Alpha-manganese dioxide composite electrode material and preparation method and application thereof

Abstract

The application discloses a kind of alpha-manganese dioxide composite electrode materials and preparation method and application, belong to electrode technical field, the application first potassium persulfate is used as oxidant, manganese sulfate monohydrate is used as manganese source, it is oxidized into high-valence manganese, then the morphology of alpha-MnO2 precursor is regulated using ionic liquid, form the alpha-MnO2 of specific structure and size, then incorporate alkaline substance, to obtain the alkali manganese compound as main active ingredient, effectively improve electrochemical performance, use polyamide acid as film-forming matrix, form the skeleton structure of nanofiber membrane in electrospinning process, regulate the performance of nanofiber membrane, finally heat treatment and carbonization, effectively improve the conductivity and stability of nanofiber membrane, the alpha-manganese dioxide composite electrode material prepared has excellent self-supporting, high specific surface area and nano composite structure.Can significantly improve the specific capacitance and energy density of electrode material, and give it excellent long cycle life.

Description

Technical Field

[0001] This invention relates to the field of electrode technology, specifically to an α-manganese dioxide composite electrode material, its preparation method, and its application. Background Technology

[0002] Hybrid supercapacitors, as a novel energy storage device, combine the high energy density of batteries with the high power density of supercapacitors, attracting significant attention in the energy storage field. Their principle combines the Faraday reaction of battery-type electrodes with the double-layer capacitance effect of capacitor-type electrodes. During charging and discharging, the former stores and releases energy through redox reactions, while the latter utilizes rapid ion adsorption and desorption to achieve fast charging and discharging.

[0003] Electrode materials are the core of hybrid supercapacitors. An ideal electrode needs high specific surface area, reasonable pore size distribution, good conductivity, excellent electrochemical stability, and a suitable potential window. However, existing materials have shortcomings, such as poor conductivity, slow ion diffusion, and low power density of metal oxides. Furthermore, the fabrication processes for some high-performance electrodes are complex and costly, making industrial-scale mass production difficult.

[0004] Therefore, developing a novel electrode material that can overcome the shortcomings of existing technologies, especially one with significant advantages in improving specific capacitance, conductivity, stability, and feasibility of industrial fabrication, is crucial for the further development of hybrid supercapacitor technology. Simultaneously, this material must possess high specific capacitance, high energy density, long cycle life, and economic viability to meet the diverse needs of future energy storage technologies.

[0005] Therefore, this application is submitted. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the existing technology and provide an α-manganese dioxide composite electrode material, its preparation method and application, which has high specific capacitance, high energy density and long cycle life.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0009] (1) Dissolve potassium persulfate and manganese sulfate monohydrate in water, add ionic liquid, stir evenly, dry and calcine to obtain nano α-MnO2 precursor;

[0010] (2) Dissolve nano-α-MnO2 precursor and alkaline substance in water and react to obtain alkali manganese compound;

[0011] (3) Mix the alkali manganese compound and the polyamic acid solution evenly to obtain a mixture, and dilute it with a solvent until the polyamic acid concentration in the mixture is 10~17% to obtain a spinning solution;

[0012] (4) Put 2~7mL of spinning solution into a syringe, connect the stainless steel flat-mouth needle to the positive electrode, connect the receiving plate to the negative electrode, and perform electrospinning to obtain a nanofiber membrane.

[0013] (5) Heat-treat and carbonize the nanofiber membrane to obtain α-manganese dioxide composite electrode material.

[0014] This invention first uses potassium persulfate as an oxidant and manganese sulfate monohydrate as a manganese source to oxidize it to high-valence manganese. Then, ionic liquids are used to regulate the morphology of the α-MnO2 precursor, forming α-MnO2 with a specific structure and size. Next, an alkaline substance is incorporated, with the resulting alkali manganese compound serving as the main active ingredient, effectively improving electrochemical performance. Polyamic acid is used as the film-forming matrix, forming the framework structure of the nanofiber membrane during electrospinning, thus regulating the performance of the nanofiber membrane. Finally, heat treatment and carbonization are performed to effectively improve the conductivity and stability of the nanofiber membrane. The resulting α-manganese dioxide composite electrode material overcomes the limitations of traditional electrodes that rely on binders and metal current collectors, exhibiting excellent self-support, high specific surface area, and a nanocomposite structure. Compared to unoptimized precursors or spinning processes, the method of this invention can significantly improve the specific capacitance and energy density of the electrode material and endow it with excellent long cycle life, mainly due to the tight composite of the active material and the highly conductive carbon fiber network, as well as the optimized ion / electron transport pathway.

[0015] As a preferred embodiment of the present invention, the ionic liquid includes at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide (CAS No.: 85100-77-2), and 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0016] In a preferred embodiment of the present invention, the ratio of potassium persulfate, manganese sulfate monohydrate, water, and ionic liquid is (15~20) mmol: (15~20) mmol: (50~100) mL: (0.1~0.5) mL;

[0017] The calcination temperature is 550~700℃, and the calcination time is 1~2h.

[0018] As a preferred embodiment of the present invention, the ratio of the nano α-MnO2 precursor, the alkaline substance, and the water is 212 mg: (110~380) mg: (40~50) mL;

[0019] The alkaline substance includes at least one of potassium hydroxide, lithium hydroxide, calcium hydroxide, nickel hydroxide, and cobalt hydroxide;

[0020] The reaction temperature is 180~220℃, and the reaction time is 10~20h.

[0021] In a preferred embodiment of the present invention, the ratio of the alkali manganese compound to the polyamic acid solution is (0.01~0.048) g : (3.5~8.5) mL;

[0022] The solvent includes at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0023] The solid content of the polyamic acid solution is 18-25%.

[0024] In a preferred embodiment of the present invention, the electrospinning voltage is 18~22kV, the temperature is 50~55℃, the spinning speed is 0.02~0.18 mL / min, and the spacing is 9~18cm.

[0025] As a preferred embodiment of the present invention, the heat treatment is first held at 90~110℃ for 0.5~2h, and then held at 170~190℃ for 2~6h.

[0026] In a preferred embodiment of the present invention, the carbonization temperature is 800~1000℃ and the carbonization time is 1~2h.

[0027] The present invention also provides an α-manganese dioxide composite electrode material, which is prepared by the preparation method described above.

[0028] The present invention also provides an application of α-manganese dioxide composite electrode material in the preparation of super hybrid capacitors, wherein the α-manganese dioxide composite electrode material serves as an electrode of the super hybrid capacitor.

[0029] The beneficial effects of the present invention are as follows: (1) The present invention first uses potassium persulfate as an oxidant and manganese sulfate monohydrate as a manganese source to oxidize it into high-valence manganese. Then, ionic liquid is used to regulate the morphology of α-MnO2 precursor to form α-MnO2 with specific structure and size. Then, alkaline substances are added to obtain alkaline manganese compounds as the main active ingredients, which effectively improves the electrochemical performance. Polyamic acid is used as the film-forming matrix to form the skeleton structure of nanofiber membrane during electrospinning, thereby regulating the performance of nanofiber membrane. Finally, heat treatment and carbonization are carried out to effectively improve the conductivity and stability of nanofiber membrane. The α-manganese dioxide composite electrode material prepared breaks through the limitations of traditional electrodes that rely on binders and metal current collectors. It has excellent self-support, high specific surface area and nanocomposite structure. Compared with unoptimized precursors or spinning processes, the method of the present invention can significantly improve the specific capacitance and energy density of electrode materials and endow them with excellent long cycle life. This is mainly due to the close composite of active material and highly conductive carbon fiber network and the optimized ion / electron transport path.

[0030] (2) The process steps of the method described in this invention are clear, the raw materials are readily available, and it is suitable for constructing high-performance manganese-based oxide / carbon composite electrode systems. The preparation cost is relatively controllable and it has good prospects for industrial application. Attached Figure Description

[0031] Figure 1 The image shows a scanning electron microscope (SEM) image of the α-manganese dioxide composite electrode material prepared in Example 1.

[0032] Figure 2 The image shows a scanning electron microscope (EDS) image of the α-manganese dioxide composite electrode material prepared in Example 1. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0035] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0036] In this application, there are no particular restrictions on the specific dispersion and mixing methods.

[0037] Unless otherwise specified, all components, raw materials, or instruments used in the embodiments and comparative examples of this invention are commercially available, and the same type of components and raw materials are used in each parallel experiment.

[0038] The following embodiments are provided to facilitate understanding of the invention. These embodiments are not intended to limit the scope of the claims.

[0039] Example 1

[0040] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0041] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.5 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0042] (2) Dissolve 212 mg of nano α-MnO2 precursor and 380 mg of potassium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0043] (3) Mix 0.01g of alkali manganese compound and 5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylformamide until the polyamic acid concentration in the mixture is 17% to obtain a spinning solution.

[0044] (4) Put 3.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 15 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.025 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0045] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 1000°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0046] The scanning electron microscope image of the prepared α-manganese dioxide composite electrode material is shown below. Figure 1 As shown, the material exhibits a relatively dense porous network structure with a relatively uniform pore distribution. The microstructure of the material mainly presents an interconnected network or dendritic structure, which facilitates the transport of matter and provides an attachment space for other substances. Figure 2 The elemental distribution mapping of the product is shown. Figure 2 It can be seen that elements such as K, Mn, C, N, and O are all present in the sample. Except for C, which has a wider distribution range, K, Mn, N, and O are all dispersed and uniformly distributed in a point-like manner, without obvious local enrichment, which contributes to the uniformity of material properties.

[0047] Example 2

[0048] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0049] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.1 mL of 1-butyl-3-methylimidazolium bromide, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure reactor lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 8 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter it. After drying overnight at 110°C, calcine the prepared sample in air at 600°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0050] (2) Dissolve 212 mg of nano α-MnO2 precursor and 110 mg of lithium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0051] (3) Mix 0.035g of alkali manganese compound and 3.5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylacetamide until the polyamic acid concentration in the mixture is 10% to obtain a spinning solution.

[0052] (4) Put 2 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 9 cm, the voltage is 20 kV high voltage, the heating parameters are set to the temperature of 52°C, the speed of the pusher is 0.04 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0053] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 800°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0054] The morphology of the product obtained in this embodiment is similar to that in Example 1. It exhibits a relatively dense porous network structure with relatively uniform pore distribution. The microstructure mainly shows an interconnected network or dendritic structure, which helps the transport of substances and provides an attachment space for other substances. It is rich in Li, Mn, C, N and O elements.

[0055] Example 3

[0056] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0057] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.3 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 16 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 650°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0058] (2) Dissolve 212 mg of nano α-MnO2 precursor and 230 mg of calcium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0059] (3) Mix 0.034g of alkali manganese compound and 8.5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with dimethyl sulfoxide until the polyamic acid concentration in the mixture is 15% to obtain a spinning solution.

[0060] (4) Put 7 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 12 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.18 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0061] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 900°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0062] The morphology of the product obtained in this embodiment is similar to that in Example 1. It exhibits a relatively dense porous network structure with relatively uniform pore distribution. The microstructure mainly shows an interconnected network or dendritic structure, which helps the transport of substances and provides an attachment space for other substances. It is rich in Ca, Mn, C, N and O elements.

[0063] Example 4

[0064] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0065] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.2 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 12 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 700°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0066] (2) Dissolve 212 mg of nano α-MnO2 precursor and 280 mg of nickel hydroxide in 45 mL of water, transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it, and react at 200 °C for 12 h to obtain an alkali manganese compound.

[0067] (3) Mix 0.027g of alkali manganese compound and 4.5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N-methylpyrrolidone until the polyamic acid concentration in the mixture is 12% to obtain a spinning solution.

[0068] (4) Put 3 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 10 cm, the voltage is 20 kV high voltage, the heating parameters are set to the temperature of 52°C, the speed of the pusher is 0.12 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0069] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 800°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0070] The morphology of the product obtained in this embodiment is similar to that of Example 1. It exhibits a relatively dense porous network structure with relatively uniform pore distribution. The microstructure mainly shows an interconnected network or dendritic structure, which helps the transport of substances and provides an attachment space for other substances. It is rich in Ni, Mn, C, N and O elements.

[0071] Example 5

[0072] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0073] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.4 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 20 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0074] (2) Dissolve 212 mg of nano α-MnO2 precursor and 300 mg of sodium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0075] (3) Mix 0.013g of alkali manganese compound and 6.5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N-methylpyrrolidone until the polyamic acid concentration in the mixture is 16% to obtain a spinning solution.

[0076] (4) Put 5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 14 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.08 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0077] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 900°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0078] The morphology of the product obtained in this embodiment is similar to that in Example 1. It exhibits a relatively dense porous network structure with relatively uniform pore distribution. The microstructure mainly shows an interconnected network or dendritic structure, which helps the transport of substances and provides an attachment space for other substances. It is rich in Na, Mn, C, N and O elements.

[0079] Example 6

[0080] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0081] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.1 mL of 1-ethyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0082] (2) Dissolve 212 mg of nano α-MnO2 precursor and 350 mg of cobalt hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0083] (3) Mix 0.048g of alkali manganese compound and 6mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylformamide until the polyamic acid concentration in the mixture is 13% to obtain a spinning solution.

[0084] (4) Put 4.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 11 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.1 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0085] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 1000°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0086] The morphology of the product obtained in this embodiment is similar to that in Example 1. It exhibits a relatively dense porous network structure with relatively uniform pore distribution. The microstructure mainly shows an interconnected network or dendritic structure, which helps the transport of substances and provides an attachment space for other substances. It is rich in Co, Mn, C, N and O elements.

[0087] Comparative Example 1

[0088] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0089] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water and stir at 100 rpm for 30 min. Transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene (PTFE) and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the PTFE liner several times with deionized water and then filter it. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-β-MnO2 precursor.

[0090] (2) Dissolve 212 mg of nano α-MnO2 precursor and 380 mg of potassium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0091] (3) Mix 0.01g of alkali manganese compound and 5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylformamide until the polyamic acid concentration in the mixture is 17% to obtain a spinning solution.

[0092] (4) Put 3.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 15 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.025 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0093] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 1000°C for 1.5 hours to obtain β-manganese dioxide composite electrode material.

[0094] Comparative Example 2

[0095] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0096] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.5 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0097] (2) Dissolve 212 mg of nano α-MnO2 precursor and 380 mg of potassium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0098] (3) Mix 0.01g of alkali manganese compound and 5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture, which is then used as a spinning solution;

[0099] (4) Put 3.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 15 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.025 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0100] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 1000°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0101] Comparative Example 3

[0102] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0103] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.5 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0104] (2) Dissolve 212 mg of nano α-MnO2 precursor and 380 mg of potassium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0105] (3) Mix 0.01g of alkali manganese compound and 5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylformamide until the polyamic acid concentration in the mixture is 5% to obtain a spinning solution.

[0106] (4) Put 3.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 15 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.025 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0107] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 1000°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0108] Comparative Example 4

[0109] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0110] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.5 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0111] (2) Dissolve 212 mg of nano α-MnO2 precursor and 380 mg of potassium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0112] (3) Mix 0.01g of alkali manganese compound and 5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylformamide until the polyamic acid concentration in the mixture is 17% to obtain a spinning solution.

[0113] (4) Put 3.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 15 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.025 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0114] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 600°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0115] Comparative Example 5

[0116] A method for preparing an α-manganese dioxide composite electrode material includes the following steps:

[0117] (1) Dissolve 17 mmol potassium persulfate and 17 mmol manganese sulfate monohydrate in 75 mL of water, add 0.5 mL of 1-butyl-3-methylimidazolium tetrafluoroborate, stir at 100 rpm for 30 min, transfer the mixed solution to a high-pressure autoclave lined with polytetrafluoroethylene, and keep it in an oven at 160°C for 24 h. After cooling to room temperature, wash the precipitate in the polytetrafluoroethylene liner several times with deionized water and then filter. After drying overnight at 110°C, calcine the prepared sample in air at 550°C for 1.5 h in a high-temperature furnace to obtain nano-α-MnO2 precursor;

[0118] (2) Dissolve 212 mg of nano α-MnO2 precursor and 380 mg of potassium hydroxide in 45 mL of water. Transfer the mixture to a polytetrafluoroethylene liner, place it in a stainless steel reactor and seal it. React at 200 °C for 12 h to obtain an alkali manganese compound.

[0119] (3) Mix 0.01g of alkali manganese compound and 5mL of polyamic acid solution with a solid content of 20% evenly to obtain a mixture. Dilute with N,N-dimethylformamide until the polyamic acid concentration in the mixture is 17% to obtain a spinning solution.

[0120] (4) Put 3.5 mL of spinning solution into a 10 mL syringe, connect the stainless steel flat needle to the positive electrode, connect the receiving plate to the negative electrode, the distance between the two plates is 15 cm, the voltage is 20 kV high voltage, the heating parameters are set to 52°C, the pusher speed is 0.025 mL / min, turn on the instrument to perform electrospinning, and obtain nanofiber membrane.

[0121] (5) The nanofiber membrane was placed in a forced-air drying oven and heat-treated at 100°C for 1 hour, and then heat-treated at 180°C for 4 hours. The cooled nanofiber membrane was placed in a high-temperature tube furnace filled with nitrogen and carbonized at 1200°C for 1.5 hours to obtain α-manganese dioxide composite electrode material.

[0122] Test case

[0123] The α-manganese dioxide composite electrode material was cut into circular pieces with a diameter of 12 mm and a thickness of 60 μm as the working electrode. An activated carbon electrode of the same size was selected as the counter electrode, glass fiber paper as the separator, and a mixed solution of 6.0 mol / L KOH and 0.2 mol / L zinc acetate as the electrolyte. The button-type device was assembled in a glove box according to the sequence: "bottom cover → counter electrode → electrolyte-immersed separator → working electrode → gasket → spring contact → top cover," and tested after standing for 24 hours. The specific capacity, energy density, and capacity retention after 1000 cycles are shown in Table 1.

[0124] Table 1

[0125]

[0126] As shown in Table 1, this invention first uses potassium persulfate as an oxidant and manganese sulfate monohydrate as a manganese source to oxidize it into high-valence manganese. Then, ionic liquids are used to regulate the morphology of the α-MnO2 precursor, forming α-MnO2 with a specific structure and size. Alkaline substances are then incorporated, with the resulting alkali manganese compound serving as the main active ingredient, effectively improving electrochemical performance. Polyamic acid is used as the film-forming matrix, forming the framework structure of the nanofiber membrane during electrospinning, thus regulating the performance of the nanofiber membrane. Finally, heat treatment and carbonization are performed to effectively improve the conductivity and stability of the nanofiber membrane. The prepared α-manganese dioxide composite electrode material overcomes the limitations of traditional electrodes that rely on binders and metal current collectors, exhibiting excellent self-support, high specific surface area, and a nanocomposite structure. Compared to unoptimized precursors or spinning processes, the method of this invention can significantly improve the specific capacitance and energy density of the electrode material and endow it with excellent long cycle life, mainly due to the tight composite of the active material and the highly conductive carbon fiber network, as well as the optimized ion / electron transport pathway.

[0127] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an α-manganese dioxide composite electrode material, characterized by, The method comprises the following steps: (1) dissolving potassium persulfate and manganese sulfate monohydrate in water, adding an ionic liquid, stirring uniformly, solvent thermal reaction, drying, calcination, and obtaining a nano α-MnO2 precursor; (2) dissolving the nano α-MnO2 precursor and an alkaline substance in water, and hydrothermal reaction to obtain an alkaline manganese compound; (3) mixing the alkaline manganese compound and a polyamic acid solution uniformly to obtain a mixed solution, and diluting the mixed solution with a solvent to obtain a spinning solution with a polyamic acid concentration of 10-17%; (4) placing 2-7 mL of the spinning solution into a needle tube, connecting a stainless steel flat needle head to a positive electrode, and connecting a receiving plate to a negative electrode to perform electrostatic spinning, and obtaining a nanofiber membrane; (5) heat treating the nanofiber membrane, carbonizing, and obtaining an α-manganese dioxide composite electrode material.

2. The preparation method of the α-manganese dioxide composite electrode material according to claim 1, characterized in that, The ionic liquid comprises at least one of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide, and 1-ethyl-3-methylimidazolium tetrafluoroborate.

3. The method of claim 1, wherein the α-manganese dioxide composite electrode material is prepared by the steps of: (a) mixing manganese dioxide, a binder, and a conductive material to form a mixture; (b) coating the mixture on a current collector; and (c) drying the mixture coated on the current collector. The potassium persulfate, manganese sulfate monohydrate, water, and ionic liquid in the step (1) are used in a ratio of (15-20) mmol:(15-20) mmol:(50-100) mL:(0.1-0.5) mL. The calcination temperature is 550-700 DEG C, and the calcination time is 1-2 h.

4. The method of claim 1, wherein the α-manganese dioxide composite electrode material is prepared by the steps of: (a) mixing manganese dioxide, a binder, and a conductive material to form a mixture; (b) coating the mixture on a current collector; and (c) drying the mixture coated on the current collector. The nano α-MnO2 precursor, alkaline substance, and water in the step (2) are used in a ratio of 212 mg:(110-380) mg:(40-50) mL. The alkaline substance comprises at least one of potassium hydroxide, lithium hydroxide, calcium hydroxide, nickel hydroxide, and cobalt hydroxide. The reaction temperature is 180-220 DEG C, and the reaction time is 10-20 h.

5. The method of claim 1, wherein the α-manganese dioxide composite electrode material is prepared by the steps of: (a) mixing manganese dioxide, carbon black, and a binder to form a mixture; (b) coating the mixture on a current collector; and (c) drying the coated current collector. The alkaline manganese compound and polyamic acid solution are used in a ratio of (0.01-0.048) g:(3.5-8.5) mL. The solvent comprises at least one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methyl pyrrolidone. The solid content of the polyamic acid solution is 18-25%.

6. The method of claim 1, wherein the α-manganese dioxide composite electrode material is prepared by the steps of: The electrostatic spinning voltage is 18-22 kV, the temperature is 50-55 DEG C, the spinning speed is 0.02-0.18 mL / min, and the spacing is 9-18 cm.

7. The method of claim 1, wherein the α-manganese dioxide composite electrode material is prepared by the steps of: (a) mixing manganese dioxide, carbon black, and a binder to form a mixture; (b) coating the mixture on a current collector; and (c) drying the coated current collector. The heat treatment is first kept at 90-110 DEG C for 0.5-2 h, and then kept at 170-190 DEG C for 2-6 h.

8. The method of claim 1, wherein the α-manganese dioxide composite electrode material is prepared by the steps of: (a) mixing manganese dioxide, carbon black, and a binder to form a mixture; (b) coating the mixture on a current collector; and (c) drying the coated current collector. The carbonization temperature is 800-1000 DEG C, and the carbonization time is 1-2 h.

9. An a-manganese dioxide composite electrode material, characterized by, The α-manganese dioxide composite electrode material is prepared by the preparation method in any one of claims 1-8.

10. Use of the alpha-manganese dioxide composite electrode material according to claim 9 for the production of a super hybrid capacitor, characterized in that The α-manganese dioxide composite electrode material is used as an electrode of a super hybrid capacitor.

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