A manganese dioxide composite material for a battery and a process for preparing the same

Abstract

The application belongs to the technical field of new energy, and particularly relates to a manganese dioxide composite material for a battery and a preparation process thereof. 3+ The application comprises the following steps: preparation of iron ion loaded cattail down; hydrothermal template method synthesis of beta-manganese dioxide; vacuum impregnation and calcination treatment of the precursor template. The application can induce oxygen atoms to separate from the crystal lattice to form oxygen vacancies when calcination is performed subsequently by loading Fe 2+ ions on the surface of the cattail down and doping glucose while synthesizing beta-manganese dioxide. The residual carbon generated by pyrolysis can cover the surface of the manganese dioxide and inhibit the backfilling of the oxygen vacancies. The oxygen vacancies formed after calcination can increase the storage sites of the carriers (Zn + and H ), thereby giving the subsequent manganese dioxide composite material a higher specific capacity, so that the discharge specific capacity of the manganese dioxide composite material as a battery anode is effectively increased.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new energy, and particularly relates to a manganese dioxide composite material for a battery and a preparation process thereof. BACKGROUND

[0002] With the acceleration of global energy structure transformation, electrochemical energy storage technology has become the core support for realizing efficient utilization of renewable energy. Among many energy storage systems, although traditional lithium-ion batteries have long dominated the market, their inherent bottlenecks have become increasingly prominent. On the one hand, the system based on organic electrolyte has safety hazards such as flammability and explosiveness, and may release toxic fluoride under thermal runaway conditions. On the other hand, the uneven geographical distribution of lithium resources and the rising mining cost have put continuous pressure on the economy of the battery system.

[0003] Therefore, aqueous multi-valence ion batteries have attracted widespread attention due to their intrinsic safety and cost advantages. Among them, aqueous zinc-ion batteries have high theoretical capacity, low price and abundant zinc resources. Unlike the single-electron transfer mechanism of lithium ions, zinc ions achieve charge storage through a double-electron reaction, which can provide higher volumetric energy density. However, the actual performance of this system is highly dependent on the reversible storage capacity of Zn2+ + .

[0004] At present, common positive electrode materials of aqueous zinc-ion batteries mainly include manganese-based compounds, vanadium-based compounds, Prussian blue analogues and organic compounds. Manganese-based positive electrode materials have become the most studied ZIBs positive electrode materials due to their high theoretical capacity, high voltage window, non-toxicity and abundant reserves. However, the poor intrinsic conductivity and large volume change during charging and discharging of manganese-based materials result in low capacity, short cycle life and slow reaction kinetics. SUMMARY

[0005] In order to solve the above technical defects, the application researches a preparation process of a manganese dioxide composite material for a battery. The prepared manganese dioxide composite material has high specific capacity and long cycle stability when used as a positive electrode material, and has excellent electrochemical performance.

[0006] A preparation process of a manganese dioxide composite material for a battery, comprising the following steps:

[0007] S1: preparation of iron ion loaded cattail down

[0008] After washing the cattail down, it is modified by immersing it in a 3-aminopropyl triethoxysilane solution to obtain amino-functionalized cattail down. The amino-functionalized cattail down is immersed in a FeCl3 solution prepared by mixing FeCl3, sodium citrate and deionized water, and after oscillation reaction, centrifugation, washing and drying, iron ion loaded cattail down is obtained.

[0009] S2: Hydrothermal template synthesis of β-manganese dioxide

[0010] MnSO4·H2O and (NH4)2S2O8 were added to the glucose aqueous solution under stirring until the Mn 2+ concentration of 0.2-0.3 mol / L, and then Fe ions were loaded into the cattail down to obtain a mixture, which was then transferred to an autoclave for hydrothermal reaction. After centrifugal cleaning and drying, a precursor template of oxygen vacancy loaded with β-manganese dioxide was obtained.

[0011] S3: Vacuum impregnation and calcination treatment of the precursor template

[0012] The cobalt tetramethoxyphenyl porphyrin and europium nitrate hexahydrate were mixed uniformly in anhydrous ethanol, and then the precursor template of oxygen vacancy loaded with β-manganese dioxide was immersed therein and vacuum impregnated. After being taken out and dried, it was placed in a tubular vacuum furnace for vacuum calcination. After being cooled to room temperature, it was washed and dried to obtain a manganese dioxide composite material.

[0013] Further, the preparation of the iron ion loaded cattail down in step S1 includes the following steps:

[0014] S1.1: The cattail down was immersed in an ethanol solution with a concentration of 25-30%, and then ultrasonic treatment was performed at 200-220 W and 30-35 kHz for 25-30 minutes. After being taken out, it was placed in a vacuum drying box at 60-65°C for drying to obtain cleaned cattail down. 3-Aminopropyl triethoxysilane was mixed with anhydrous ethanol at a volume ratio of 1:(15-20), and acetic acid was used to adjust the pH to 5-5.5. After hydrolysis for 20-25 minutes, a 3-aminopropyl triethoxysilane solution was obtained. The cleaned cattail down was immersed in the 3-aminopropyl triethoxysilane solution at a solid-liquid ratio of 1:(10-15) g / mL. After being stirred uniformly, it was placed at 45-50°C for 1-2 hours. After filtration, the solid residue was washed and dried to obtain amino-functionalized cattail down.

[0015] S1.2: FeCl3, sodium citrate and deionized water were mixed to prepare a Fe 3+ concentration of 0.2-0.3 mol / L, and the concentration of sodium citrate was 0.04-0.05 mol / L. The pH was adjusted to 4.5-5. Then the amino-functionalized cattail down was immersed in the FeCl3 solution at a solid-liquid ratio of 1:(15-20) g / mL, and was transferred to a constant temperature oscillator for oscillation reaction for 2-3 hours. Then it was centrifuged at 4000-5000 rpm for 10-15 minutes. After being washed, it was placed in a vacuum drying box at 60-65°C for drying to obtain iron ion loaded cattail down.

[0016] Further, the step S2 hydrothermal templating synthesis of β-manganese dioxide includes the following steps:

[0017] S2.1: Under stirring, MnSO4·H2O and (NH4)2S2O8 are added into a glucose aqueous solution with a concentration of 0.1-0.2 mol / L at a molar ratio of 1:(1-1.2) until the Mn 2+ concentration is 0.2-0.3 mol / L to obtain a manganese-glucose solution;

[0018] S2.2: The iron ion loaded cattail down and the manganese-glucose solution are mixed uniformly at a solid-liquid ratio of 1:(60-80) g / mL, and then sealed in a polytetrafluoroethylene lined stainless steel autoclave, and the hydrothermal reaction temperature is set to 140-145℃, and the time is 12-13 hours. After the reaction is completed, the reaction solution is centrifuged, the bottom precipitate is taken and added with 15-20 times the mass of anhydrous ethanol to be centrifuged again, and the precipitate is collected and dried at 80-85℃ to obtain an oxygen vacancy precursor template loaded with β-manganese dioxide.

[0019] Further, the step S3 vacuum impregnation and calcination treatment of the precursor template includes the following steps:

[0020] S3.1: 6-6.5 parts by weight of europium nitrate hexahydrate powder and 3.5-4 parts by weight of cobalt tetramethoxyphenyl porphyrin are added to 30-40 parts by weight of anhydrous ethanol to obtain a mixed impregnation solution. After stirring uniformly, 6-8 parts by weight of the oxygen vacancy precursor template loaded with β-manganese dioxide is immersed in the mixed impregnation solution, and then transferred to a vacuum impregnation tank for vacuum impregnation. After taking out, it is transferred to a blast drying oven and dried at 75-80℃ to obtain an oxygen vacancy precursor template coated with rare earth complexes;

[0021] S3.2: The oxygen vacancy precursor template coated with rare earth complexes is placed in a tubular vacuum furnace and heated to 480-500℃ at a heating rate of 5-10℃ / min under a vacuum condition of 0.1-0.5 Pa, and then held for 1-1.5 hours. After natural cooling to room temperature, it is washed with deionized water for 2-3 times, and then dried at 60-65℃ to obtain a manganese dioxide composite material.

[0022] Further, the condition of the oscillation reaction in step S1.2 is 25℃, 150-200 rpm.

[0023] Further, the centrifugal speed of the centrifugation in step S2.2 is 6000-8000 rpm, and the time is 10-15 minutes.

[0024] Further, the vacuum degree of the vacuum impregnation process in step S3.1 is 10-20 Pa, and the time is 30-35 minutes.

[0025] A manganese dioxide composite material for a battery is prepared by the above-mentioned process for preparing a manganese dioxide composite material for a battery.

[0026] The beneficial effects are: 1. The present application loads Fe 3+ ions on the surface of cattail down, and then dopes glucose while synthesizing beta-manganese dioxide, and when calcination is subsequently performed, Fe 3+ partially replaces Mn 4+ sites, at which time adjacent oxygen atoms tend to be separated from the crystal lattice to form oxygen vacancies, and glucose pyrolyzes under vacuum to generate reducing gases CO and H2, inducing oxygen atoms to be separated from the crystal lattice of the composite material to form oxygen vacancies, and the residual carbon generated by pyrolysis coats the surface of the manganese dioxide, which can inhibit the backfilling of oxygen vacancies, and the oxygen vacancies formed after calcination can increase the storage sites of carriers (Zn 2+ and H + ), thereby giving the subsequent manganese dioxide composite material a higher specific capacity, thereby effectively increasing the discharge specific capacity of the manganese dioxide composite material as a battery anode.

[0027] 2. The present application uses cattail down as a template for a hydrothermal synthesis reaction of beta-manganese dioxide to prepare an oxygen vacancy precursor template loaded with beta-manganese dioxide, and then forms porous manganese dioxide flower balls composed of flaky manganese dioxide during subsequent calcination, and the carbonized residual microcrystalline carbon of the cattail down forms a continuous conductive framework between the beta-manganese dioxide, which not only improves the conductivity of the composite material, enhances the rate performance, but also stabilizes the structural framework, and when used as a battery anode material, can maintain long-term cycle stability and greatly improve the capacity retention rate of the anode material, and has long cycle stability.

[0028] 3. The present application coats cobalt tetramethoxyphenyl porphyrin and europium nitrate on the surface of the oxygen vacancy precursor template loaded with beta-manganese dioxide by complexation through a vacuum impregnation method, and the rare earth complex-coated oxygen vacancy precursor template can further form a carbon conductive framework during calcination, and the cobalt therein can be coated and penetrated into the beta-manganese dioxide along with the molten europium nitrate, which reduces the energy band gap of the manganese dioxide, improves the conductivity of the composite material, and also stabilizes the crystal structure of the beta-manganese dioxide, further improving its electrochemical performance. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The process flow chart for preparing the manganese dioxide composite material for a battery used in the embodiments of the present application. DETAILED DESCRIPTION

[0030] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. 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 making creative efforts are within the scope of protection of the present invention.

[0031] Example 1

[0032] A manganese dioxide composite material for battery and its preparation process, such as Figure 1 As shown, the following steps are included:

[0033] S1: Preparation of iron ion loaded cattail fluff

[0034] S1.1: Immerse the cattail fluff in a 25% ethanol solution, then perform ultrasonic treatment at 200 W and 30 kHz for 25 minutes, remove and dry in a vacuum drying oven at 60°C to obtain cleaned cattail fluff, mix 3-aminopropyltriethoxysilane and anhydrous ethanol in a volume ratio of 1:15, adjust the pH to 5 with acetic acid, and hydrolyze for 20 minutes to obtain a 3-aminopropyltriethoxysilane solution, immerse the cleaned cattail fluff in the 3-aminopropyltriethoxysilane solution at a solid-liquid ratio of 1:10 g / mL, stir evenly, and let stand at 45°C for 1 hour, filter and collect the solid residue, wash and dry it to obtain amino-functionalized cattail fluff;

[0035] S1.2: Mix FeCl3, sodium citrate and deionized water to prepare Fe 3+ The concentration of FeCl3 solution was 0.2 mol / L, and the concentration of sodium citrate was 0.04 mol / L, and the pH was adjusted to 4.5. Then, the amino-functionalized cattail fluff was immersed in the FeCl3 solution at a solid-liquid ratio of 1:15 g / mL, and transferred to a constant temperature oscillator for oscillation reaction for 2 hours. The oscillation reaction conditions were 25°C, 150 rpm, and then centrifuged at 4000 rpm for 10 minutes. After washing, it was placed in a vacuum drying oven at 60°C for drying to obtain iron ion loaded cattail fluff.

[0036] S2: Hydrothermal template synthesis of β-manganese dioxide

[0037] S2.1: Add MnSO4·H2O and (NH4)2S2O8 in a 1:1 molar ratio to a 0.1 mol / L aqueous glucose solution while stirring until Mn 2+ The concentration is 0.2 mol / L to obtain a manganese-glucose solution;

[0038] S2.2: The iron ion loaded cattail down and manganese-glucose solution were mixed uniformly at a solid-liquid ratio of 1:60 g / mL, then sealed in a polytetrafluoroethylene-lined stainless steel autoclave, the hydrothermal reaction temperature was set to 140°C, and the time was 12 hours. After the reaction was completed, the reaction solution was centrifuged at a speed of 6000 rpm for 10 minutes. The bottom precipitate was taken and added with 15 times the mass of anhydrous ethanol for centrifugation again. The precipitate was collected and dried at 80°C to obtain a manganese dioxide oxygen vacancy precursor template loaded with β.

[0039] S3: Vacuum impregnation and calcination treatment of the precursor template

[0040] S3.1: 6 parts by weight of europium nitrate hexahydrate powder and 3.5 parts by weight of cobalt tetramethoxyphenyl porphyrin were added to 30 parts by weight of anhydrous ethanol, and a mixed impregnation solution was obtained after stirring uniformly. 6 parts by weight of the manganese dioxide oxygen vacancy precursor template loaded with β was immersed in the mixed impregnation solution, then transferred to a vacuum impregnation tank for vacuum impregnation, and taken out and transferred to a forced air drying oven for drying at 75°C to obtain a rare earth complex coated oxygen vacancy precursor template;

[0041] S3.2: The rare earth complex coated oxygen vacancy precursor template was placed in a tubular vacuum furnace, heated to 480°C at a heating rate of 5°C / min under a vacuum condition of 0.1 Pa, and then kept for 1 hour. After natural cooling to room temperature, it was washed with deionized water for 2 times, and then dried at 60°C to obtain a manganese dioxide composite material.

[0042] Example 2

[0043] A manganese dioxide composite material for a battery and a preparation process thereof, as shown in Figure 1 , comprising the following steps:

[0044] S1: Preparation of iron ion loaded cattail down

[0045] S1.1: The cattail down was immersed in an ethanol solution with a concentration of 25%, and then subjected to ultrasonic treatment at 200W and 30kHz for 25 minutes. After being taken out, it was placed in a vacuum drying oven at 60°C for drying to obtain cleaned cattail down. 3-aminopropyl triethoxysilane was mixed with anhydrous ethanol at a volume ratio of 1:20, and acetic acid was used to adjust the pH to 5. Hydrolysis was carried out for 20 minutes to obtain a 3-aminopropyl triethoxysilane solution. The cleaned cattail down was immersed in the 3-aminopropyl triethoxysilane solution at a solid-liquid ratio of 1:15 g / mL, and then stirred uniformly. After being placed at 45°C for 1 hour, the solid residue was filtered, washed and dried to obtain amino-functionalized cattail down.

[0046] S1.2: FeCl3, sodium citrate and deionized water were mixed to prepare a Fe 3+FeCl3 solution with a concentration of 0.3 mol / L and a sodium citrate concentration of 0.05 mol / L, the pH is adjusted to 4.5, then the amino-functionalized cattail fluff is immersed in the FeCl3 solution at a solid-liquid ratio of 1:20 g / mL, and is transferred to a constant-temperature oscillator for oscillation reaction for 2 hours, the oscillation reaction conditions are 25℃ and 150 rpm, then centrifugation is performed at 4000 rpm for 10 minutes, and after washing, drying is performed in a 60℃ vacuum drying box, to obtain the iron ion-loaded cattail fluff.

[0047] S2: Hydrothermal template synthesis of β-manganese dioxide

[0048] S2.1: Under stirring, MnSO4·H2O and (NH4)2S2O8 are added to a glucose aqueous solution with a concentration of 0.1 mol / L at a molar ratio of 1:1.2, until the Mn 2+ A manganese-glucose solution with a concentration of 0.3 mol / L is obtained;

[0049] S2.2: The iron ion-loaded cattail fluff and the manganese-glucose solution are mixed uniformly at a solid-liquid ratio of 1:80 g / mL, then are sealed in a polytetrafluoroethylene-lined stainless steel autoclave, the hydrothermal reaction temperature is set to 140℃, and the time is 12 hours, after the reaction is completed, the reaction solution is centrifuged at a speed of 6000 rpm for 10 minutes, the bottom precipitate is taken and added with 15 times the mass of anhydrous ethanol for centrifugation again, the precipitate is collected and dried at 80℃, to obtain the oxygen vacancy precursor template loaded with β-manganese dioxide.

[0050] S3: Vacuum impregnation and calcination treatment of the precursor template

[0051] S3.1: 6.5 parts by weight of europium nitrate hexahydrate powder and 4 parts by weight of cobalt tetramethoxyphenyl porphyrin are added to 30 parts by weight of anhydrous ethanol, and after stirring uniformly, a mixed impregnation solution is obtained, 8 parts by weight of the oxygen vacancy precursor template loaded with β-manganese dioxide is immersed in the mixed impregnation solution, then is transferred to a vacuum impregnation tank for vacuum impregnation, is taken out and dried in a blast drying oven at 75℃, to obtain the oxygen vacancy precursor template coated with rare earth complexes;

[0052] S3.2: The oxygen vacancy precursor template coated with rare earth complexes is placed in a tubular vacuum furnace, heated to 480℃ at a heating rate of 5℃ / min under a vacuum condition of 0.1 Pa, and then kept for 1 hour, naturally cooled to room temperature, washed with deionized water for 2 times, and then dried at 60℃, to obtain the manganese dioxide composite material.

[0053] Example 3

[0054] A manganese dioxide composite material for a battery and a preparation process thereof, like Figure 1As shown, comprising the following steps:

[0055] S1: Preparation of iron ion loaded cattail down

[0056] S1.1: The cattail down was immersed in an ethanol solution with a concentration of 30%, then subjected to ultrasonic treatment for 30 minutes at 220W and 35kHz, and after being taken out, it was placed in a vacuum drying oven at 65°C for drying. The cleaned cattail down was obtained. 3-aminopropyltriethoxysilane was mixed with anhydrous ethanol at a volume ratio of 1:15, and the pH was adjusted to 5.5 with acetic acid. Hydrolysis was carried out for 25 minutes to obtain a 3-aminopropyltriethoxysilane solution. The cleaned cattail down was immersed in the 3-aminopropyltriethoxysilane solution at a solid-liquid ratio of 1:10 g / mL, and after being stirred uniformly, it was placed at 50°C for 2 hours. The solid residue was filtered, washed and dried to obtain amino-functionalized cattail down.

[0057] S1.2: FeCl3, sodium citrate and deionized water were mixed to prepare a Fe 3+ solution with a concentration of 0.2 mol / L and a sodium citrate concentration of 0.04 mol / L, and the pH was adjusted to 5. Then the amino-functionalized cattail down was immersed in the FeCl3 solution at a solid-liquid ratio of 1:15 g / mL, and was transferred to a constant temperature oscillator for oscillation reaction for 3 hours at 25°C and 200 rpm. Then it was centrifuged at 5000 rpm for 15 minutes, washed and placed in a vacuum drying oven at 65°C for drying to obtain iron ion loaded cattail down.

[0058] S2: Synthesis of β-manganese dioxide by hydrothermal templating method

[0059] S2.1: Under stirring, MnSO4·H2O and (NH4)2S2O8 were added to a glucose aqueous solution with a concentration of 0.2 mol / L at a molar ratio of 1:1 until the Mn 2+ concentration in the solution was 0.2 mol / L to obtain a manganese-glucose solution;

[0060] S2.2: The iron ion loaded cattail down and the manganese-glucose solution were mixed uniformly at a solid-liquid ratio of 1:60 g / mL, and then were sealed in a stainless steel autoclave lined with polytetrafluoroethylene. The hydrothermal reaction temperature was set to 145°C, and the time was 13 hours. After the reaction was completed, the reaction solution was centrifuged at a speed of 8000 rpm for 15 minutes. The bottom precipitate was added with 20 times the mass of anhydrous ethanol and was centrifuged again. The precipitate was collected and dried at 85°C to obtain an oxygen vacancy precursor template loaded with β-manganese dioxide.

[0061] S3: Vacuum impregnation and calcination treatment of the precursor template

[0062] S3.1: 6 parts by weight of europium nitrate hexahydrate powder and 3.5 parts by weight of tetramethoxyphenyl porphyrin cobalt were added to 30 parts by weight of anhydrous ethanol, and after stirring to be uniform, a mixed impregnation solution was obtained, 6 parts by weight of the oxygen vacancy precursor template loaded with β-manganese dioxide was immersed in the mixed impregnation solution, and then transferred to a vacuum impregnation tank for vacuum impregnation, taken out and transferred to a forced air drying oven for drying at 80℃, to obtain a rare earth complex coated oxygen vacancy precursor template;

[0063] S3.2: The rare earth complex coated oxygen vacancy precursor template was placed in a tubular vacuum furnace, heated to 500℃ at a heating rate of 10℃ / min under a vacuum condition of 0.5Pa, and then kept for 1.5 hours, naturally cooled to room temperature, washed with deionized water for 3 times, and then dried at 65℃ to obtain a manganese dioxide composite material.

[0064] Comparative Example 1: Different from Example 1, Comparative Example 1 did not load Fe on the cattail fluff 3+ The subsequent iron ion loaded cattail fluff was replaced by an equal mass of washed cattail fluff, and the remaining specific embodiments were the same as those of Example 1.

[0065] Comparative Example 2: Different from Example 1, Comparative Example 2 replaced the aqueous glucose solution of step S2.1 with an equal mass of deionized water to prepare a manganese pre-reaction solution, and the subsequent manganese-glucose solution was replaced by the manganese pre-reaction solution, and the remaining specific embodiments were the same as those of Example 1.

[0066] Comparative Example 3: Different from Example 1, Comparative Example 3 replaced the cattail fluff in step S1.1 with an equal mass of carbon cloth (W0S1011), and the remaining specific embodiments were the same as those of Example 1.

[0067] Comparative Example 4: Different from Example 1, Comparative Example 4 removed step S3.1, and replaced the rare earth complex coated oxygen vacancy precursor template with a β-manganese dioxide loaded oxygen vacancy precursor template, and the remaining specific embodiments were the same as those of Example 1.

[0068] The manganese dioxide composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were crushed to obtain samples, and then each sample, conductive carbon black and polyvinylidene fluoride were dispersed in N-methyl pyrrolidone solution at a mass ratio of 7:2:1, and stirred for four hours to obtain a uniformly dispersed slurry, which was uniformly coated on the surface of a titanium foil, dried and cut to obtain a positive electrode sheet, and finally the positive electrode sheet, zinc foil (negative electrode), separator (glass fiber) and 2MZnSO4+0.1MMnSO4 mixed solution (electrolyte) were assembled into a CR2032 type button cell.

[0069] Electrochemical performance test:

[0070] The constant current discharge specific capacity of the button cells assembled by the samples of Examples 1-3 and Comparative Examples 1-2 was tested by using a battery testing system, and the test rate was 0.1C, wherein 1C = 308 mAh / g during the battery testing, and the test was performed three times, and the test results are shown in Table 1.

[0071] Table 1: Discharge specific capacity of the button cells assembled by the samples at 0.1C

[0072]

[0073] As can be seen from the data of Examples 1-3 in Table 1, the button cells assembled by the samples prepared in Examples 1-3 all have high discharge specific capacity, and as can be seen from Comparative Example 1-2, the addition of Fe 3+ ions or glucose will cause a large decrease in the discharge specific capacity, which can prove that the Fe 3+ ions and the doping of glucose during the synthesis of β-manganese dioxide can effectively increase the discharge specific capacity of the manganese dioxide composite material as the positive electrode of the battery.

[0074] The rate performance and cycle performance of the button cells assembled by the samples of Examples 1-3 and Comparative Examples 3-4 were tested by using a battery testing system, the rate performance was tested by using a current density of 200 mA / g, 400 mA / g, 600 mA / g, 800 mA / g, 1000 mA / g, 2000 mA / g and 3000 mA / g, 5 charge-discharge cycles were performed at each rate, the average discharge capacity of the 5 charge-discharge cycles was taken, and the cycle performance was tested by the cycle number of the specific capacity greater than 80% at 1C rate, and the test results are shown in Table 2.

[0075] Table 2: Discharge specific capacity of the button cells assembled by the samples at different current densities

[0076]

[0077]

[0078] As can be seen from the data of Table 2, the button cells assembled by the samples prepared in Examples 1-3 all have excellent rate performance, and the cycle number of the specific capacity greater than 80% at 1C rate also reaches a high number, which indicates that they have good cycle stability, while the button cells assembled by the samples prepared in Comparative Examples 3-4 have decreased rate performance and cycle stability, which can prove that the use of cattail fluff as a template molecule and the doping of tetramethoxyphenyl porphyrin cobalt and europium nitrate during the calcination of manganese dioxide can improve the conductivity and stability of the manganese dioxide composite material, and enhance the rate performance and cycle stability.

[0079] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A process for the preparation of a manganese dioxide composite material for a battery, characterized in that, Comprising the following steps: S1: preparation of iron ion loaded cattail fluff After washing the cattail fluff, it is immersed in a 3-aminopropyl triethoxysilane solution for modification to obtain amino-functionalized cattail fluff. The amino-functionalized cattail fluff is immersed in a FeCl3 solution prepared by mixing FeCl3, sodium citrate and deionized water, and after oscillation reaction, centrifugation, washing and drying, iron ion loaded cattail fluff is obtained. S2: synthesis of beta-manganese dioxide by hydrothermal templating method MnSO4-H2O and (NH4)2S2O8 were added into the glucose aqueous solution under stirring until the concentration of Mn 2+ The concentration of MnSO4-H2O and (NH4)2S2O8 was 0.2-0.3 mol / L, and the manganese-glucose solution was obtained. Iron ions were added and mixed uniformly with the cattail down, and then transferred to an autoclave for hydrothermal reaction. After centrifugal cleaning and drying, the oxygen vacancy precursor template loaded with β-manganese dioxide was obtained. S3: vacuum impregnation and calcination treatment of precursor template The cobalt tetramethoxyphenyl porphyrin and europium nitrate hexahydrate are uniformly mixed in anhydrous ethanol, then the beta-manganese dioxide loaded oxygen vacancy precursor template is immersed in the solution and vacuum impregnated, taken out and dried, then placed in a tube furnace for vacuum calcination, cooled to room temperature, washed and dried to obtain the manganese dioxide composite material.

2. The process for the preparation of a manganese dioxide composite material for batteries according to claim 1, characterized in that, Step S1: preparation of iron ion loaded cattail fluff, comprising the following steps: S1.1: immerse the cattail fluff in an ethanol solution with a concentration of 25-30%, then perform ultrasonic treatment at 200-220W and 30-35kHz for 25-30 minutes, take out and dry in a vacuum drying oven at 60-65°C to obtain washed cattail fluff. Mix 3-aminopropyl triethoxysilane with anhydrous ethanol at a volume ratio of 1:(15-20), adjust the pH to 5-5.5 with acetic acid, and hydrolyze for 20-25 minutes to obtain a 3-aminopropyl triethoxysilane solution. Immerse the washed cattail fluff in the 3-aminopropyl triethoxysilane solution at a solid-liquid ratio of 1:(10-15) g / mL, stir uniformly, and then stand at 45-50°C for 1-2 hours. Filter the solid residue, wash and dry to obtain amino-functionalized cattail fluff. S1.2: FeCl3, sodium citrate and deionized water are mixed to prepare Fe 3+ FeCl3 solution with a concentration of 0.2-0.3 mol / L and a sodium citrate concentration of 0.04-0.05 mol / L, adjust the pH to 4.5-5, then immerse the amino-functionalized cattail fluff in the FeCl3 solution at a solid-liquid ratio of 1:(15-20) g / mL, transfer to a constant temperature oscillator for oscillation reaction for 2-3 hours, then centrifuge at 4000-5000 rpm for 10-15 minutes, wash and dry in a vacuum drying oven at 60-65°C to obtain iron ion-loaded cattail fluff.

3. A process for the preparation of a manganese dioxide composite material for a battery as claimed in claim 2, wherein, Step S2: synthesis of beta-manganese dioxide by hydrothermal templating method, comprising the following steps: S2.1 : MnS04-H20 and (NH4)2S208 are added to a glucose aqueous solution with a concentration of 0.1-0.2 mol / L in a molar ratio of 1 :(1-1.2) under stirring until the concentration of Mn 2+ concentration of 0.2- 0.3 mol / L, obtaining a manganese-glucose solution; S2.2: uniformly mix the iron ion loaded cattail fluff and the manganese-glucose solution at a solid-liquid ratio of 1:(60-80) g / mL, then seal in a polytetrafluoroethylene lined stainless steel autoclave, set the hydrothermal reaction temperature to 140-145°C, and the time to 12-13 hours. After the reaction is completed, centrifuge the reaction solution, add 15-20 times the mass of anhydrous ethanol to the bottom sediment, centrifuge again, collect the sediment, and dry at 80-85°C to obtain the beta-manganese dioxide loaded oxygen vacancy precursor template.

4. The process for the preparation of a manganese dioxide composite material for batteries according to claim 3, characterized in that, Step S3: vacuum impregnation and calcination treatment of precursor template, comprising the following steps: S3.1: add 6-6.5 parts by weight of europium nitrate hexahydrate powder and 3.5-4 parts by weight of cobalt tetramethoxyphenyl porphyrin to 30-40 parts by weight of anhydrous ethanol, stir uniformly to obtain a mixed impregnation solution, immerse 6-8 parts by weight of the beta-manganese dioxide loaded oxygen vacancy precursor template in the mixed impregnation solution, then transfer to a vacuum impregnation tank for vacuum impregnation, take out and transfer to a forced air drying oven for drying at 75-80°C to obtain a rare earth complex coated oxygen vacancy precursor template. S3.2: The rare earth complex coated oxygen vacancy precursor template is placed in a tubular vacuum furnace, heated to 480-500°C at a heating rate of 5-10°C / min under vacuum conditions of 0.1-0.5 Pa, and then kept for 1-1.5 hours, naturally cooled to room temperature, washed with deionized water for 2-3 times, and then dried at 60-65°C to obtain the manganese dioxide composite material.

5. The process for the preparation of a manganese dioxide composite material for batteries according to claim 2, characterized in that, The oscillation reaction in step S1.2 is at 25°C, 150-200 rpm.

6. The process for the preparation of a manganese dioxide composite material for batteries according to claim 3, characterized in that, The centrifugal speed in the centrifugation in step S2.2 is 6000-8000 rpm, and the time is 10-15 minutes.

7. The process for the preparation of a manganese dioxide composite material for batteries according to claim 4, characterized in that, The vacuum degree in the vacuum impregnation process in step S3.1 is 10-20 Pa, and the time is 30-35 minutes.

8. A manganese dioxide composite material for a battery, characterized by, It is prepared by the preparation process of the manganese dioxide composite material for a battery according to any one of claims 1-7.

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