A Mn x O y Preparation method, Mn x O y Preparation method of / rGO composite electrode sheet, composite electrode sheet and application

Abstract

The application provides a Mn x O y Preparation method, Mn x O y / rGO composite electrode sheet preparation method, composite electrode sheet and application. The application adopts simple acid-base neutralization reaction and salt replacement reaction to prepare a series of metal organic coordination compounds, and obtains metal manganese oxide through high-temperature calcination under different atmospheres, and then generates rGO on the metal manganese oxide to prepare Mn x O y / rGO composite material. The Mn x O y / rGO material prepared by the application maintains the porosity of the metal organic coordination compound, is beneficial to the infiltration of electrolyte, different metal organic coordination compounds obtain different crystal structures under different atmospheres, and the rGO improves the conductivity of the material. The Mn3O4 / rGO material in the application is used as a positive electrode of a zinc ion battery, and 86.9 % of capacity retention and good rate performance can be obtained under the circulation of 100 cycles at a current density of 500 mA g ‑1 .

Description

Technical Field

[0001] This invention relates to composite electrode technology, and more particularly to a Mn x O y Preparation method, Mn x O y / rGO composite electrode preparation method, composite electrode and application. Background Technology

[0002] Aqueous zinc-ion batteries have become increasingly popular due to their advantages such as high theoretical specific capacity, relatively low redox potential, wide operating voltage window (0-2.0V), low cost, high safety, and environmental friendliness. 2+ Intercalated rechargeable zinc-ion batteries have attracted widespread attention from scientific researchers. Currently reported cathode materials for aqueous zinc-ion batteries mainly include manganese-based oxides, vanadium-based compounds, Prussian blue analogs, and organic compounds. Among these, manganese-based oxides, due to their tunnel or layered structure, allow Zn... 2+ The reversible insertion / extraction of ions has led to a significant amount of research focusing on MnO2 as a cathode material for zinc-ion batteries. Although MnO2 possesses diverse structures, the large size of hydrated zinc ions repeatedly inserts and extracts within the MnO2 matrix during charge and discharge, inevitably causing substantial volume changes in the matrix structure. This can even lead to severe phase transitions and structural collapse, resulting in rapid capacity decay during cycling. Furthermore, common methods for preparing manganese-based oxides include oxidation, reduction, electrolysis, and thermal decomposition. These methods are relatively complex and require strong oxidizing or reducing agents. Summary of the Invention

[0003] The purpose of this invention is to address the problem of complex preparation of existing manganese-based materials by proposing a Mn... x O y The preparation method has the advantages of simple preparation, environmental friendliness, low cost and controllable structure.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is: a Mn x O y The preparation method includes the following steps:

[0005] Step 1. Dissolve the alkali metal hydroxide in water, add benzoic acid and / or benzoic acid derivatives, and stir at room temperature until the solution is completely dissolved;

[0006] Step 2. Dissolve the manganese salt in water and add it to the solution from Step 1 within 10 minutes. Stir the reaction at room temperature to obtain a brown precipitate. Filter the precipitate under vacuum, wash it with deionized water and ethanol, and dry it to obtain manganese benzoate.

[0007] Step 3. Anneal the manganese benzoate to obtain Mn. x O y .

[0008] Further, the alkali metal hydroxide mentioned in step 1 is one or more of lithium hydroxide hydrate, sodium hydroxide, and potassium hydroxide.

[0009] Further, the benzoic acid mentioned in step 1 is one or more of terephthalic acid, phthalic acid, trimesic acid, and pyromellitic acid. The benzoic acid derivative is one or more of 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, and 3,4,5-trihydroxybenzoic acid.

[0010] Further, the molar ratio of the alkali metal hydroxide to benzoic acid and / or benzoic acid derivatives in step 1 is 4 to 1:1, preferably a mass ratio of 2:1.

[0011] Furthermore, the stirring reaction time in step 1 is 0.1 to 1 hour, preferably 0.4 to 0.6 hours.

[0012] Further, the manganese salt mentioned in step 2 is one or more of manganese sulfate monohydrate (MnSO4·H2O), manganese chloride, manganese sulfate, manganese nitrate, and manganese acetate.

[0013] Further, the molar ratio of manganese salt and benzoic acid and / or benzoic acid derivative in step 2 is 1-4:4-1, preferably a mass ratio of 1-2:2-1.

[0014] Furthermore, the stirring reaction time in step 2 is 6 to 20 hours, preferably 10 to 12 hours.

[0015] Further, in step 2, the sample is washed three times each with deionized water and ethanol.

[0016] Furthermore, in step 2, the drying temperature is 60–90°C, and the drying time is 6–12 hours.

[0017] Furthermore, the annealing treatment in step 3 is performed at a temperature of 400–700°C for 1–4 hours.

[0018] Furthermore, the annealing described in step 3 is performed in a muffle furnace or a tube furnace.

[0019] Furthermore, taking the preparation of Mn3O4 as an example, its preparation method includes the following steps:

[0020] Step 1. Dissolve lithium hydroxide monohydrate (LiOH·H2O) in water, add terephthalic acid, and stir the reaction at room temperature;

[0021] Step 2. Dissolve manganese sulfate monohydrate (MnSO4·H2O) in water and add it dropwise to the solution in Step 1 over 10 minutes using a dropper. Stir the reaction at room temperature to obtain a brown precipitate. Finally, filter the precipitate under vacuum, wash it with deionized water and ethanol, and dry it to obtain manganese terephthalate.

[0022] Step 3. Anneal manganese terephthalate to obtain Mn3O4.

[0023] Further, the mass ratio of hydrated lithium hydroxide (LiOH·H2O) to terephthalic acid in step 1 is 3 to 1:1, preferably 2:1.

[0024] Furthermore, the stirring reaction time in step 1 is 1 to 6 hours, preferably 2 hours.

[0025] Furthermore, the molar ratio of manganese sulfate monohydrate (MnSO4·H2O) in step 2 to terephthalic acid in step 1 is 1-2:2-1, preferably a mass ratio of 1:1.

[0026] Furthermore, the stirring reaction time in step 2 is 6 to 20 hours, preferably 12 hours.

[0027] Further, in step 2, the sample is washed three times each with deionized water and ethanol.

[0028] Furthermore, in step 2, the drying temperature is 60-90℃ and the time is 6-12 hours.

[0029] Furthermore, the annealing treatment in step 3 is performed at a temperature of 400–700°C for 1–4 hours.

[0030] Furthermore, the annealing described in step 3 is completed in a muffle furnace.

[0031] Another object of the present invention also discloses a Mn x O y The method for preparing / rGO composite electrode sheets has the advantages of simple preparation, green and environmentally friendly, and high reproducibility.

[0032] To achieve the above objectives, the technical solution adopted by the present invention is: a Mn x O y The method for preparing / rGO composite electrode sheets includes the following steps:

[0033] S1. Mn x O y The GO suspension (graphite oxide suspension) was dispersed in water, ascorbic acid was added, and ammonia was added dropwise to adjust the pH to 9-11;

[0034] S2. The S1 solution was reacted in a sealed environment at 60-90℃ for 1-4 hours, filtered, washed with water and dried to prepare the Mn3O4 / rGO composite material;

[0035] S3. The above Mn x O y / rGO composite material is mechanically compressed into a film, and then the sample is cut to obtain Mn x O y / rGO composite electrode sheet.

[0036] Furthermore, the mass ratio of Mn3O4, GO suspension and ascorbic acid in S1 is 1-2:1:5-10, preferably 2:1:10.

[0037] Furthermore, the graphene oxide content in the GO suspension described in S1 is 1–15 mg / ml. -1 The preferred content is 10mg / ml. -1 .

[0038] Furthermore, as described in S2, the S1 solution is sealed and placed in an oven at 60–90°C for 1–4 hours.

[0039] Furthermore, the number of washing cycles in S2 is 3.

[0040] Furthermore, the drying temperature described in S2 is 60–100°C, and the drying time is 6–15 hours.

[0041] Furthermore, S3 will Mn x O y / rGO composite material is mechanically compressed for 2-10 minutes under a pressure of 5-10 MPa to form a film.

[0042] Furthermore, S3 cut the sample into Mn particles with a diameter of 12 mm. x O y / rGO composite electrode sheet.

[0043] Another object of the present invention also discloses a Mn x O y The / rGO composite electrode sheet was prepared using the method described above.

[0044] Another object of the present invention also discloses a Mn x O y Application of / rGO composite electrode sheets in the field of zinc-ion batteries.

[0045] Furthermore, zinc sheets are used as the negative electrode, glass fibers as the diaphragm, and an aqueous solution of zinc sulfate (2M) as the electrolyte. x O y / rGO composite electrode sheet is used as the positive electrode and assembled into a coin cell in an air environment.

[0046] The assembled batteries were placed on a hydraulic button cell sealing machine and sealed under pressure. They were then left to stand at room temperature for 12 hours before being tested for cyclic voltammetry, rate performance, and long-cycle performance. Electrochemical tests revealed that using the Mn3O4 / rGO composite electrode as the positive electrode exhibited excellent rate performance and capacity retention.

[0047] This invention Mn x O y Preparation method, Mn x O y The preparation method of / rGO composite electrode sheet, the composite electrode sheet and its application, involve a Mn derived from a metal-organic coordination compound. x O y The preparation method of the reduced graphene oxide (rGO) composite material and its electrochemical performance in zinc-ion batteries are discussed. Specifically, this invention has the following advantages compared with existing technologies:

[0048] 1) This invention uses a simple dissolution-precipitation method to synthesize manganese-containing organic coordination compounds at room temperature, and uses these compounds as precursors to prepare Mn in different valence states by high-temperature calcination in different atmospheres. x O y Mn prepared by this method x O y Materials can be obtained in multiple valence states of Mn by changing the organic ligands / preparation conditions. x O y Moreover, it retains its porous properties, providing more active sites and specific surface area for electrochemical reactions.

[0049] 2) This invention uses a simple hydrothermal method to prepare Mn x O y Mn, when combined with rGO, yielded excellent aqueous zinc-ion batteries. x O y / rGO composite electrode material. On the one hand, this method does not require the additional use of current collectors, Mn x O y The uniform dispersion of the material during in-situ formation on rGO allows for the uniform dispersion of Mn. x O y The closer contact between the rGO and the material further reduces the contact resistance of the material itself. On the other hand, the conductive network can also significantly improve the conductivity of the material, which is beneficial for improving the high-rate performance of the battery.

[0050] 3) Organometallic coordination compounds (MMCs) utilize metal ions as binding sites, with organic ligands providing support for 3D spatial extension. They possess advantages such as tunable and controllable structure, abundant porosity, and simple preparation. This invention prepares different MMC structures by controlling the types of organic ligands, thereby producing manganese oxides with different structures. Furthermore, carbon coating is used to improve the stability of the electrode material, resulting in the preparation of Mn... x O y / rGO composite electrode sheets can be used in zinc-ion batteries.

[0051] 4) The Mn obtained by this invention x O y / rGO composite electrode materials exhibit excellent electrochemical performance. The Mn prepared in this invention... x O y rGO materials retain the porosity of organometallic coordination compounds, which is beneficial for electrolyte wetting. Different organometallic coordination compounds exhibit different crystal structures under different atmospheres, and rGO improves the conductivity of the material. For example, when Mn3O4 / rGO material is used as the positive electrode in a zinc-ion battery, it achieves conductivity at 500 mA g. -1 At the specified current density, 86.9% capacity retention and good rate performance can be obtained after 100 cycles. Attached Figure Description

[0052] Figure 1 SEM image of manganese terephthalate;

[0053] Figure 2 This is a SEM image of manganese terephthalate-derived Mn3O4.

[0054] Figure 3 The image shows the XRD pattern of Mn3O4.

[0055] Figure 4 This is a SEM image of Mn3O4 / rGO.

[0056] Figure 5 This is a SEM image of the Mn3O4 / rGO electrode.

[0057] Figure 6 This is a SEM image of the Mn3O4 / C electrode.

[0058] Figure 7 The CV plot is for Zn||Mn3O4 / rGO.

[0059] Figure 8 The rate performance diagram is for Zn||Mn3O4 / rGO.

[0060] Figure 9 The cyclic curve of Zn||Mn3O4 / rGO.

[0061] Figure 10 The log(i)-log(v) curve and fitting plot of Zn||Mn3O4 / rGO. Detailed Implementation

[0062] The present invention will be further described below with reference to the embodiments:

[0063] Example 1

[0064] This embodiment discloses a Mn3O4 / rGO composite flexible electrode. First, a precursor, manganese benzoate, is prepared using a simple acid-base neutralization reaction and a salt substitution reaction. Then, Mn3O4 is prepared by high-temperature calcination in air in a muffle furnace. The method specifically includes the following steps:

[0065] First, 0.05 mol lithium hydroxide monohydrate (LiOH·H2O, 2.1 g) was dissolved in 150 mL of deionized water. Then, 0.025 mol terephthalic acid (TP, 4.15 g) was added, and the mixture was magnetically stirred for 30 min at room temperature. Next, 0.01 mol manganese sulfate monohydrate (MnSO4·H2O, 1.69 g) was dissolved in 50 mL of deionized water and slowly poured into the above solution. The mixture was magnetically stirred for 12 h at room temperature, resulting in a brown precipitate. Finally, the precipitate was filtered under vacuum, washed several times with deionized water and ethanol, and dried in an oven to obtain manganese terephthalate (MnTP). The dried MnTP was placed in a TSX12 high-temperature box-type resistance furnace and heated to 500 °C at a rate of 2 °C / min for pyrolysis for 2 hours. After the furnace temperature cooled to room temperature, the sample was removed, yielding Mn3O4 material.

[0066] The morphology of MnTP and Mn3O4 prepared in Example 1 was tested using scanning electron microscopy (SEM), as follows: Figure 1 and 2 The SEM image shown is shown. As can be seen from the image, the precursor MnTP is spherical. After high-temperature calcination, the resulting Mn3O4 still retains the spherical morphology, but pores appear inside.

[0067] The Mn3O4 prepared in Example 1 of this invention was characterized by XRD, as follows: Figure 3 As shown. After comparison with the Mn3O4 standard card (JCPDS No. 80-0382), the diffraction peaks all matched the card and there were no other impurity peaks, indicating that the material has good crystallinity.

[0068] Example 2

[0069] This embodiment discloses a method for preparing Mn3O4-rGO composite electrode sheets. The specific operation method is as follows:

[0070] Take 0.2g of the Mn3O4 powder prepared in Example 1 and ultrasonically disperse it in 50ml of deionized water. Use a pipette to take 10ml of GO suspension (10mg / ml). -1 Add 1g of ascorbic acid to the above solution, adjust the pH to about 10 by adding ammonia dropwise, and then seal the solution and place it in a 70℃ oven for 2 hours. Then, prepare the Mn3O4 / rGO composite material by vacuum filtration, wash it three times with deionized water, dry it, and mechanically compress the Mn3O4 / rGO sample at 5MPa pressure for 10 minutes to form a film. Finally, cut the sample into 12mm diameter electrode sheets.

[0071] The morphology of Mn3O4 / rGO in Example 2 was tested using SEM, as shown below. Figure 4 As shown in the figure, rGO exhibits a network structure and no spherical Mn3O4 was observed, indicating that Mn3O4 is uniformly dispersed in rGO.

[0072] Example 3

[0073] This embodiment discloses a method for preparing Mn3O4 / rGO composite electrode materials. It is similar to the method for preparing Mn3O4-rGO composite materials in Example 2, except that the Mn3O4 / rGO sample is not directly compressed; instead, a traditional electrode coating method is used. The specific operation is as follows:

[0074] Take the Mn3O4-rGO powder prepared in Example 2, acetylene black and PVDF in a mass ratio of 7:2:1 and place them in a mortar. After grinding them evenly, they are coated onto a titanium foil with a diameter of 12 mm.

[0075] The morphology of Mn3O4 / rGO in Example 3 was tested using SEM, as shown below. Figure 5 As shown in the figure, the entire electrode exhibits some agglomerates, which may be due to uneven dispersion of the active material.

[0076] Example 4

[0077] This embodiment discloses a method for preparing Mn3O4 material grown on carbon cloth. First, an MnTP precursor is grown on treated carbon cloth, and then calcined in a muffle furnace to obtain the final product. The specific steps are as follows:

[0078] Carbon cloth cleaning: First, sonicate the carbon cloth with acetone for 1 hour, then soak it in 1M HCl for 24 hours, and finally clean the carbon cloth with deionized water.

[0079] Precursor preparation: 0.5 mmol LiOH·H₂O and 0.25 mmol terephthalic acid were added to 50 mL of deionized water and magnetically stirred for 30 min at room temperature. Carbon was then arranged in the above solution. 0.1 mmol MnSO₄·H₂O was dissolved in 10 mL of deionized water and slowly added to the above solution. The mixture was allowed to stand at room temperature for 20 h. Finally, the mixture was filtered under vacuum, washed several times with deionized water and ethanol, and dried in an oven to obtain the Mn₃O₄ / C material.

[0080] The morphology of the Mn3O4 / C material in Example 4 was tested using SEM, as shown below. Figure 6 As shown in the figure, the entire electrode Mn3O4 is dispersed on carbon cloth composed of carbon fibers.

[0081] The electrode material obtained in Example 2 was used as an electrode material in an aqueous zinc-ion battery, and relevant electrochemical performance tests were conducted.

[0082] Mn3O4 / rGO was used as the cathode, Whatman GF / A glass fiber membrane as the separator, Zn foil as the anode, and a 2M ZnSO4 aqueous solution of 0.2M MnSO4 as the electrolyte. Electrochemical evaluation was performed by assembling a CR2032 coin cell. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were tested using an electrochemical workstation (Chenhua, CHI660E). Galvanostatic charge-discharge (GCD) performance was obtained using a battery testing system (Neware) at room temperature within a voltage range of 1.0–1.9 V.

[0083] Test result 1:

[0084] Figure 7 The CV curve of the Zn||Mn3O4-rGO battery in Example 2 is shown at 0.2 mV s. -1 At a scan rate of 1.0V-1.9V (vs Zn / Zn) 2+ The test was conducted within the voltage window of [the specified voltage range]. As can be seen from the figure, the CV curve of Mn3O4-rGO shows two pairs of reduction and oxidation peaks, corresponding to Zn [reduction and oxidation peaks]. 2+ The insertion and extraction of Mn3O4 indicate that Mn3O4 can effectively store charge.

[0085] Test result 2:

[0086] Figure 8 The rate performance of the Zn||Mn3O4-rGO battery in Example 2 was measured at 0.1, 0.2, 0.5, 0.8, and 1 A g. -1 The charge-discharge test was performed for 5 cycles at the current density, and then returned to 0.1 A g. -1The circuit was cycled 5 times at the current density. Tests showed that when the current density recovered to 0.1 A g... -1 At that time, the Zn||Mn3O4-rGO battery can be restored to 161.2mAh g. -1 The discharge capacity indicates that the battery has good rate performance, which shows that the material has good conductivity.

[0087] Test result 3:

[0088] Figure 9 The Zn||Mn3O4-rGO battery in Example 2 at 500mA g -1 The Zn||Mn3O4-rGO battery exhibited long-cycle performance at current density, completing 100 cycles. Its maximum discharge capacity was 103 mAh g. -1 After 100 cycles, the capacity reaches 89.5mAh g. -1 The capacity retention rate is 86.9% and the coulomb efficiency is nearly 100%.

[0089] Test result 4:

[0090] Figure 10 The diagram shows the calculated pseudocapacitance of the Zn||Mn3O4-rGO battery in Example 2. Different scan rates (0.1-0.8 mV s) were tested within a voltage range of 1.0-1.9 V. -1 The kinetics of charge storage in the Mn3O4-rGO electrode were investigated using CV curves. By fitting the log function of the peak current and scan rate of the CV curves, it was found that the electrochemical reaction process of Mn3O4-rGO is mainly controlled by diffusion.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of Mn x O y The method for preparing / rGO composite electrode sheets is characterized by, Includes the following steps: (a) Preparation of Mn x O y Step 1. Dissolve the alkali metal hydroxide in water, add benzoic acid and / or benzoic acid derivatives, and stir at room temperature until the solution is completely dissolved; Step 2. Dissolve the manganese salt in water and add it to the solution from Step 1 within 10 min. Stir the reaction at room temperature for 10-12 h to obtain a brown precipitate. Filter the precipitate under vacuum, wash it with deionized water and ethanol, and dry it to obtain manganese benzoate. Step 3. Anneal the manganese benzoate to obtain Mn. x O y ; (II) Preparation of composite electrode sheets S1. Mn x O y Disperse the GO suspension in water, add ascorbic acid, and adjust the pH to 9-11 by adding ammonia. S2. The S1 solution was reacted in a sealed environment at 60–90 °C for 1–4 h, filtered, washed with water, and dried to obtain Mn. x O y / rGO composite materials; S3. The above Mn x O y / rGO composite material is mechanically compressed into a film, and then the sample is cut to obtain Mn x O y / rGO composite electrode sheet.

2. The Mn according to claim 1 x O y The method for preparing / rGO composite electrode sheets is characterized by, The alkali metal hydroxide mentioned in step 1 is one or more of hydrated lithium hydroxide, sodium hydroxide, and potassium hydroxide; And / or, the benzoic acid in step 1 is one or more of terephthalic acid, phthalic acid, pyromellitic acid and pyromellitic acid; And / or, the benzoic acid derivative in step 1 is one or more of 2-hydroxyterephthalic acid, 2,5-dihydroxyterephthalic acid, and 3,4,5-trihydroxybenzoic acid.

3. The Mn according to claim 1 or 2 x O y The method for preparing / rGO composite electrode sheets is characterized by, The molar ratio of the alkali metal hydroxide to benzoic acid and / or benzoic acid derivatives in step 1 is 3 to 1:

1.

4. The Mn according to claim 1 x O y The method for preparing / rGO composite electrode sheets is characterized by, The manganese salt mentioned in step 2 is one or more of manganese sulfate monohydrate, manganese chloride, manganese sulfate, manganese nitrate, and manganese acetate.

5. The Mn according to claim 1 or 4 x O y The method for preparing / rGO composite electrode sheets is characterized by, The mass ratio of the manganese salt in step 2 to the solution in step 1 is 1~2:2~1.

6. The Mn according to claim 1 x O y The method for preparing / rGO composite electrode sheets is characterized by, The graphene oxide content in the GO suspension described in S1 is 1~15 mg / ml. -1 .

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