Manganese oxide / indium tin oxide composite material and preparation method and application thereof

Abstract

This invention discloses a manganese oxide / indium tin oxide composite material, its preparation method, and its application. The preparation method includes: 1) subjecting carbon fibers to high-temperature oxidation treatment; 2) placing the oxidized carbon fibers in a potassium permanganate solution and performing a hydrothermal reaction at high temperature to grow manganese dioxide nanosheets to obtain an electrode sheet; 3) placing the electrode sheet in a mixed solution of ethanol and ethylene glycol containing manganese acetate and performing a hydrothermal reaction to grow manganese dioxide / manganese tetroxide nanospheres; 4) subjecting the manganese dioxide / manganese tetroxide nanosphere electrode obtained in step 3) to charge-discharge cycles in an electrolyte containing indium tin oxide, and after the cycles are completed, repeatedly washing with deionized water and drying to obtain the manganese dioxide / indium tin oxide electrode material. The manganese oxide / indium tin oxide composite material prepared by this invention has nanoparticles on its surface and exhibits a larger specific capacitance compared to other manganese oxide nanomaterials or composite materials.

Description

Technical Field

[0001] This invention belongs to the field of supercapacitor technology, specifically relating to a manganese oxide / indium tin oxide composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of science and technology, traditional fossil fuels can no longer meet human energy demands. The development of advanced energy conversion and storage devices, such as lithium-ion batteries, fuel cells, and supercapacitors, is now imperative. Over the past few decades, supercapacitors have garnered widespread attention due to their long lifespan, fast charging and discharging, and high power density. Supercapacitors are classified into electric double-layer capacitors (EDLCs) and pseudocapacitors (PDCs). Electrode materials are crucial in determining supercapacitor performance. Metal oxides are currently the most commonly used supercapacitor electrode materials besides carbon materials. Among the many types of transition metal oxides, MnO2 stands out as a promising electrode material due to its very high theoretical capacitance and lithium and sodium storage properties. However, pure MnO2 electrodes often suffer from rapid capacitance decay and poor cycle performance when used as supercapacitor electrode materials. Therefore, preparing composite materials of MnO2 can leverage the synergistic effect between different components to compensate for the shortcomings of MnO2, thereby improving the overall performance of supercapacitors. The combination of manganese dioxide and carbon materials is the most common two-dimensional composite; for example, the combination of MnO2 and CNTs can achieve good conductivity, mechanical strength, and chemical stability. In-situ growth of MnO2 petals on the graphene surface can achieve a large contact area, thereby shortening the ion diffusion path. Besides being combined with carbon materials, manganese dioxide is also frequently combined with pseudocapacitive materials, such as polypyrrole, polyaniline, NiO, Co3O4, and Fe2O3. Composite metal oxides, as electrode materials for supercapacitors, can achieve a larger specific capacitance than the electrode layer and exhibit good cycle performance. However, transition metal oxides generally have poor conductivity, which will partially hinder the electron and charge transport processes in the fabricated electrode material, thus negatively impacting the overall performance of the electrode material. Summary of the Invention

[0003] To address the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing a manganese oxide / indium tin oxide composite material. First, oxidized carbon fibers are reacted with potassium permanganate to grow manganese dioxide nanosheets. Then, manganese dioxide / manganese tetroxide nanospheres are grown via a hydrothermal reaction at high temperature in a mixed solution of manganese acetate in ethanol and ethylene glycol. Finally, the material is circulated several times in an electrolyte containing indium tin oxide to obtain a high-performance manganese dioxide / indium tin oxide composite electrode material.

[0004] Another object of the present invention is to provide a manganese oxide / indium tin oxide composite material prepared by the above preparation method.

[0005] Another object of the present invention is to provide the application of the above-mentioned manganese oxide / indium tin oxide composite material in supercapacitors.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a manganese oxide / indium tin oxide composite material, comprising the following steps:

[0008] (1) High-temperature oxidation of carbon fiber

[0009] After cleaning and drying, carbon fibers are oxidized in air to obtain oxidized carbon fibers.

[0010] (2) Hydrothermal growth of manganese oxides from potassium permanganate

[0011] The carbon dioxide from step (1) was placed in a potassium permanganate solution and manganese dioxide was grown by hydrothermal reaction. After washing and drying, the electrode sheet was obtained.

[0012] (3) Growth of manganese tetroxide

[0013] The electrode sheet from step (2) was placed in a manganese acetate solution to grow manganese tetroxide via a hydrothermal reaction. After cleaning and drying, manganese oxide electrode material was obtained.

[0014] (4) Preparation of manganese dioxide / indium tin oxide electrode material

[0015] The manganese oxide electrode material from step (3) is subjected to charge-discharge cycle treatment in an electrolyte containing indium tin oxide, then cleaned and dried to obtain a high-performance manganese dioxide / indium tin oxide electrode material.

[0016] Preferably, the carbon fiber described in step (1) is ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried.

[0017] Preferably, the oxidation treatment temperature in step (1) is 200-700℃, more preferably 300-700℃; the oxidation treatment time is 1-6 h, more preferably 2-6 h.

[0018] Preferably, the concentration of the potassium permanganate solution in step (2) is 1 to 10 mg / mL, more preferably 1 to 9 mg / mL.

[0019] Preferably, the temperature of the hydrothermal reaction in step (2) is 140-190°C, and the time of the hydrothermal reaction is 2-8 h, more preferably 4-8 h.

[0020] Preferably, the concentration of manganese acetate in the manganese acetate solution in step (3) is 1 to 10 mg / mL, more preferably 2 to 8 mg / mL.

[0021] Preferably, the manganese acetate solution in step (3) is prepared from manganese acetate, ethanol, ethylene glycol and water.

[0022] More preferably, the volume ratio of ethanol, ethylene glycol and water is (1-4):(2-8):1, and even more preferably (1-4):(3-8):1.

[0023] Preferably, the temperature of the hydrothermal reaction in step (3) is 120-200°C, more preferably 120-190°C; and the time of the hydrothermal reaction is 4-8 h, more preferably 5-8 h.

[0024] Preferably, in the electrolyte containing indium tin oxide in step (4), the concentration of indium tin oxide is 0.01 to 1 mg / mL, more preferably 0.02 to 0.9 mg / mL.

[0025] The electrolyte containing indium tin oxide in step (4) is a sodium sulfate electrolyte containing indium tin oxide, wherein the concentration of sodium sulfate is 0.1 to 10 mol / L.

[0026] Preferably, the number of charge-discharge cycles in step (4) is 4 to 5000 times, more preferably 20 to 3000 times.

[0027] Preferably, the window voltage of the charge-discharge cycle in step (4) is 0 to 1.2 V.

[0028] Preferably, the cleaning described in steps (2) to (4) refers to cleaning with deionized water.

[0029] The carbon fibers in the manganese oxide / indium tin oxide composite material (i.e., manganese oxide nanostructure electrode material) are loaded with two different transition metal oxides, and the process adopted is indium tin oxide composite doping during electrochemical cyclic phase transition.

[0030] Secondly, the present invention provides a manganese oxide / indium tin oxide composite material prepared by the above preparation method.

[0031] Thirdly, the present invention provides the application of the aforementioned manganese oxide / indium tin oxide composite material in supercapacitors.

[0032] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0033] The preparation method of this invention is simple. The manganese oxide / indium tin oxide composite material prepared by this invention has nanoparticles on its surface, and has a large specific capacitance compared with other manganese oxide nanomaterials or composite materials. The specific capacitance reaches 959 F / g at a current density of 1 A / g. Attached Figure Description

[0034] Figure 1 The image is a scanning electron microscope image of the electrode sheet obtained in step (2) of Example 1.

[0035] Figure 2 The image is a scanning electron microscope image of the electrode sheet obtained in step (3) of Example 1.

[0036] Figure 3 and 4 The image is a scanning electron microscope image of the electrode material obtained in step (4) of Example 1.

[0037] Figure 5 The cyclic voltammetry curves of the electrode material obtained in step (4) of Example 1 at scan rates of 5mV / s, 10mV / s, 20mV / s, 50mV / s, 100 mV / s, 200 mV / s, 300 mV / s, 400 mV / s, and 500 mV / s are shown.

[0038] Figure 6 The graph shows the charge-discharge curves of the electrode material obtained in step (4) of Example 1 under different current densities.

[0039] Figure 7 The graph shows a comparison of the charge-discharge curves of the electrode material obtained in step (4) of Example 1 and the electrode obtained in step (4) of Comparative Example 1 at a current density of 1 A / g. As can be seen from the graph, the electrode obtained under this condition has a longer discharge time, indicating that the electrode has superior capacitance performance.

[0040] Figure 8 The figure shows a comparison of the AC impedance spectra of the electrode material obtained in step (4) of Example 1 and the electrode obtained in step (4) of Comparative Example 1. As can be seen from the figure, the in-situ composite indium tin oxide under electrochemical cycling has a larger curve slope and a smaller real / imaginary impedance in the low-frequency region, indicating that the electrode obtained by in-situ hybridization induced by electrochemical cycling has a faster ion migration rate and a smaller impedance.

[0041] Figure 9 , 10 11 are scanning electron microscope images of the electrode material obtained in step (4) of Example 2.

[0042] Figure 12 and 13The image shows a scanning electron microscope (SEM) image of the electrode material obtained in step (4) of Example 3.

[0043] Figure 14 , 15 16 and 17 are scanning electron microscope images of the electrode material obtained in step (4) of Example 4.

[0044] Figure 18 and 19 The image shows a scanning electron microscope (SEM) image of the electrode material obtained in step (4) of Example 5.

[0045] Figure 20 , 21 22 and 23 are scanning electron microscope images of the electrode material obtained in step (4) of Example 6.

[0046] Figure 24 , 25 26 are scanning electron microscope images of the electrodes obtained in step (4) of Comparative Example 1.

[0047] Figure 27 and 28 The image shows a scanning electron microscope (SEM) image of the electrode material obtained in step (4) of Comparative Example 2.

[0048] Figure 29 The figures show a comparison of the AC impedance spectra of the electrode materials obtained in step (4) of Example 1 and Comparative Example 2. As can be seen from the figures, the electrode obtained by electrochemical cycling after obtaining manganese oxide and then hybridizing indium tin oxide has a larger curve slope and a smaller real / imaginary impedance in the low-frequency region compared to the electrode obtained by first preparing manganese oxide / indium tin oxide composite and then electrochemically cycling. This indicates that the electrode obtained by electrochemical cycling after obtaining manganese tetroxide and then compositing indium tin oxide is closer to the ideal capacitor and has a smaller impedance.

[0049] Figure 30 The graph shows a comparison of the charge-discharge curves of the electrode material obtained in step (4) of Example 1 and the electrode obtained in step (4) of Comparative Example 1 at a current density of 1 A / g. As can be seen from the graph, the electrode obtained under the indium tin oxide (ITO) condition has a longer discharge time, indicating that the electrode obtained by electrochemical cycling and in-situ recombination of ITO after obtaining manganese oxide has superior capacitance performance. Simultaneously, the more symmetrical charge-discharge curves indicate that this electrode has superior rate performance. Detailed Implementation

[0050] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0051] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or conditions recommended by the manufacturer. All raw materials and reagents used, unless otherwise specified, are commercially available conventional products.

[0052] Example 1

[0053] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 500°C for 4 h to obtain oxidized carbon fiber.

[0054] 2) The oxidized carbon fiber was placed in a 4 mg / mL potassium permanganate solution and hydrothermally reacted at 160℃ for 6 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0055] 3) Prepare a manganese acetate solution with a mass concentration of 7 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 1:8:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 180℃ for 5 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0056] 4) The obtained manganese oxide electrode material was subjected to charge-discharge cycles 20 times in a 1 mol / L sodium sulfate electrolyte containing 0.1 mg / mL indium tin oxide within a positive voltage window of 0 to 0.8 V (i.e., the lower limit of the voltage was set to 0 and the upper limit to 0.8 V). After the cycle was completed, it was repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0057] Example 2

[0058] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 400°C for 5 h to obtain oxidized carbon fiber.

[0059] 2) The oxidized carbon fiber was placed in a 3 mg / mL potassium permanganate solution and hydrothermally reacted at 180℃ for 4 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0060] 3) Prepare a manganese acetate solution with a mass concentration of 5 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 2:7:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 140℃ for 8 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0061] 4) The obtained manganese oxide electrode material was subjected to 800 charge-discharge cycles in a 6 mol / L sodium sulfate electrolyte containing 0.02 mg / mL indium tin oxide within a positive voltage window of 0 to 0.9 V (i.e., the lower limit of the voltage was set to 0 and the upper limit to 0.9 V). After the cycle was completed, it was repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0062] Example 3

[0063] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 700°C for 2 h to obtain oxidized carbon fiber.

[0064] 2) The oxidized carbon fiber was placed in a 1 mg / mL potassium permanganate solution and hydrothermally reacted at 140℃ for 8 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0065] 3) Prepare a manganese acetate solution with a mass concentration of 8 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 4:7:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 120℃ for 8 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0066] 4) The obtained manganese oxide electrode material was subjected to charge-discharge cycles for 2000 times in a 0.5 mol / L sodium sulfate electrolyte containing 0.06 mg / mL indium tin oxide within a positive voltage window of 0 to 0.5 V (i.e., the lower limit of the voltage is set to 0 and the upper limit is set to 0.5 V). After the cycle was completed, it was repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0067] Example 4

[0068] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 300°C for 6 h to obtain oxidized carbon fiber.

[0069] 2) The oxidized carbon fiber was placed in a 1 mg / mL potassium permanganate solution and hydrothermally reacted at 140℃ for 8 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0070] 3) Prepare a manganese acetate solution with a mass concentration of 2 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 1:3:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 190℃ for 5 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0071] 4) The obtained manganese oxide electrode material was subjected to 80 charge-discharge cycles in a 0.3 mol / L sodium sulfate electrolyte containing 0.9 mg / mL indium tin oxide within a positive voltage window of 0 to 1.0 V (i.e., the lower limit of the voltage was set to 0 and the upper limit to 1.0 V). After the cycle was completed, the material was repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0072] Example 5

[0073] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 600℃ for 6 h to obtain oxidized carbon fiber.

[0074] 2) The oxidized carbon fiber was placed in a 9 mg / mL potassium permanganate solution and hydrothermally reacted at 190℃ for 5 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0075] 3) Prepare a manganese acetate solution with a mass concentration of 3 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 3:8:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 160℃ for 5 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0076] 4) The obtained manganese oxide electrode material was subjected to 3000 charge-discharge cycles in a 10 mol / L sodium sulfate electrolyte containing 0.09 mg / mL indium tin oxide within a positive voltage window of 0 to 1.1 V (i.e., the lower limit of the voltage was set to 0 and the upper limit to 1.1 V). After the cycle was completed, the material was repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0077] Example 6

[0078] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 700°C for 6 h to obtain oxidized carbon fiber.

[0079] 2) The oxidized carbon fiber was placed in a 3 mg / mL potassium permanganate solution and hydrothermally reacted at 170℃ for 6 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0080] 3) Prepare a manganese acetate solution with a mass concentration of 2 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 1:7:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 160℃ for 7 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0081] 4) The obtained manganese oxide electrode material was subjected to 2000 charge-discharge cycles in a 0.8 mol / L sodium sulfate electrolyte containing 0.8 mg / mL indium tin oxide within a positive voltage window of 0 to 0.7 V (i.e., the lower limit of the voltage was set to 0 and the upper limit to 0.7 V). After the cycle was completed, the material was repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0082] Comparative Example 1

[0083] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 500°C for 4 h to obtain oxidized carbon fiber.

[0084] 2) The oxidized carbon fiber was placed in a 4 mg / mL potassium permanganate solution and hydrothermally reacted at 160℃ for 6 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0085] 3) Prepare a manganese acetate solution with a mass concentration of 7 mg / mL by adding manganese acetate to ethanol, ethylene glycol and water in a volume ratio of 1:8:1. Place the electrode sheet from step 2) in the manganese acetate solution and then perform a hydrothermal reaction at 180℃ for 5 h to grow manganese tetroxide. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the manganese oxide electrode material.

[0086] 4) The obtained manganese oxide electrode material is charged and discharged 20 times in a 1 mol / L sodium sulfate electrolyte with a positive voltage window of 0 to 0.8 V (i.e., the lower limit of the voltage is set to 0 and the upper limit is set to 0.8 V). After the cycle is completed, it is repeatedly washed with deionized water and then dried to obtain the manganese dioxide electrode material.

[0087] Comparative Example 2

[0088] 1) The carbon fiber was ultrasonically washed in anhydrous ethanol, then washed with deionized water and dried; the dried carbon fiber was heated in air at 500°C for 4 h to obtain oxidized carbon fiber.

[0089] 2) The oxidized carbon fiber was placed in a 4 mg / mL potassium permanganate solution and hydrothermally reacted at 160℃ for 6 h to grow manganese dioxide. After repeated washing with deionized water, it was dried to obtain the electrode sheet.

[0090] 3) Prepare a manganese acetate solution with a mass concentration of 7 mg / mL by adding manganese acetate in a volume ratio of ethanol, ethylene glycol and water of 1:8:1. Add indium tin oxide and stir until homogeneous. The concentration of indium tin oxide in the mixed solution is 0.1 mg / mL. Then, perform a hydrothermal reaction at 180℃ for 5 h. After the system cools to room temperature, remove the electrode, wash it repeatedly with deionized water and dry it to obtain the electrode.

[0091] 4) The electrode obtained in step 3) is charged and discharged 20 times in a 1 mol / L sodium sulfate electrolyte with a positive voltage window of 0 to 0.8 V (i.e., the lower limit of the voltage is set to 0 and the upper limit is set to 0.8 V). After the cycle is completed, it is repeatedly washed with deionized water and then dried to obtain the manganese dioxide / indium tin oxide electrode material.

[0092] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a manganese oxide / indium tin oxide composite material, characterized in that, Includes the following steps: (1) After cleaning and drying the carbon fiber, it is oxidized in air to obtain oxidized carbon fiber; (2) Place the carbon dioxide from step (1) in a potassium permanganate solution and grow manganese dioxide by hydrothermal reaction. Then wash and dry to obtain an electrode sheet. (3) Place the electrode sheet from step (2) in a manganese acetate solution to perform a hydrothermal reaction to grow manganese tetroxide, clean and dry it to obtain manganese oxide electrode material; (4) The manganese oxide electrode material from step (3) is subjected to charge-discharge cycle treatment in an electrolyte containing indium tin oxide, then cleaned and dried to obtain the manganese oxide / indium tin oxide composite material.

2. The preparation method according to claim 1, characterized in that, In step (4), the concentration of indium tin oxide in the electrolyte is 0.01–1 mg / mL, more preferably 0.02–0.9 mg / mL; And / or, the electrolyte containing indium tin oxide in step (4) is a sodium sulfate electrolyte containing indium tin oxide, wherein the concentration of sodium sulfate is 0.1 to 10 mol / L.

3. The preparation method according to claim 1, characterized in that, The number of charge-discharge cycles in step (4) is 4 to 5000 times, more preferably 20 to 3000 times.

4. The preparation method according to claim 1, characterized in that, The window voltage for the charge-discharge cycle in step (4) is 0 to 1.2 V.

5. The preparation method according to claim 1, 2, 3, or 4, characterized in that, The oxidation treatment temperature in step (1) is 200-700℃, more preferably 300-700℃; the oxidation treatment time is 1-6 h, more preferably 2-6 h.

6. The preparation method according to claim 1, 2, 3, or 4, characterized in that, The concentration of the potassium permanganate solution in step (2) is 1–10 mg / mL, more preferably 1–9 mg / mL; And / or, the temperature of the hydrothermal reaction in step (2) is 140 to 190°C, and the time of the hydrothermal reaction is 2 to 8 h, more preferably 4 to 8 h.

7. The preparation method according to claim 1, 2, 3, or 4, characterized in that, In step (3), the concentration of manganese acetate in the manganese acetate solution is 1-10 mg / mL, more preferably 2-8 mg / mL; And / or, the temperature of the hydrothermal reaction in step (3) is 120-200°C, more preferably 120-190°C; the time of the hydrothermal reaction is 4-8 h, more preferably 5-8 h.

8. The preparation method according to claim 1, 2, 3, or 4, characterized in that, The manganese acetate solution in step (3) is prepared from manganese acetate, ethanol, ethylene glycol and water; The volume ratio of ethanol, ethylene glycol and water is (1-4):(2-8):1, more preferably (1-4):(3-8):

1.

9. A manganese oxide / indium tin oxide composite material prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the manganese oxide / indium tin oxide composite material according to claim 9 in a supercapacitor.

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