A high porosity manganese dioxide material and a method for preparing the same

Abstract

The application discloses a high-porosity manganese dioxide material and a preparation method thereof. The material is composed of spherical particles, the particles have interwoven filament structures in the interior, multiple through cavities and channels are formed, the overall porosity is 60-85%, and the filament scale is less than 200 nm. The material has high specific surface area, good mass transfer performance and structural stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of manganese dioxide materials, and in particular to a high porosity manganese dioxide material and a preparation method thereof. BACKGROUND

[0002] Manganese dioxide (MnO2) is a kind of transition metal oxide material with polymorphic structure and rich oxidation state, which is widely used in batteries, capacitors, catalysts, adsorbents and other fields due to its excellent redox performance, environmental friendliness and abundant resources. In energy devices such as lithium ion batteries, zinc-manganese batteries and supercapacitors, the energy storage performance and cycle stability of manganese dioxide as an active material are closely related to its microstructure and macroscopic morphology.

[0003] In the prior art, various modification and structure control researches have been carried out to improve the performance of manganese dioxide materials. Among them, controlling the crystal phase structure (such as α, β, γ, δ type) and morphology (such as nanorod, nanoflower, hollow sphere, tubular, etc.) is considered as an effective strategy to improve the specific surface area, ion migration rate and charge storage capacity. Some researches try to synthesize porous structures through hydrothermal method, solvothermal method, coprecipitation method and other synthesis paths to improve the mass transfer efficiency and electrochemical activity of the materials.

[0004] However, the existing preparation methods often face the following problems: first, the obtained manganese dioxide materials often have dense structure, insufficient porosity or occluded pores, which limits the effective contact of reactants with active sites; second, the internal structure of the material is mainly unidirectional orientation or disordered arrangement, which leads to limited mass transfer path and large ion migration resistance; third, the particle microstructure lacks stability and is prone to structural collapse and performance degradation under long cycle or high rate conditions.

[0005] Therefore, it is urgent to develop a high porosity manganese dioxide material with highly controllable structure, strong pore connectivity and excellent structural stability, to realize the comprehensive performance improvement of the material in the fields of energy storage, electrocatalysis and the like through microstructure design and process synergistic control. SUMMARY

[0006] In view of the deficiencies in the prior art, the purpose of the present application is to provide a high porosity manganese dioxide material and a preparation method thereof.

[0007] A high porosity manganese dioxide material, which is composed of spherical particles, the internal particles contain interwoven filament structures, the filament structures form a plurality of through cavities and channels, the overall porosity of the material is 60% to 85%, the size of the particles is 10 to 40 microns, and the size of the filament structure is less than 200 nanometers.

[0008] The key of the high porosity manganese dioxide material provided by the application lies in the interwoven filament structure formed inside the particles, which has significant micro-configuration advantages. Firstly, the size of the filament structure is less than 200 nm, which significantly improves the specific surface area in unit volume, effectively exposes more active sites, and enhances the electrochemical reaction activity of the material. Secondly, the filaments are interwoven with each other, building multiple through cavities and channels, so that the material has a three-dimensional open mass transfer network, significantly shortens the ion diffusion path, and reduces the charge transfer resistance. Further, the filament network provides a flexible buffer space, which helps to alleviate the particle structure breakage in the application environment with severe volume change (such as battery charging and discharging cycle), and improves the structural stability and cycle life.

[0009] Overall, the structure of the spherical-like particles gives the material good packing characteristics and dispersion stability, which helps to form a dense and uniform particle arrangement; the particle size range of 10-40 μm is beneficial to form a multi-scale channel system while taking into account the material processability and structural stability; the overall porosity is as high as 60%-85%, which significantly enhances the material transport rate and interface contact efficiency, thereby synergistically improving the structural integrity and functional performance of the material.

[0010] Preferably, the arrangement directions of the filament structures inside the particles have an included angle therebetween, the average included angle is 30°-50°, and the standard deviation of the direction change is greater than 25°, presenting a multi-directional divergent arrangement state.

[0011] The application further controls the arrangement directions of the filament structures inside the particles, so that they have an average included angle of 30°-50° therebetween, and the standard deviation of the direction change is greater than 25°, forming a highly multi-directional divergent spatial arrangement state. In the application, the average included angle and the standard deviation of the direction change between the filament structures can be obtained by selecting multiple filament directions inside the particles after scanning electron microscope (SEM) morphology characterization of the manganese dioxide material, measuring the relative included angle by using image processing software (such as Matlab, NIS-Elements, etc.) or manually, and further calculating the average included angle and the standard deviation. The structure design breaks the limitations of traditional linear or single-axis orientation structure in mass transfer path and structural uniformity, effectively avoiding the problems of channel blockage and local stress concentration. The filaments have irregular included angles and highly dispersed directions, which is beneficial to building a three-dimensional anisotropic through channel network inside the particles, thereby realizing rapid mass transfer in all directions. In addition, the high dispersion of the angle distribution also gives the material excellent structural elasticity and anti-collapse ability, effectively improving its stability under complex working conditions.

[0012] Preferably, the filament structure has multiple fiber bundles arranged in approximately the same direction, the transverse width of the fiber bundle is 200-500 nm, and the fiber bundle is composed of at least 5 filaments with a diameter of less than 100 nm.

[0013] The present application further introduces a plurality of fiber bundles arranged in the approximate direction in the filament structure, and by forming a highly compact and cooperative grouping arrangement between the filaments, the configuration order and local mechanical support strength of the internal structure are effectively improved. Compared with the completely disordered distributed filament structure, the "filament-fiber bundle" two-level structure not only provides a more balanced cavity support framework, but also enhances the local stability and directional coherence of the pore system, which helps to form a synergistic effect in mass transfer, mechanical deformation and interface stress conduction.

[0014] The size parameters of the fiber bundle can be analyzed by scanning electron microscope (SEM) characterization images, and the transverse width and the number of filaments contained in the fiber bundle can be extracted by computer software (such as Matlab, NIS-Elements, etc.) or manual measurement method; the equivalent determination can also be carried out by other image processing or three-dimensional reconstruction methods based on the technical personnel in the art.

[0015] Preferably, the cavity surrounded by the filament structure is irregular in shape, and the equivalent diameter is between 1-3 μm, and the cavity is in continuous and through connection with the adjacent pore.

[0016] Preferably, the internal region of the particle can be divided into fiber dense area and fiber sparse area according to the difference in the number of filaments per unit area, wherein the number of filaments contained in the dense area per 1 μm2 is not less than 25, and the number of filaments contained in the sparse area is less than 10, and the area ratio of the dense area to the sparse area is 1:1-2.3.

[0017] The distribution mode of the dense area and the sparse area of the manganese dioxide material of the present application breaks the limitation of the traditional uniform arrangement structure, and the dense area as the reaction or adsorption active site concentration area is beneficial to enhance the interface reaction capacity per unit volume; the sparse area constitutes a rapid diffusion channel with high throughness and low resistance, which is helpful to realize the rapid penetration and overall uniform distribution of substances in the structure. Both of them coexist in a certain proportion, to a certain extent, forming a structure partition regulation mechanism on a microscale, realizing the multi-objective balance of specific surface area, pore openness and structural stability.

[0018] Preferably, the surface of the particle has a plurality of open through holes, the width of the through hole is 0.5-2 μm, and the through hole is in communication with the pore in the internal region of the particle.

[0019] These diffraction peaks corresponding to the crystal face reflect the preferred orientation characteristics of the manganese dioxide material under a certain crystallization mode, and reflect that the prepared material has controllable phase composition and structure sequence.

[0020] Preferably, the main diffraction peak of the X-ray diffraction pattern of the material is located at 2θ=12.2°, 18.0°, 28.7°, 36.6°, 49.9°, 60.2°.

[0021] The atlas is different from the conventional high crystallinity or block structure of commercial manganese dioxide materials such as γ-MnO2, β-MnO2, etc., and has a relatively wide peak shape and moderate diffraction intensity, which reflects that the material has a medium crystallinity and a limited stacking behavior, and is a characteristic diffraction response of low-dimensional filaments self-assembled under non-uniform stress and ordered guidance.

[0022] This diffraction characteristic indicates that the material crystal structure has a certain degree of structural distortion and low-order interval distribution, which is beneficial to form a highly porous non-dense network at the nanoscale, effectively release the lattice binding energy, and promote the rapid penetration and interfacial reaction of the reaction medium in the structure. At the same time, compared with the conventional high crystallinity MnO2, the structure provides sufficient crystal stability while avoiding problems such as blocked grain boundaries and limited ion migration path, achieving a balance between structure openness and stability.

[0023] A preparation method of a high porosity manganese dioxide material, comprising the following steps:

[0024] S1: Dissolving a manganese source salt in a deionized water and ethanol mixed solution, adding a complexing agent and a surfactant, and stirring to form a uniform precursor solution, wherein the manganese source salt is manganese sulfate or manganese chloride, and the complexing agent is sodium citrate or EDTA;

[0025] S2: Under stirring, adding an oxidizing agent to the solution dropwise, gradually increasing the pH of the solution to 5.5-7.0, and generating a brown-black gel-like precipitate, wherein the oxidizing agent is potassium permanganate or hydrogen peroxide;

[0026] S3: Transferring the precipitate to a hydrothermal reaction kettle and reacting at 100-140°C for 6-12 hours to induce the formation of α-type and δ-type manganese dioxide coexisting crystals;

[0027] S4: After cooling, taking out the product, washing with water and alcohol, and drying at 60-80°C to obtain an intermediate;

[0028] S5: Heat treating the intermediate in air or an inert atmosphere at 300-400°C for 1-3 hours to obtain the high porosity manganese dioxide material.

[0029] Preferably, in the step S2, the process of adding the oxidizing agent is divided into two stages, the first stage continuously adding 60%-70% of the amount of the oxidizing agent at a pH of 2.5-4.0, then stopping stirring and standing for 20-30 minutes, and then adding the remaining amount of the oxidizing agent while slowly adjusting the pH to 5.5-6.5.

[0030] The first-stage addition of the oxidant in step S2 facilitates the formation of primary Mn(III) / Mn(IV) nuclei at lower alkalinity and induces non-uniform nucleation of colloidal precursors, limiting the rapid growth of crystals and forming a small-sized, uniformly dispersed initial filament network framework. On this basis, the static process provides a non-convection, low-disturbance local reorganization environment, promoting the initial cross-linking and orderly stacking between filaments, and providing a morphological basis for subsequent multi-directional divergent orientation and fiber bundle formation.

[0031] The second-stage droplet addition allows the remaining oxidation reaction to proceed at a gentler gradient, further guiding the hierarchical assembly of the primary structure. This process helps to form multi-scale cavity structures between the filaments, promotes the natural differentiation of dense and sparse fiber regions inside the particle, and retains some through-pore structures on the particle surface, enabling communication between the external channels and the internal cavities.

[0032] Preferably, in step S3, the reaction system is mechanically disturbed every 30 minutes for 10 minutes within the first 2 hours after the hydrothermal reaction temperature reaches the set value; before the heat treatment in step S5, the dried product is placed in a nitrogen atmosphere for 60-90 minutes before being heated to the set temperature.

[0033] Step S3 involves periodically performing mechanical disturbance during the initial stage of the hydrothermal reaction (the first two hours after the temperature reaches the set value), with a disturbance lasting 10 minutes every 30 minutes. This disturbance strategy artificially introduces local shear and micro-convection during the nucleation-sensitive period, effectively breaking down the local enrichment and viscous regions formed by the reactants under static conditions, thereby suppressing particle agglomeration and disordered crystal growth induced by local supersaturation. This operation helps achieve dispersed nucleation and uniform growth of filamentous structures, enhancing the consistency of the microstructure within each particle.

[0034] Before the heat treatment in step S5, the dried product is allowed to stand under a nitrogen atmosphere for 60–90 minutes. This allows the product to undergo spontaneous rearrangement and desorption of adsorbed water, surface complexes, and residual organic matter before heating, effectively mitigating heat-induced structural disintegration. This standing stage provides a mild pre-destruction environment for the material, which is beneficial for the gradual release of internal stress in the filament bundles and the fixation of the microporous framework. This, in turn, inhibits pore collapse and filament breakage caused by rapid volatilization or crystal migration during heat treatment.

[0035] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in the following aspects:

[0036] This invention achieves a multi-level porous structure distribution of materials at the particle size, filament, cavity, and fiber bundle scales by constructing a microstructure composed of spherical particles containing interwoven filaments. This significantly improves the specific surface area and porosity of the material, thereby enhancing interfacial reactivity and mass transport efficiency.

[0037] The average angle between the filaments inside the particle is 30-50°, the standard deviation of the direction change is greater than 25°, and a highly multi-directional divergent state is presented, a three-dimensional anisotropic open channel network is constructed, and the collapse resistance and cycle stability of the structure are improved. Secondly, by adjusting the filament density per unit area, the dense and sparse areas are distributed alternately inside the particle, the specific surface area and channel openness are effectively balanced, and the interface reaction and diffusion process are synergistically optimized. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 A scanning electron microscope (SEM) photograph of the manganese dioxide material of Example 1 at a magnification of 500 times.

[0039] Figure 2 A scanning electron microscope (SEM) photograph of the manganese dioxide material of Example 1 at a magnification of 1000 times.

[0040] Figure 3 A scanning electron microscope (SEM) photograph of the manganese dioxide material of Example 1 at a magnification of 2000 times.

[0041] Figure 4 A scanning electron microscope (SEM) photograph of the manganese dioxide material of Example 1 at a magnification of 5000 times.

[0042] Figure 5 A scanning electron microscope (SEM) photograph of the manganese dioxide material of Example 1 at a magnification of 10000 times.

[0043] Figure 6 A scanning electron microscope (SEM) photograph of the manganese dioxide material of Example 1 at a magnification of 15000 times. DETAILED DESCRIPTION

[0044] The application will be described in detail below with reference to examples.

[0045] Example 1

[0046] The embodiment discloses a preparation method of a high-porosity manganese dioxide material, comprising the following steps:

[0047] S1. Preparation of a precursor solution:

[0048] Take 11 parts by weight of manganese sulfate (MnS04-H20, AR, purity > 98%) and dissolve it in 100 parts by weight of a mixture of deionized water and anhydrous ethanol (volume ratio 4:1) to form a light pink clear solution. Stir for 15 minutes using magnetic stirring (600 rpm).

[0049] Then add 3.2 parts by weight of sodium citrate (Na3C6H507-2H20, AR) as a complexing agent, and continue stirring for 10 minutes. After the complex is stable, add 0.8 parts by weight of sodium dodecyl sulfate, and continue stirring for 5 minutes to form a stable and uniform colloidal precursor solution.

[0050] S2. Oxidative precipitation reaction:

[0051] Under magnetic stirring (400 rpm), potassium permanganate (KMn04, AR, > 99%) is dissolved in deionized water to prepare a 0.3 mol / L oxidant solution, and a burette is used to control the dropping rate. The oxidant is added in two stages:

[0052] First stage (control nucleation):

[0053] Maintain the pH of the reaction system at 2.8 (adjust with 1M H2S04), and add the oxidant at a rate of 0.5 mL / min to a total of 65%. Keep the temperature at 25°C and continue stirring for 15 minutes to promote the gradual oxidation of initial Mn(II) to Mn(III, IV) and induce the formation of primary gelatinous precipitates.

[0054] Transition period:

[0055] Immediately stop stirring after the addition is complete, and let it stand for 25 minutes to allow the primary precipitated gel network to naturally shrink in a low disturbance state, which is conducive to the formation of primary cavities and the induction of filamentous nuclei.

[0056] Second stage (control growth):

[0057] Resume stirring (300 rpm) and continue adding the remaining 35% of the oxidant, while slowly adding 1M NaOH solution to adjust the system pH to 6.0, maintaining a pH fluctuation range of no more than ± 0.1. Continue the reaction until the solution gradually changes from deep purple red to brown black, indicating that the Mn02precursor precipitation reaction is complete.

[0058] S3. Hydrothermal treatment:

[0059] Transfer the reaction precipitate to a stainless steel autoclave lined with polytetrafluoroethylene, seal it, and place it in an oven at 120°C for 10 hours.

[0060] During the first 2 hours after the hydrothermal temperature reached 120℃, the reactor was subjected to 10 minutes of agitation every 30 minutes by an external mechanical agitation or an embedded magnetic stirring device.

[0061] S4. Washing and drying treatment:

[0062] After natural cooling to room temperature, the hydrothermal reaction product was collected by low-speed centrifugation (4000 rpm, 5 minutes), washed with deionized water for 3 times and absolute ethanol for 2 times to remove residual ions and organic impurities.

[0063] The washed sample was placed in a vacuum drying oven at 80℃ for 12 hours to obtain the intermediate powder.

[0064] S5. Heat treatment and pore structure solidification:

[0065] The dried powder was placed in a quartz boat and loaded into a quartz tube furnace. First, the system was completely inertized by passing high-purity nitrogen (99.999%) at a flow rate of 200 mL / min for 75 minutes. Then, the temperature was raised to 350℃ at a rate of 5℃ / min, and the heat treatment process was completed by maintaining the temperature at 350℃ for 2 hours.

[0066] The prepared manganese dioxide material was characterized by scanning electron microscopy (SEM). The obtained scanning electron microscope images with magnifications of 500x, 1000x, 2000x, 5000x, 10000x, and 15000x are shown in Figures 1-6 respectively. The parameters of the manganese dioxide material were measured using computer software (such as Matlab, NIS-Elements, etc.) or manually, and are shown in Table 1 below:

[0067] Table 1

[0068]

[0069] Example 2

[0070] This example discloses a method for preparing a high-porosity manganese dioxide material, comprising the following steps:

[0071] S1. Preparation of precursor solution:

[0072] 9.0 parts by weight of manganese chloride tetrahydrate (MnCl2·4H2O, AR, purity ≥ 99%) was weighed into 100 parts by weight of mixed solvent (deionized water and anhydrous ethanol in a volume ratio of 3:2). After stirring to form a light pink transparent solution, 2.8 parts by weight of trisodium citrate (Na3C6H5O7·2H2O) was added as a complexing agent, and stirring was continued for 10 minutes. Then 1.0 parts by weight of cetyltrimethylammonium bromide (CTAB) was added as a surfactant, and stirring was continued for 10 minutes to form a stable and uniform precursor solution.

[0073] S2. Oxidative precipitation reaction:

[0074] Potassium permanganate was prepared into a 0.2 mol / L oxidant solution, and a burette was used to add the oxidant at a rate of 0.3 mL / min in two stages:

[0075] First stage: adjust the pH of the system to 3.2, add 70% of the total amount of oxidant, and maintain stirring (350 rpm) for 15 minutes;

[0076] Resting stage: stop stirring and rest for 30 minutes;

[0077] Second stage: continue to add the remaining 30% of the oxidant, while slowly adding 1 mol / L NaOH solution to raise the pH of the system to 6.2, continue stirring for 5 minutes until the precipitate is completely formed, generating a brown-black gel-like precursor.

[0078] S3. Hydrothermal treatment:

[0079] The resulting precipitate was transferred to a polytetrafluoroethylene liner and hydrothermally reacted at 110°C for 12 hours. During the first 2 hours after the reaction temperature reached 110°C, the system was mechanically disturbed every 30 minutes (for 10 minutes) to promote uniform growth of the structure.

[0080] S4. Washing and drying treatment:

[0081] After natural cooling, the product was washed with deionized water 3 times and anhydrous ethanol 2 times, and the centrifugal speed was set to 5000 rpm each time. After washing, the sample was dried at 80°C under vacuum conditions for 10 hours to obtain an intermediate powder.

[0082] S5. Heat treatment and pore structure solidification:

[0083] The dried product was placed in a quartz boat and directly heated to 350°C at a heating rate of 5°C / min in an air atmosphere, and heat-treated for 3 hours to obtain the target high-porosity manganese dioxide material.

[0084] Example 3

[0085] The embodiment discloses a preparation method of a high-porosity manganese dioxide material, and comprises the following steps:

[0086] S1. Preparation of a precursor solution:

[0087] 8.5 parts by weight of manganese chloride tetrahydrate (MnCl2·4H2O, AR, purity ≥ 99%) is weighed and dissolved in 95 parts by weight of a mixed solvent (deionized water and anhydrous ethanol in a volume ratio of 3:2). After stirring to form a uniform solution, 3.0 parts by weight of disodium ethylenediaminetetraacetate (EDTA) is added as a complexing agent, and stirring is continued for 15 minutes. After the complex is stably formed, 1.2 parts by weight of cetyltrimethylammonium bromide (CTAB) is added as a surfactant, and stirring is continued for 5 minutes to form a stable precursor solution.

[0088] S2. Oxidative precipitation reaction:

[0089] Hydrogen peroxide (H2O2, 30%) is prepared into a 0.5 mol / L solution, and the dropping process is divided into two stages:

[0090] First stage: maintain the pH of the reaction system at 2.8 (adjust using 1M H2SO4), drop 65% of the total amount of oxidizing agent, and set the dropping rate to 0.4 mL / min. Continue stirring (350 rpm) for 20 minutes to generate a preliminary gel-like precipitate;

[0091] Resting stage: stop stirring after the dropping is completed, and rest for 30 minutes to form a primary gel network and promote the preliminary cross-linking of the filaments;

[0092] Second stage: resume stirring, drop the remaining oxidizing agent, and at the same time, slowly add 1M NaOH solution to adjust the pH to 6.0. Maintain stirring until the reaction is complete, and the precipitate turns into a dark brown color.

[0093] S3. Hydrothermal treatment:

[0094] The precipitate is transferred to a stainless steel autoclave, and the reaction temperature is set to 100°C. Keep the reaction for 12 hours. Within the first 2 hours after the hydrothermal reaction temperature reaches the set value, the reaction system is subjected to mechanical disturbance for 10 minutes every 30 minutes.

[0095] S4. Washing and drying treatment:

[0096] After the reaction is completed, cool to room temperature, take out the product, wash with deionized water 3 times, and wash with ethanol 2 times. Use a centrifuge at a speed of 5000 rpm. After washing, the sample is dried in a vacuum environment at 80°C for 12 hours to obtain an intermediate powder.

[0097] S5. Heat treatment and pore structure solidification:

[0098] The dried product was placed in a quartz boat, and was heated to 360°C at a heating rate of 5°C / min under an air atmosphere, and was kept at this temperature for 2 hours to obtain a final high-porosity manganese dioxide material.

[0099] Comparative Example 1 used a commercially available conventional manganese dioxide material, specifically Thermo Scientific Manganese Powder from Thermo Fisher Scientific, with a particle size of less than 10 microns and a metal purity of 99.6% (as metal).

[0100] Performance testing

[0101] The manganese dioxide material prepared in Example 1 was subjected to porosity testing by BET method, and the test results are shown in Table 2 below.

[0102] Table 2

[0103]

[0104] The above only describes the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above-described embodiments only, and any technical solutions falling within the concept of the present application shall fall within the protection scope of the present application. It should be noted that, for ordinary skilled persons in the art, some improvements and refinements without departing from the principles of the present application shall also be considered as falling within the protection scope of the present application.

Claims

1. A high porosity manganese dioxide material characterized in that, The material is composed of spherical particles, the inside of the particles contains interwoven filament structure, the filament structure forms a plurality of through cavities and channels, the overall porosity of the material is 60-85%, the size of the particles ranges from 10 to 40 microns, and the size of the filament structure is less than 200 nm. The preparation method of the high-porosity manganese dioxide material comprises the following steps: S1: Dissolve manganese source salt in a deionized water and ethanol mixed solution, add a complexing agent and a surfactant, and stir to form a uniform precursor solution, wherein the manganese source salt is manganese sulfate or manganese chloride, and the complexing agent is sodium citrate or EDTA; S2: Under stirring, drop the oxidizing agent into the solution, and the dropping process of the oxidizing agent is divided into two stages, the first stage is continuously dropped to 60-70% of the amount of the oxidizing agent under the condition of pH 2.5-4.0, then stop stirring and stand for 20-30 minutes, and then drop the remaining amount of the oxidizing agent while slowly adjusting the pH to 5.5-6.5 in the second stage, to generate a brown-black gel-like precipitate, wherein the oxidizing agent is potassium permanganate or hydrogen peroxide; S3: Transfer the precipitate to a hydrothermal reaction kettle and react at 100-140℃ for 6-12 hours to induce the formation of coexisting α-type and δ-type manganese dioxide crystals; S4: After cooling, take out the product, wash with water and alcohol, and dry at 60-80℃ to obtain an intermediate; S5: Heat treat the intermediate in air or inert atmosphere at 300-400℃ for 1-3 hours to obtain the high-porosity manganese dioxide material.

2. The high porosity manganese dioxide material of claim 1, wherein, The arrangement directions of the filament structure inside the particles have an included angle between each other, the average included angle is 30-50°, the standard deviation of the direction change is greater than 25°, and the arrangement state is multi-directional divergence.

3. The high porosity manganese dioxide material of claim 1, wherein, A plurality of fiber bundles exist in the filament structure, the transverse width of the fiber bundle is 200-500 nm, and the fiber bundle is composed of at least 5 filaments with a diameter less than 100 nm.

4. The high porosity manganese dioxide material of claim 1, wherein, The cavities surrounded by the filament structure are irregular in shape, the equivalent diameter is between 1-3 microns, and the cavities are continuously connected with adjacent channels.

5. The high porosity manganese dioxide material of claim 1, wherein, The inner region of the particle is divided into fiber dense area and fiber sparse area according to the difference of the number of filaments per unit area, wherein the number of filaments per 1 μm 2 in the dense area is not less than 25, and the number of filaments per 1 μm in the sparse area is less than 10, and the area ratio of the dense area to the sparse area is 1:1-2.

3.

6. The high porosity manganese dioxide material of claim 1, wherein, The surface of the particle has a plurality of open through holes, the width of the through hole is 0.5-2 microns, and the through hole is in communication with the channel inside the particle.

7. The high porosity manganese dioxide material of claim 1, wherein, The main diffraction peaks of the X-ray diffraction pattern of the material are located at 2θ=12.2°, 18.0°, 28.7°, 36.6°, 49.9°, and 60.2°.

8. The high porosity manganese dioxide material of claim 1, wherein: In the step S3, the reaction system is mechanically disturbed every 30 minutes for 10 minutes within the first 2 hours after the hydrothermal reaction temperature reaches the set value; and before the heat treatment of the step S5, the dried product is placed in a nitrogen atmosphere for 60-90 minutes before being heated to the set temperature.

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