washed with deionized water to obtain a product.

2. The preparation method according to claim 1, characterized in that: The divalent manganese salt is prepared into a salt solution to participate in the reaction, and the Mn concentration in the solution is 110-140 g / L.

3. The preparation method according to claim 1, characterized in that: The added mass ratio of divalent manganese to the oxidant in the manganese salt is 0.73-1.

06.

4. The preparation method according to claim 1, characterized in that: The reaction temperature is 55-80°C.

5. The preparation method according to claim 1, characterized in that: The pH is adjusted using an alkaline solution.

6. The preparation method according to claim 1, characterized in that: The oxidant is any one of sodium permanganate, hydrogen peroxide and ozone.

7. The preparation method according to claim 1, characterized in that: During the reaction, chemical MnO2 with a mass of 0.5% of the mass of the divalent manganese salt is added as a reaction seed.

8. A chemical manganese dioxide with high tap density prepared according to the preparation method according to any one of claims 1 to 6.

9. The high tap density chemical manganese dioxide according to claim 7 and its use as a precursor of lithium ion positive electrode material in a battery.

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