A kind of manganese oxide polyhedron material for aqueous zinc ion battery and preparation method thereof

Abstract

The invention discloses a manganese oxide polyhedral material for an aqueous zinc ion battery and a preparation method thereof. The method comprises the following steps: dissolving a divalent manganese salt and a chlorate in an aqueous solution of acetic acid, subjecting the obtained mixed solution to a hydrothermal treatment, washing the hydrothermal precipitate, vacuum drying, and then annealing to obtain the manganese oxide polyhedral material. The invention utilizes the weak acidity and surface activity of acetic acid and special atmosphere control to prepare a manganese oxide material having a unique polyhedral structure, and has good zinc storage capacity as a positive electrode material for an aqueous zinc ion battery.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of novel battery materials, and in particular relates to a manganese oxide polyhedron material for aqueous zinc ion batteries and a preparation method thereof. Background Art

[0002] The research and development of green and safe "aqueous metal ion energy storage batteries" can not only continuously improve the safety, economy and environmental adaptability of large-scale energy storage, but also provide technical support for promoting large-scale application of energy storage. Among them, aqueous zinc-ion batteries have become the research focus of large-scale energy storage applications in the future due to their high natural abundance of zinc, high theoretical specific capacity, relatively low redox potential and high safety. However, its energy density is mainly limited by the development of high-performance positive electrode materials. Therefore, the development of high-performance zinc-ion battery positive electrode materials is a very important research direction. Manganese oxide, as a low-valent manganese oxide, is easily electrochemically induced to form manganese defects during the first charging process, which reduces the Zn 2+ The migration energy barrier in the electrode material promotes the Zn 2+ Rapid deintercalation in manganese oxide positive electrode materials activates and enhances the zinc storage capacity and rate performance of manganese oxide.

[0003] There are many methods for preparing manganese oxide, and the resulting materials have different morphologies. Some progress has been made in the field of energy storage, but the positive electrode materials for zinc-ion batteries still have problems such as low capacity and poor stability. In existing studies, manganese oxide is generally doped or coated to improve its electronic structure, conductivity, etc., thereby improving its zinc storage capacity.

[0004] By searching domestic and foreign public literature, we found that there are basically no reports on the preparation of manganese oxide polyhedron materials and their use in aqueous zinc ion batteries. Therefore, it is of great significance to develop new technologies for the preparation of manganese oxide polyhedron materials for aqueous zinc ion batteries. Summary of the invention

[0005] In view of the shortcomings of existing manganese oxide electrode materials in the application of zinc ion batteries, the purpose of the present invention is to provide a method for preparing manganese oxide polyhedron materials for aqueous zinc ion batteries by improving the preparation technology of manganese oxide materials.

[0006] In order to achieve the purpose of the present invention, the inventors combined their own scientific research experience in energy storage materials for many years, and conducted a large number of experimental studies and continuous improvements. Finally, the surface activity of acetic acid and its weak acidity, as well as a special annealing process, increased the exposed crystal surface of manganese oxide materials, thereby preparing a novel manganese oxide polyhedral structure material. The unique morphology and crystal surface structure of the material can be used in Zn 2+It plays an important role in the energy storage process, thereby improving the zinc storage capacity of manganese oxide.

[0007] The technical purpose of the present invention is achieved in this way: a method for preparing a manganese oxide polyhedron material for an aqueous zinc ion battery, which is specifically implemented by the following steps: dissolving a divalent manganese salt and a chlorate in an acetic acid aqueous solution, subjecting the obtained mixed solution to a hydrothermal treatment at a temperature of 170 to 190° C. for 6 to 10 hours, washing and vacuum drying the obtained precipitate after the hydrothermal treatment, and then annealing at 300 to 400° C. for 1 to 2 hours to obtain the manganese oxide polyhedron material; during the annealing process, when the temperature in the heating and cooling stages is lower than 80° C., the atmosphere is nitrogen; and the atmosphere in other stages is a mixed gas of argon and hydrogen, and the hydrogen content is 7.8 to 8.3%.

[0008] Further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the molar ratio of divalent manganese salt to chlorate is (1.0-2.0): (6.0-7.0).

[0009] Still further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the molar ratio of divalent manganese salt to chlorate is 1.8:6.7.

[0010] Further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the concentration of the acetic acid aqueous solution is 0.8 to 1.2 mol / L.

[0011] Further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the temperature of the hydrothermal treatment is 180°C and the time is 8 hours. Under this temperature and time parameters, the prepared manganese oxide polyhedron material has higher zinc storage capacity and rate performance.

[0012] Further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the annealing treatment is carried out in a tubular furnace with a heating rate of 3-5°C / min.

[0013] Further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the gas flow rate of the gas during annealing treatment is 80-100 mL / min.

[0014] Still further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the divalent manganese salt is selected from one or more of the following: manganese nitrate hexahydrate, manganese sulfate monohydrate, manganese acetate tetrahydrate, and manganese chloride tetrahydrate.

[0015] Still further preferably, in the method for preparing manganese oxide polyhedron material for aqueous zinc ion battery as described above, the chlorate is selected from one or a mixture of two of the following: sodium chlorate and potassium chlorate.

[0016] In addition, the present invention also provides manganese oxide polyhedron material for aqueous zinc ion batteries prepared by the above method.

[0017] Compared with the prior art, the present invention has the following advantages and progress:

[0018] The present invention increases the exposed crystal surface of manganese oxide material through the surface activity of acetic acid and special annealing process and parameters. When used as positive electrode material of aqueous zinc ion battery, abundant manganese defects will be generated during zinc storage process, which promotes Zn 2+ The deintercalation of manganese oxide can improve the zinc storage capacity and rate performance of manganese oxide. In addition, the present invention has the advantages of easy availability of raw materials and obvious performance improvement, and is an effective preparation method for positive electrode materials of aqueous zinc ion batteries, with high practical application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is the XRD pattern of the manganese oxide material prepared in Example 1 of the present invention;

[0020] Figure 2 is a SEM image of the manganous oxide material prepared in Example 1 of the present invention;

[0021] Figure 3 is the CV curve of the manganese oxide material prepared in Example 1 of the present invention;

[0022] Figure 4 is the GCD curve of the manganese oxide material prepared in Example 1 of the present invention;

[0023] Figure 5 is a cyclic stability diagram of the manganese oxide material prepared in Example 1 of the present invention;

[0024] Figure 6 is a SEM image of the manganese oxide material prepared in Example 2 of the present invention;

[0025] Figure 7 is a SEM image of the manganese oxide material prepared in Example 3 of the present invention;

[0026] Figure 8 3 is a SEM image of the manganese oxide material prepared in Example 4 of the present invention.

[0027] Fig. 9 It is a SEM picture of the manganous oxide material prepared in Comparative Example 1 of the present invention.

[0028] Fig.10It is a SEM picture of the manganese oxide material prepared in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0029] The present invention proposes a surfactant-assisted special atmosphere treatment technology to construct a polyhedral manganese oxide material, which is used as a positive electrode material for zinc ion batteries. Its unique morphology and crystal surface structure are beneficial to Zn 2+ The rapid deintercalation in the material significantly improves the zinc storage performance of the manganese oxide material. The preparation method of the present invention is described in detail below in conjunction with the accompanying drawings and specific examples, but the protection scope of the present invention is not limited to the following examples.

[0030] It should be noted that the preparation of the working electrode and the electrochemical test method are as follows: the working electrode is prepared using the sample obtained in the embodiment of the present invention as the active material. Active material: SuperP: PVDF is mixed in a mass ratio of 7:2:1, and N-methylpyrrolidone is used as a solvent. The paste is ground into a slurry in a mortar, and the slurry is evenly coated on a titanium foil (99.9%, 10μm), and dried in a vacuum drying oven at 60°C for 12h. The loading amount of the active material is about 1.8mg / cm 2 The prepared working electrode was used as the positive electrode, the metal zinc foil was used as the negative electrode, and the glass fiber membrane was used as the separator. 4 and 0.1MMnSO 4 The mixed aqueous solution was used as electrolyte to form a CR2032 coin battery, and its electrochemical properties were tested on a Princeton ParSTATMC2000A electrochemical workstation.

[0031] Embodiment 1:

[0032] Dilute 17 mol / L glacial acetic acid with water to prepare 35 mL of 1.0 mol / L acetic acid solution. Weigh 1.8 mmol of hexahydrate manganese nitrate and 6.7 mmol of sodium chlorate and add them to the above solution, stirring at room temperature for 30 min. Transfer the obtained clear solution to a 50 mL polytetrafluoroethylene-lined reactor and hydrothermally heat at 180 ° C for 8 h. After the hydrothermal precipitate is filtered under reduced pressure, washed with deionized water and ethanol, it is vacuum dried at 60 ° C for 12 h. The obtained dry powder sample is placed in a porcelain boat and placed in a tubular furnace for annealing. The heating rate of the tubular furnace is 3 ° C / min, and the annealing treatment is performed at 400 ° C for 1 h. When the temperature in the heating and cooling stages is lower than 80 ° C, the atmosphere in the furnace is nitrogen, and the atmosphere in the furnace in other stages is a mixture of argon and hydrogen with a hydrogen content of 8%, and the gas flow rate is 100 mL / min. After the reaction is completed, the product is collected to obtain the electrode material of the present invention. The obtained electrode material was subjected to XRD test analysis to characterize its phase. The results are as follows: Figure 1 The product was tested by SEM to observe its surface morphology. The results are as follows Figure 2 As shown in the figure, it can be seen that the surface is rough and the polyhedron morphology indicates that this method has successfully prepared manganese oxide polyhedron materials. The CV curves observed a pair of reduction peaks and oxidation peaks at 1.58V and 1.19V, respectively, corresponding to Zn 2+ The insertion and extraction peaks in the manganese oxide cathode material correspond to H + Embedment and extraction in materials, the results are as follows Figure 3 The GCD curves of the material at different current densities show two discharge platforms, corresponding to H + and Zn 2+ The results of deintercalation in manganese oxide materials are as follows Figure 4 As shown, it is consistent with the CV test results. At a current density of 0.1A / g, the discharge specific capacity is 204mAh / g at the tenth cycle of charge and discharge. At a current density of 2.0A / g, it continuously charges and discharges for 1000 cycles, with a high capacity retention rate. The results are as follows Figure 5 As shown, it can be used as a positive electrode material for zinc ion batteries.

[0033] Example 2

[0034] Dilute 17 mol / L glacial acetic acid with water to prepare 35 mL of 1.0 mol / L acetic acid solution. Weigh 1.8 mmol of manganese nitrate hexahydrate and 6.5 mmol of sodium chlorate and add them to the above solution, stirring at room temperature for 30 min. Transfer the resulting clear solution to a 50 mL polytetrafluoroethylene-lined reactor and hydroheat at 180°C for 8 h. The precipitate obtained by hydrothermal treatment was filtered under reduced pressure, washed with deionized water and ethanol, and then vacuum dried at 60°C for 12 h. The resulting dry powder sample was placed in a porcelain boat and placed in a tubular furnace for annealing. The heating rate of the tubular furnace was 3°C / min, and the annealing treatment was performed at 350°C for 2 h. When the temperature in the heating and cooling stages was lower than 80°C, the atmosphere in the furnace was nitrogen, and in other stages the atmosphere in the furnace was a mixture of argon and hydrogen with a hydrogen content of 8%, and the gas flow rate was 100 mL / min. After the reaction is completed, collect the product to obtain the electrode material of the present invention. The SEM photograph is of a polyhedral material, and the results are as follows Figure 6 As shown. At a current density of 0.1A / g, the discharge specific capacity is 223mAh / g during the tenth cycle of charge and discharge.

[0035] Example 3

[0036] Dilute 17 mol / L glacial acetic acid with water to prepare 35 mL of 1.0 mol / L acetic acid solution. Weigh 1.8 mmol of manganese nitrate hexahydrate and 6.8 mmol of potassium chlorate and add them to the above solution, stirring at room temperature for 30 min. Transfer the obtained clear solution to a 50 mL polytetrafluoroethylene-lined reactor and hydroheat at 180°C for 8 h. The precipitate obtained by hydrothermal treatment was filtered under reduced pressure, washed with deionized water and ethanol, and then vacuum dried at 60°C for 12 h. The obtained dry powder sample was placed in a porcelain boat and placed in a tubular furnace for annealing. The heating rate of the tubular furnace was 5°C / min, and the annealing treatment was performed at 400°C for 1 h. When the temperature in the heating and cooling stages was lower than 80°C, the atmosphere in the furnace was nitrogen, and the atmosphere in the other stages was a mixture of argon and hydrogen with a hydrogen content of 8%, and the gas flow rate was 80 mL / min. After the reaction is completed, collect the product to obtain the electrode material of the present invention. The SEM photo shows a polyhedral material with a slightly increased size. The results are as follows Figure 7 As shown. At a current density of 0.1A / g, the discharge specific capacity is 191mAh / g during the tenth cycle of charge and discharge.

[0037] Example 4

[0038] Dilute glacial acetic acid with a concentration of 17 mol / L with water to prepare 35 mL of 1.0 mol / L acetic acid solution. Weigh 1.8 mmol of hexahydrate manganese nitrate and 6.8 mmol of potassium chlorate and add them to the above solution, stirring at room temperature for 30 min. Transfer the obtained clear solution to a 50 mL polytetrafluoroethylene-lined reactor and hydrothermally heat at 180 ° C for 8 h. After the hydrothermal precipitate is filtered under reduced pressure, washed with deionized water and ethanol, it is vacuum dried at 60 ° C for 12 h. The obtained dry powder sample is placed in a porcelain boat and placed in a tubular furnace for annealing. The heating rate of the tubular furnace is 5 ° C / min, and the annealing treatment is performed at 350 ° C for 2 h. When the temperature in the heating and cooling stages is lower than 80 ° C, the atmosphere in the furnace is nitrogen, and the atmosphere in the furnace in other stages is a mixture of argon and hydrogen with a hydrogen content of 8%, and the gas flow rate is 100 mL / min. After the reaction is completed, the product is collected to obtain the electrode material of the present invention. The SEM photos are of polyhedral materials with slight changes on the surface of the polyhedron. Figure 8 As shown. At a current density of 0.1A / g, the discharge specific capacity is 257mAh / g during the tenth cycle of charge and discharge.

[0039] Comparative Example 1 (deionized water was used as the reaction solvent instead of acetic acid)

[0040] Weigh 1.8 mmol of manganese nitrate hexahydrate and 6.7 mmol of sodium chlorate and add them to 35 mL of deionized water, and stir at room temperature for 30 minutes. Transfer the obtained clear solution to a 50 mL polytetrafluoroethylene-lined reactor and hydroheat it at 180°C for 8 hours. The precipitate obtained by hydrothermal treatment was filtered under reduced pressure, washed with deionized water and ethanol, and then vacuum dried at 60°C for 12 hours. The obtained dry powder sample was placed in a porcelain boat and placed in a tubular furnace for annealing. The heating rate of the tubular furnace was 3°C / min, and the annealing treatment was performed at 400°C for 1 hour. When the temperature was lower than 80°C during the heating and cooling stages, the atmosphere in the furnace was nitrogen. In other stages, the atmosphere in the furnace was a mixture of argon and hydrogen with a hydrogen content of 8%, and the gas flow rate was 80 mL / min. After the reaction is completed, collect the product to obtain the electrode material. The SEM photograph shows a coil-like morphology, and the results are as follows Fig. 9 As shown. At a current density of 0.1A / g, the discharge specific capacity is 113mAh / g during the tenth cycle of charge and discharge.

[0041] Comparative Example 2 (Furnace atmosphere is always nitrogen)

[0042] Weigh 1.8 mmol of manganese nitrate hexahydrate and 6.7 mmol of sodium chlorate, add to 35 mL of deionized water, and stir at room temperature for 30 min. Transfer the resulting clear solution to a 50 mL polytetrafluoroethylene-lined reactor and hydroheat at 180 °C for 8 h. The precipitate obtained by hydrothermal treatment was filtered under reduced pressure, washed with deionized water, and washed with ethanol, and then vacuum dried at 60 °C for 12 h. The obtained dry powder sample was placed in a porcelain boat and placed in a tubular furnace for annealing. The heating rate of the tubular furnace was 3 °C / min, and annealing was performed at 400 °C for 1 h in a continuous nitrogen atmosphere. The gas flow rate was 80 mL / min. After the reaction is completed, collect the product to obtain the electrode material. SEM photos show that the prepared material has an uneven large block morphology. The results are as follows Fig.10 As shown. At a current density of 0.1A / g, the discharge specific capacity is 142mAh / g during the tenth cycle of charge and discharge.

[0043] By studying the SEM photos and electrochemical properties of the materials prepared in Examples 1 to 4 and Comparative Examples 1 to 2, it can be seen that acetic acid and argon-hydrogen mixed gas with a hydrogen content of 8% play an important role in regulating the morphology of manganese oxide. In addition, the zinc storage capacity of the manganese oxide polyhedral material prepared by the present invention is much higher than that of the material with a coil-like morphology and an uneven large block morphology, which shows that the polyhedral manganese oxide positive electrode material can significantly improve the zinc storage capacity due to its special structural characteristics, and thus can be used as a positive electrode material for aqueous zinc ion batteries.

Claims

1. A method for preparing manganese oxide polyhedron material for aqueous zinc ion batteries, It is characterized in that The method comprises the following steps: dissolving a divalent manganese salt and a chlorate in an acetic acid aqueous solution, subjecting the obtained mixed solution to hydrothermal treatment at a temperature of 170-190 DEG C for 6-10 hours, washing and vacuum drying the obtained precipitate after the hydrothermal treatment, and then annealing at 300-400 DEG C for 1-2 hours to obtain a manganese oxide polyhedron material; during the annealing process, when the temperature in the heating and cooling stages is lower than 80 DEG C, the atmosphere is nitrogen; and the atmosphere in other stages is a mixed gas of argon and hydrogen, and the hydrogen content is 7.8-8.3%.

2. The method for preparing the manganese oxide polyhedron material for aqueous zinc ion battery according to claim 1, It is characterized in that The molar ratio of the divalent manganese salt to the chlorate is (1.0-2.0):(6.0-7.0).

3. The method for preparing the manganese oxide polyhedron material for aqueous zinc ion battery according to claim 2, It is characterized in that The molar ratio of the divalent manganese salt to the chlorate is 1.8:6.

7.

4. The method for preparing the manganese oxide polyhedron material for aqueous zinc ion battery according to claim 1, It is characterized in that The concentration of the acetic acid aqueous solution is 0.8-1.2 mol / L.

5. The method for preparing the manganese oxide polyhedron material for aqueous zinc ion battery according to claim 1, It is characterized in that The temperature of the hydrothermal treatment is 180° C. and the time is 8 hours.

6. The method for preparing the manganese oxide polyhedron material for aqueous zinc ion battery according to claim 1, It is characterized in that The annealing treatment is carried out in a tubular furnace, and the heating rate of the tubular furnace is 3-5° C. / min.

7. The method for preparing the manganese oxide polyhedron material for aqueous zinc ion batteries according to claim 6, It is characterized in that The gas flow rate of the gas during the annealing treatment is 80-100 mL / min.

8. A method for preparing the manganese oxide polyhedron material for aqueous zinc ion batteries according to any one of claims 1 to 7, It is characterized in that The divalent manganese salt is selected from one or more of the following: manganese nitrate hexahydrate, manganese sulfate monohydrate, manganese acetate tetrahydrate, and manganese chloride tetrahydrate.

9. A method for preparing the manganese oxide polyhedron material for aqueous zinc ion batteries according to any one of claims 1 to 7, It is characterized in that The chlorate is selected from one or a mixture of two of the following: sodium chlorate and potassium chlorate.

10. A manganese oxide polyhedron material for aqueous zinc ion batteries prepared according to the method according to any one of claims 1 to 7.

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