Carbon-coated, potassium-doped manganese dioxide zinc battery cathode material, and preparation method and application thereof

Abstract

The application discloses a kind of carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material and preparation method thereof, first, potassium permanganate aqueous solution is mixed with anhydrous ethanol, then hydrothermal reaction is carried out at 140-160 DEG C, the obtained reaction product is washed, dried, to obtain precursor;The volume ratio of the potassium permanganate solution and anhydrous ethanol is (11-35):1;Then the precursor is sintered at 350-450 DEG C, and the carbon-coated, potassium-doped β-MnO2 zinc battery positive electrode material is obtained.The zinc battery prepared by the carbon-coated, potassium-doped β-MnO2 zinc battery positive electrode material prepared by the application meets the industrialization standard, has higher specific capacity, and has long attenuation period.

Description

Technical Field

[0001] This invention belongs to the field of battery materials, and relates to zinc-ion battery cathode materials, particularly to a carbon-coated, potassium-doped manganese dioxide zinc battery cathode material, its preparation method, and its application. Background Technology

[0002] Aqueous zinc-ion batteries have been widely studied due to their low cost, high efficiency, and low toxicity. Among them, manganese dioxide is abundant, inexpensive, and exhibits good electrochemical activity, making it widely used in zinc-ion batteries. However, manganese dioxide has the following drawbacks during the charge-discharge process of zinc-ion batteries: ①Zn 2+ The reversible insertion and extraction of manganese dioxide leads to structural collapse and dissolution of surface elements; ② Manganese dioxide has poor electrical and ionic conductivity. Doping has become one of the methods to improve the inherent shortcomings of manganese dioxide.

[0003] However, current research mainly focuses on metal cation-doped manganese dioxide systems, while there are relatively few doped materials synthesized directly.

[0004] Patent application CN95195471.7 discloses a method for synthesizing manganese oxide materials with added alkali metals and an electrode for an electrochemical battery. The method first prepares a mixed precipitate of manganese hydroxide and lithium hydroxide, then adds lithium peroxide, and reacts it in nitrogen at 450°C for 30 hours to obtain manganese oxide with LiMnO2 composition. However, this method does not directly synthesize doped manganese oxide materials and the preparation process is cumbersome. The lithium-containing raw materials required for the prepared LiMnO2 are expensive, and the loading is small, limiting its practical significance. In contrast, this invention achieves approximately 15 mg / cm³ in button cell testing. 3 The above load values ​​are of great significance for engineering reference. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a carbon-coated, potassium-doped manganese dioxide zinc battery cathode material and its preparation method, which uses a simple process to prepare β-MnO2 with higher specific capacity and longer decay period.

[0006] Another object of the present invention is to provide the application of the above-mentioned carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material.

[0007] The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material provided by the present invention includes the following steps:

[0008] S1 Preparation of precursor

[0009] A potassium permanganate aqueous solution was mixed with anhydrous ethanol and then subjected to a hydrothermal reaction at 140-160℃. The resulting reaction product was washed and dried to obtain a precursor. The volume ratio of the potassium permanganate aqueous solution to anhydrous ethanol was (11-35):1.

[0010] S2 Synthesis of carbon-coated, potassium-doped β-MnO2

[0011] The precursor is sintered at 350-450℃ to obtain carbon-coated, potassium-doped β-MnO2 zinc battery cathode material.

[0012] In step S1 above, potassium permanganate and anhydrous ethanol are used as raw materials to prepare a Mn-containing precursor via a hydrothermal reaction. In this way, the prepared precursor contains Mn-containing compounds such as γ-MnOOH. The precursor can serve as a nanorod template for the target product β-MnO2. The potassium permanganate aqueous solution is obtained by dissolving potassium permanganate in deionized water, with a potassium permanganate concentration of 35-45 mg / mL. The hydrothermal reaction time is preferably 18-24 h. After the hydrothermal reaction, the product can be cooled to room temperature in the furnace, and then washed multiple times with anhydrous ethanol and deionized water. The washed product is first dried in a low-temperature oven at 60-80℃ for 6-12 h, and then dried in a vacuum drying oven at a vacuum degree of 0.01-0.1 MPa and 100-150℃ for 6-8 h to obtain the precursor.

[0013] In step S2 above, the precursor can be crushed first and then sintered to ensure the uniformity of calcination. During the sintering process, the temperature is first raised to 350-450℃ at 3-5℃ / min and held for 3-5 hours. Then, it is cooled to room temperature with the furnace to obtain carbon-coated, K-doped β-MnO2 zinc battery cathode material.

[0014] This invention also provides the application of the above-mentioned carbon-coated, K-doped β-MnO2 zinc battery cathode material in the preparation of zinc batteries.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) The present invention first uses potassium permanganate solution and anhydrous ethanol as raw materials to prepare a precursor through hydrothermal reaction. The precursor is then calcined to obtain carbon-coated and potassium-doped β-MnO2 zinc battery cathode material. The preparation process is simple and suitable for industrial application.

[0017] (2) The β-MnO2 zinc battery cathode material prepared in this invention contains K ions, which can change the β-MnO2 interlayer spacing and facilitate charge transfer.

[0018] (3) The zinc battery prepared using the carbon-coated, potassium-doped β-MnO2 zinc battery cathode material prepared in this invention meets the industrialization standards and exhibits a higher specific capacity than other high-load button batteries. Attached Figure Description

[0019] Figure 1 The XRD test results are for the carbon-coated, K-doped β-MnO2 zinc battery cathode materials prepared in Examples 1-4.

[0020] Figure 2 The SEM test results are for the carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in Example 1.

[0021] Figure 3 The TEM test results are for the carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in Example 1.

[0022] Figure 4 The specific capacity test results are for the zinc battery prepared in Example 1.

[0023] Figure 5 The results show the internal resistance test results of the zinc battery prepared in Example 1. Detailed Implementation

[0024] The technical solutions of various embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are part of the present invention.

[0025] Examples 1-4

[0026] The preparation method of the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material provided in Examples 1-4 includes the following steps:

[0027] S1 Preparation of precursor

[0028] Dissolve 2.93g of potassium permanganate in 64.5-68mL of deionized water, then add 2-5.5mL of anhydrous ethanol and stir for 30min; then add the resulting mixture to a reaction vessel and carry out a hydrothermal reaction at 150℃ for 20h.

[0029] The reaction product showed solid-liquid separation, and the precipitate was brown. The reaction product was washed with water and anhydrous ethanol in sequence by centrifugation, three times with each washing solution, at a centrifugation rate of 4000 rpm and a centrifugation time of 5 min.

[0030] The washed product was first dried in a low-temperature oven at 60°C for 6 hours, and then dried in a vacuum drying oven at 100°C under a vacuum of 0.03 MPa for 6 hours to obtain the precursor.

[0031] S2 Synthesis of carbon-coated, potassium-doped β-MnO2

[0032] The precursor was first crushed and then placed in a tube furnace through a crucible. The tube furnace was heated to 400°C at a rate of 5°C / min and held for 3 hours. After cooling with the furnace, a black solid was obtained, which is the carbon-coated, K-doped β-MnO2 zinc battery cathode material.

[0033] The amounts of deionized water and anhydrous ethanol used in Examples 1-4 above are shown in the table below.

[0034]

[0035] XRD tests were performed on the carbon-coated, K-doped β-MnO2 zinc battery cathode materials prepared in Examples 1-4. The test results are as follows: Figure 1 As shown in the figure, the material prepared by the method of this invention is basically consistent with the standard β-MnO2 XRD pattern.

[0036] The carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in Example 1 was subjected to SEM testing, and the test results are as follows: Figure 2 As shown, from Figure 2 It can be seen that the prepared β-MnO2 zinc battery cathode material has a nanorod structure, and a layer of material can be clearly seen on its surface.

[0037] The carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in Example 1 was subjected to TEM testing, and the test results are as follows: Figure 3 As shown in the figure, the prepared β-MnO2 zinc battery cathode material contains Mn, O, K, and C elements, proving that K has been successfully doped. Figure 2 As can be seen, carbon is coated on the surface of the nanorod-shaped β-MnO2. The carbon coating facilitates the reversible deposition of active materials and plays a certain role in the charge and discharge stability of the battery.

[0038] Example 5

[0039] The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material provided in this embodiment includes the following steps:

[0040] S1 Preparation of precursor

[0041] Dissolve 2.93 g of potassium permanganate in 65 mL of deionized water, then add 5 mL of anhydrous ethanol and stir for 30 min; then add the resulting mixture to a reaction vessel and carry out a hydrothermal reaction at 140 °C for 24 h.

[0042] The reaction product showed solid-liquid separation, and the precipitate was brown. The reaction product was washed with water and anhydrous ethanol in sequence by centrifugation, three times with each washing solution, at a centrifugation rate of 4000 rpm and a centrifugation time of 5 min.

[0043] The washed product was first dried in a low-temperature oven at 60°C for 12 hours, and then dried in a vacuum drying oven at 100°C under a vacuum of 0.01 MPa for 8 hours to obtain the precursor.

[0044] S2 Synthesis of carbon-coated, potassium-doped β-MnO2

[0045] The precursor was first crushed and then placed in a tube furnace through a crucible. The tube furnace was heated to 350°C at a rate of 3°C / min and held for 5 hours. After cooling with the furnace, a black solid was obtained, which is the carbon-coated, K-doped β-MnO2 zinc battery cathode material.

[0046] Example 6

[0047] The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material provided in this embodiment includes the following steps:

[0048] S1 Preparation of precursor

[0049] Dissolve 2.93 g of potassium permanganate in 66.5 mL of deionized water, then add 3.5 mL of anhydrous ethanol and stir for 30 min. Then add the resulting mixture to a reaction vessel and carry out a hydrothermal reaction at 160 °C for 18 h.

[0050] The reaction product showed solid-liquid separation, and the precipitate was brown. The reaction product was washed with water and anhydrous ethanol in sequence by centrifugation, three times with each washing solution, at a centrifugation rate of 4000 rpm and a centrifugation time of 5 min.

[0051] The washed product was first dried in a low-temperature oven at 80°C for 6 hours, and then dried in a vacuum drying oven at 150°C under a vacuum of 0.1 MPa for 6 hours to obtain the precursor.

[0052] S2 Synthesis of carbon-coated, potassium-doped β-MnO2

[0053] The precursor was first crushed and then placed in a tube furnace through a crucible. The tube furnace was heated to 450°C at a rate of 5°C / min and held for 3 hours. After cooling with the furnace, a black solid was obtained, which is the carbon-coated, K-doped β-MnO2 zinc battery cathode material.

[0054] Application examples

[0055] This application example uses the carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in Example 1 to prepare a zinc battery. The specific steps are as follows:

[0056] Step 1: The carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in Example 1 is ball-milled for 10 minutes to obtain powder for later use.

[0057] Step 2: The black powder, as the positive electrode active material, is mixed with binder PTFE (polytetrafluoroethylene) and conductive material (graphite, etc.) in a mass ratio of 6:1:1, and then pressed into a positive electrode disc with a size of 12×12mm, a thickness of 170μm, and a weight of 25mg.

[0058] Step 3: Use zinc foil to make a negative electrode of the same size as the positive electrode disc;

[0059] Step 4: Add the positive electrode, zinc sulfonate electrolyte (a 3 mol / L zinc sulfonate aqueous solution), separator, zinc negative electrode, gasket, and spring to the button cell in sequence; then press the button cell to obtain a zinc battery.

[0060] Zinc battery testing method: After the zinc battery is left to stand for 10 hours, charge-discharge cycle tests are performed using Xinwei instruments within the voltage range of 0.8-1.9V, at a rate of 2.5mA / cm. 2 A constant current charge-discharge experiment was conducted within this voltage range, and the specific capacity and internal resistance test results are as follows: Figure 4 and Figure 5 As shown in the figure, the zinc battery made with the carbon-coated, K-doped β-MnO2 zinc battery cathode material prepared in this invention has a specific capacity of up to 230 mAh / g, and its internal resistance remains low after 10 cycles, maintaining around 20 Ω. It also exhibits good stability after 100 cycles.

[0061] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for preparing a carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material, characterized in that, Includes the following steps: S1 Preparation of precursor A potassium permanganate aqueous solution was mixed with anhydrous ethanol and then subjected to a hydrothermal reaction at 140-160℃. The resulting reaction product was washed and dried to obtain a precursor. The volume ratio of the potassium permanganate aqueous solution to anhydrous ethanol was (11-35):

1. S2 Synthesis of carbon-coated, potassium-doped β-MnO2 The precursor is sintered at 350-450℃ to obtain carbon-coated, potassium-doped β-MnO2 zinc battery cathode material.

2. The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material according to claim 1, characterized in that, In step S1, the potassium permanganate aqueous solution is obtained by dissolving potassium permanganate in deionized water, wherein the concentration of potassium permanganate is 35-45 mg / mL.

3. The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material according to claim 1, characterized in that, The hydrothermal reaction time is 18-24 hours.

4. The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material according to claim 3, characterized in that, After the hydrothermal reaction was completed, the furnace was cooled to room temperature, and then washed multiple times with anhydrous ethanol and deionized water.

5. The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material according to claim 4, characterized in that, The washed product is first dried in a low-temperature oven at 60-80℃ for 6-12 hours, and then dried in a vacuum drying oven at 100-150℃ under a vacuum of 0.01-0.1MPa for 6-8 hours to obtain the precursor.

6. The method for preparing the carbon-coated, potassium-doped manganese dioxide zinc electrode positive electrode material according to claim 1, characterized in that, In step S2, during the sintering process, the temperature is first raised to 350-450℃ at 3-5℃ / min and held for 3-5 hours. Then, the temperature is cooled to room temperature with the furnace to obtain carbon-coated, K-doped β-MnO2 zinc battery cathode material.

7. The application of the carbon-coated, potassium-doped β-MnO2 zinc battery cathode material prepared by the method according to any one of claims 1 to 6 in the preparation of zinc batteries.

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