Magnesium defect type magnesium-manganese spinel nano material as well as preparation method and application thereof
By constructing magnesium defect structures in magnesium manganese spinel nanomaterials, the migration rate and stability issues of magnesium manganese spinel cathode materials were solved, achieving high-capacity and long-cycle stable performance of aqueous magnesium-ion batteries, thus promoting their industrialization.
Patent Information
- Application Number
- CN202511888813.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-15
- Publication Date
- 2026-02-24
AI Technical Summary
In aqueous magnesium-ion batteries, the slow ion migration rate and insufficient structural stability of the magnesium-manganese spinel cathode material result in poor rate performance and cycle stability, making it difficult to meet high power requirements and long-term reliable operation.
Magnesium-rich vacancy defect structures were constructed in magnesium-manganese spinel nanomaterials by controlled acid etching, forming magnesium-defect-type magnesium-manganese spinel nanomaterials, which improved ion migration rate and enhanced structural stability.
High capacity, high rate performance and long cycle stability of magnesium manganese spinel nanomaterials were achieved. The discharge specific capacity exceeded 300 mAh/g at 100 mA/g, and the capacity was maintained at more than 60% after 1000 cycles at a current density of 1 A/g, which significantly improved the electrochemical performance of aqueous magnesium-ion batteries.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of magnesium battery technology, specifically relating to a magnesium defect-type magnesium manganese spinel nanomaterial, its preparation method, and its application. Background Technology
[0002] Magnesium-ion batteries, as one of the core candidates for next-generation green energy storage technology, have become an important direction for replacing traditional lithium-ion batteries due to the natural advantages of magnesium resources, such as high abundance in the Earth's crust (approximately 2.3%), low cost, and the high theoretical capacity of metallic magnesium anodes (3833 mAh / cm3) and resistance to dendrite growth. Among them, aqueous magnesium-ion batteries, by using aqueous solutions as electrolytes, fundamentally solve the safety hazards of flammability and explosion of organic electrolytes, possessing unparalleled intrinsic safety. At the same time, aqueous electrolytes also have the characteristics of high ionic conductivity (typically 2-3 orders of magnitude higher than organic electrolytes), low preparation cost, and relaxed requirements for the production environment (no strict anhydrous and oxygen-free conditions are required), which greatly simplifies the battery manufacturing process and reduces equipment investment, demonstrating extremely strong prospects for industrial application.
[0003] However, the development of aqueous magnesium-ion batteries still faces a key bottleneck: divalent magnesium ions (Mg... 2+ The strong Coulomb interaction between the metal and the cathode material lattice results in slow diffusion kinetics in the solid phase, severely limiting the rate performance and capacity of the battery. Among many cathode candidates, magnesium manganese spinel (MgMn2O4), although possessing a high operating voltage (approximately 1.5V vs Mg...),... 2+ While possessing advantages such as high Mg content and high theoretical capacity (approximately 110 mAh / g), its practical application is still limited by two core issues: one is Mg content. 2+ The low migration rate in the spinel lattice makes it unsuitable for high power requirements; secondly, structural degradation phenomena such as manganese ion dissolution and lattice distortion are prone to occur during cycling, leading to rapid capacity decay, poor cycling stability, and difficulty in achieving long-term reliable operation.
[0004] To address the issues of slow ion migration rate and insufficient structural stability in magnesium manganese spinel (MgMn2O4) cathode materials, existing technologies lack effective strategies to simultaneously improve both ionic conductivity and structural stability. Therefore, developing a modification method to overcome these bottlenecks and enhance the actual electrochemical performance of MgMn2O4 is of great significance for promoting the industrialization of aqueous magnesium-ion batteries. Summary of the Invention
[0005] To address the aforementioned issues, this invention provides a method for constructing magnesium-rich vacancy defect structures in magnesium manganese spinel (MgMn2O4) nanomaterials through controlled acid etching to obtain magnesium-defect-type magnesium manganese spinel nanomaterials. This simultaneously achieves a synergistic improvement in the high capacity, high rate capability, and long cycle stability of the magnesium manganese spinel nanomaterials, providing an effective solution for advancing the practical application of aqueous magnesium-ion batteries.
[0006] To achieve the above objectives, the present invention can adopt the following technical solutions: This invention provides a magnesium-defect-type magnesium manganese spinel nanomaterial with the chemical formula Mg. x Mn2O4, where 0.1≤x≤0.8.
[0007] Preferably, in the above-mentioned magnesium-defect type magnesium manganese spinel nanomaterial, 0.3≤x≤0.42.
[0008] More preferably, in the above-mentioned magnesium-defect-type magnesium manganese spinel nanomaterial, x is 0.36.
[0009] Another aspect of the present invention provides a method for preparing the above-mentioned magnesium defect type magnesium manganese spinel nanomaterial. The preparation method includes: (1) mixing the initial magnesium manganese spinel nanomaterial with an acid solution to react and separating to obtain a solid product; (2) washing, drying and grinding the solid product in sequence to obtain the magnesium defect type magnesium manganese spinel nanomaterial.
[0010] Preferably, in the above preparation method, the acid solution is selected from hydrochloric acid solution.
[0011] More preferably, the reaction includes: dispersing the initial magnesium manganese spinel nanomaterial in an acid solution for reaction, wherein the solid content of the initial magnesium manganese spinel nanomaterial is 10 mg / mL to 100 mg / mL, and the concentration of the acid solution is 0.1 mol / L to 1 mol / L.
[0012] Preferably, the above preparation method satisfies one or more of the following conditions: (i) the reaction includes: continuous stirring at 25℃ to 35℃ for 1h to 6h; (ii) the drying includes: drying temperature of 60℃ to 100℃ and drying time of 8h to 16h.
[0013] In another aspect, the present invention provides an aqueous magnesium-ion battery cathode, comprising the aforementioned magnesium-defect magnesium-manganese spinel nanomaterial or magnesium-defect magnesium-manganese spinel nanomaterial prepared by the aforementioned preparation method, wherein the magnesium-defect magnesium-manganese spinel nanomaterial serves as the cathode active material.
[0014] In another aspect, the present invention provides an aqueous magnesium-ion battery, which includes the above-described aqueous magnesium-ion battery positive electrode.
[0015] In another aspect, the present invention provides the application of the above-mentioned magnesium defect-type magnesium manganese spinel nanomaterial or the magnesium defect-type magnesium manganese spinel nanomaterial prepared by the above-mentioned preparation method as a positive electrode active material for aqueous magnesium-ion batteries.
[0016] The beneficial effects of this invention include at least the following: the magnesium defect-type magnesium manganese spinel nanomaterial provided by this invention exhibits excellent electrochemical performance. When used as an electrode material in an aqueous magnesium-ion battery, it achieves a discharge specific capacity exceeding 300 mAh / g in a 0.5 M Mg(NO3)2 aqueous electrolyte at a current density of 100 mA / g; when the current density is 1 A / g, the initial discharge specific capacity reaches as high as 180 mAh / g, and after 1000 cycles at a current density of 1 A / g, its discharge specific capacity can still be maintained at 110 mAh / g, with a capacity retention rate exceeding 60%; it also exhibits excellent cycle stability. Attached Figure Description
[0017] Figure 1 X-ray diffraction patterns of magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 1 and magnesium manganese spinel nanomaterials prepared in Comparative Example 1; Figure 2 Scanning electron microscope images of magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 1 and magnesium manganese spinel nanomaterials prepared in Comparative Example 1; Figure 3 The cycle life curves of the battery assembled based on the magnesium defect-type magnesium manganese spinel nanomaterial prepared in Example 1 and the magnesium manganese spinel nanomaterial prepared in Comparative Example 1 are shown at a current density of 100 mA / g. Figure 4 Cycle life curves at 1 A / g current density are shown for the magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 1 and the batteries assembled from the magnesium manganese spinel nanomaterials prepared in Comparative Example 1. Detailed Implementation
[0018] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.
[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.
[0020] In a first aspect, embodiments of the present invention provide a magnesium-defect-type magnesium-manganese spinel nanomaterial, the chemical formula of which is Mg x Mn2O4, where 0.1≤x≤0.8.
[0021] It should be noted that magnesium-defect-type MgMn2O4 spinel nanomaterials were obtained by constructing magnesium-rich vacancy defect structures in MgMn2O4 nanomaterials through controlled acid etching. This simultaneously achieved a synergistic improvement in the high capacity, high rate capability, and long cycle stability of the MgMn2O4 nanomaterials, providing an effective solution for advancing the practical application of aqueous magnesium-ion batteries. Specifically, the magnesium defects introduced into this magnesium-defect-type MgMn2O4 nanomaterials effectively reduce the diffusion barrier of magnesium ions and widen the ion migration channels, thereby improving the rate performance and reversible capacity of the material. At the same time, magnesium vacancies help buffer lattice stress during charge and discharge, suppress structural distortion caused by the Jahn-Teller effect, and thus enhance the stability of the crystal framework, reduce manganese dissolution, and extend cycle life. Furthermore, the magnesium-defect-type MgMn2O4 nanomaterials of this invention have the same microstructure as the initial MgMn2O4 nanomaterials (MgMn2O4 nanomaterials without magnesium defects), both possessing a tetragonal spinel crystal structure.
[0022] In some specific examples, in the above-mentioned magnesium-defective magnesium manganese spinel nanomaterials, 0.3 ≤ x ≤ 0.42.
[0023] It should be noted that the value of x in this invention can be further ranged from 0.3 to 0.42 (i.e., the magnesium-manganese molar ratio is (0.3-0.42):2), such as 0.31, 0.32, 0.33, 0.34, 0.35, 0.36, 0.37, 0.38, 0.39, 0.40, or 0.41. Magnesium-defect-type magnesium-manganese spinel nanomaterials within this value range exhibit better electrochemical performance than those with other values.
[0024] In some specific examples, the value of x is 0.36 in the above-mentioned magnesium-defective magnesium-manganese spinel nanomaterials.
[0025] It should be noted that the value of x in this invention can be further taken as 0.36, that is, the electrochemical performance of magnesium defect type magnesium manganese spinel nanomaterials with a magnesium manganese molar ratio of 0.36:2 is better than other values.
[0026] In a second aspect, embodiments of the present invention provide a method for preparing the above-mentioned magnesium defect type magnesium manganese spinel nanomaterial. The preparation method includes: (1) mixing the initial magnesium manganese spinel nanomaterial with an acid solution to react and separating to obtain a solid product; (2) washing, drying and grinding the solid product in sequence to obtain the magnesium defect type magnesium manganese spinel nanomaterial.
[0027] It should be noted that in this invention, by controlling the acid concentration (especially hydrochloric acid) and the time for acid etching of the material, an appropriate amount of defects are introduced into the spinel structure, thereby obtaining acid-etched magnesium manganese spinel material. The raw material cost is low, the operation process is simple, and it can be used for large-scale industrial production.
[0028] In some specific examples, the acid solution in the above preparation method is selected from hydrochloric acid solution.
[0029] In some specific examples, the reaction includes dispersing initial magnesium manganese spinel nanomaterials in a hydrochloric acid solution for reaction, wherein the solid content of the initial magnesium manganese spinel nanomaterials is 10 mg / mL to 100 mg / mL, and the concentration of the acid solution is 0.1 mol / L to 1 mol / L.
[0030] It should be noted that when the acid solution is hydrochloric acid, the initial solid content of the magnesium manganese spinel nanomaterial can be 10 mg / mL to 100 mg / mL, such as 20 mg / mL, 30 mg / mL, 40 mg / mL, 50 mg / mL, 60 mg / mL, 70 mg / mL, 80 mg / mL, or 90 mg / mL; the concentration of the acid solution is 0.1 mol / L to 1 mol / L, such as 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, or 0.9 mol / L.
[0031] In some specific examples, the above preparation method satisfies one or more of the following conditions: (i) the reaction includes: continuous stirring at 25℃ to 35℃ for 1h to 6h; (ii) the drying includes: drying temperature of 60℃ to 100℃ and drying time of 8h to 16h.
[0032] It should be noted that the etching reaction in this invention can be carried out with stirring at room temperature, and the reaction time can be 1h–6h, such as 2h, 3h, 4h, or 5h; the drying temperature can be 60℃–100℃, such as 70℃, 80℃, or 90℃, and the drying time at this temperature can be 8h–16h, such as 9h, 10h, 11h, 12h, 13h, 14h, or 15h. Furthermore, the drying method is known in the art, such as using a forced-air drying oven or a vacuum drying oven.
[0033] Thirdly, embodiments of the present invention provide an aqueous magnesium-ion battery cathode, which includes the aforementioned magnesium-defect magnesium-manganese spinel nanomaterial or the magnesium-defect magnesium-manganese spinel nanomaterial prepared by the aforementioned preparation method, wherein the magnesium-defect magnesium-manganese spinel nanomaterial serves as the cathode active material.
[0034] It should be noted that the magnesium-defect-type magnesium-manganese spinel nanomaterials of this invention exhibit excellent electrochemical performance. When used as an electrode material in an aqueous magnesium-ion battery, in a 0.5M Mg(NO3)2 aqueous electrolyte, the discharge specific capacity exceeds 300 mAh / g at a current density of 100 mA / g; at a current density of 1 A / g, the initial discharge specific capacity reaches as high as 180 mAh / g, and after 1000 cycles at a current density of 1 A / g, its discharge specific capacity still maintains 110 mAh / g, with a capacity retention rate exceeding 60%; demonstrating excellent cycle stability. It can be combined with other reagents (such as acetylene black or PVDF binder) to prepare an aqueous magnesium-ion battery cathode, and the shape of the cathode can be selected as needed, such as rod-shaped or sheet-shaped.
[0035] Fourthly, embodiments of the present invention provide an aqueous magnesium-ion battery, which includes the above-described aqueous magnesium-ion battery positive electrode.
[0036] It should be noted that the positive electrode prepared based on the magnesium defect type magnesium manganese spinel nanomaterial of the present invention can be assembled into an aqueous magnesium-ion battery. The negative electrode, electrolyte and battery separator of the aqueous magnesium battery are all known in the art. For example, a 0.5 M Mg(NO3)2 aqueous solution is used as the electrolyte, activated carbon is used as the negative electrode and glass fiber membrane is used as the separator.
[0037] Fifthly, embodiments of the present invention provide an application of the above-described magnesium defect-type magnesium manganese spinel nanomaterial or the magnesium defect-type magnesium manganese spinel nanomaterial prepared by the above-described preparation method as a positive electrode active material for aqueous magnesium-ion batteries.
[0038] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.
[0039] Preparation Examples Example 1 (1) Preparation of initial magnesium manganese spinel (MgMn2O4) nanomaterials (1-1) Preparation of metal salt solution: Dissolve 2.5 mmol magnesium acetate tetrahydrate and 5.0 mmol manganese acetate tetrahydrate in 37.5 mL anhydrous ethanol and stir until completely dissolved to obtain solution A; (1-2) Preparation of precipitant solution: Dissolve 7.5 mmol of oxalic acid dihydrate in 7.5 mL of anhydrous ethanol and stir until completely dissolved to obtain solution B; (1-3) Coprecipitation reaction: Under continuous stirring, solution B is slowly added dropwise to solution A at a rate of 1 mL / min, and stirring is continued for 10 min after the addition is completed; (1-4) Precursor drying: The obtained suspension was placed in a 60℃ forced-air drying oven and dried for 24 hours to obtain the precursor solid; (1-5) High-temperature calcination: After grinding the precursor, it was heated to 650°C in a muffle furnace at a heating rate of 5°C / min and held for 3 hours. Then it was cooled to room temperature with the furnace to obtain the initial magnesium manganese spinel nanomaterial.
[0040] (2) Preparation of magnesium defect-type magnesium manganese spinel nanomaterials (2-1) Weigh 300 mg of the magnesium manganese spinel nanomaterial prepared in step (1) and add it to 10 mL of 0.3 mol / L hydrochloric acid solution. Stir at 30 °C for 2 h to obtain the reaction mixture. (2-2) The reaction mixture obtained in step (2-1) was centrifuged at 10,000 rpm for 2 minutes. The solid product was collected and washed with deionized water 3 times and ethanol once. (2-3) The product obtained in step (2-2) was transferred to a forced-air drying oven and dried at 80°C for 16 hours. After grinding in a mortar, magnesium defect type magnesium manganese spinel nanomaterials were obtained.
[0041] Example 2 Example 2 is largely the same as Example 1, except that the concentration of hydrochloric acid solution in step (2-1) is different, while the rest is the same as in Example 1; wherein, the concentration of hydrochloric acid solution in step (2-1) of Example 2 is 0.2 mol / L.
[0042] Example 3 Example 3 is largely the same as Example 1, except that the concentration of hydrochloric acid solution in step (2-1) is different, while the rest is the same as Example 1; wherein, the concentration of hydrochloric acid solution in step (2-1) of Example 2 is 0.5 mol / L.
[0043] Example 4 Example 4 is largely the same as Example 1, except that the stirring time at 30°C in step (2-2) is different, while the rest is the same as in Example 1; wherein, in Example 4, the stirring time at 30°C in step (2-2) is 4 hours.
[0044] Comparative Example 1 Comparative Example 1 is an initial magnesium manganese spinel nanomaterial, which is prepared by the same method as step (1) of Example 1.
[0045] Characterization test The X-ray diffraction (XRD) pattern of the magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 1 is as follows: Figure 1 As shown, the results indicate that the magnesium-defect-type magnesium-manganese spinel nanomaterial possesses a tetragonal spinel crystal structure, identical to the initial magnesium-manganese spinel nanomaterial (Comparative Example 1). Furthermore, the scanning electron microscope (SEM) measurements of the magnesium-defect-type magnesium-manganese spinel nanomaterial prepared in Example 1 are as follows: Figure 2 As shown, the results indicate that the microstructure of this magnesium-defect-type magnesium-manganese spinel nanomaterial is a honeycomb-like porous structure formed by the random accumulation of spinel particles, which is similar to the microstructure of the magnesium-manganese spinel nanomaterial before acid treatment. Furthermore, ICP testing results show that the magnesium-manganese molar ratio of the magnesium-defect-type magnesium-manganese spinel nanomaterial is 0.36:2, and the magnesium ion content is significantly reduced, confirming the formation of magnesium defects.
[0046] The ICP test (inductively coupled plasma optical emission spectrometry (ICP-OES) test, instrument model: Agilent 5800 (OES), USA, hereinafter the same) results of the magnesium defect type magnesium manganese spinel nanomaterial prepared in Example 2 showed that its magnesium manganese molar ratio was 0.42:2.
[0047] The ICP test results of the magnesium defect-type magnesium manganese spinel nanomaterial prepared in Example 3 showed that its magnesium-manganese molar ratio was 0.3:2.
[0048] The ICP test results of the magnesium defect-type magnesium manganese spinel nanomaterial prepared in Example 4 showed that its magnesium-manganese molar ratio was 0.32:2.
[0049] The X-ray diffraction (XRD) pattern of the initial magnesium-manganese spinel nanomaterial in Comparative Example 1 is as follows: Figure 1 As shown, the results indicate that the material also possesses a tetragonal spinel crystal structure. Furthermore, the ICP test results of the initial magnesium-manganese spinel material (MgMn2O4) in Comparative Example 1 show that its magnesium-manganese molar ratio is 1:2.02, which is essentially consistent with the theoretical magnesium-manganese ratio (1:2) of MgMn2O4.
[0050] Performance testing The magnesium-defect-type magnesium-manganese spinel nanomaterials prepared in the examples and the initial magnesium-manganese spinel nanomaterials prepared in the comparative examples were used as positive electrode active materials for aqueous magnesium-ion batteries to assemble coin cells and test their electrochemical performance. Details are as follows: Preparation of positive electrode: Magnesium defect-type magnesium manganese spinel nanomaterials or initial magnesium manganese spinel nanomaterials, acetylene black and PVDF binder are dispersed in NMP (methylpyrrolidone) at a mass ratio of 7:2:1 and thoroughly ground to obtain a viscous slurry; then the slurry is uniformly coated onto a stainless steel current collector with a 200μm thick scraper, dried at 60℃ for 6h, and then cut into positive electrode discs with a diameter of 10mm using a cutting machine; Button cell assembly: A button cell is assembled using a 0.5M Mg(NO3)2 aqueous solution as the electrolyte, activated carbon as the negative electrode, a glass fiber membrane as the separator, and CR 2032 stainless steel as the battery casing.
[0051] The magnesium defect-type magnesium-manganese spinel nanomaterials prepared in Example 1 were assembled into coin cells according to the above method, and their electrochemical performance was tested. The test results showed that at a current density of 100 mA / g, the initial discharge specific capacity could reach 300 mAh / g (see...). Figure 3 When the current density is 1 A / g, the initial discharge specific capacity is as high as 180 mAh / g. After 1000 cycles, its discharge specific capacity can still be maintained at 110 mAh / g, with a capacity retention rate of 61.1% (see...). Figure 4 ).
[0052] The magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 2 were assembled into coin cells according to the above method and their electrochemical performance was tested. The test results showed that the discharge specific capacity could reach 280 mAh / g at a current density of 100 mA / g and 160 mAh / g at a current density of 1 A / g.
[0053] The magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 3 were assembled into coin cells according to the above method and their electrochemical performance was tested. The test results showed that the discharge specific capacity could reach 270 mAh / g at a current density of 100 mA / g and 150 mAh / g at a current density of 1 A / g.
[0054] The magnesium defect-type magnesium manganese spinel nanomaterials prepared in Example 4 were assembled into coin cells according to the above method and their electrochemical performance was tested. The test results showed that the discharge specific capacity could reach 280 mAh / g at a current density of 100 mA / g and 160 mAh / g at a current density of 1 A / g.
[0055] The initial magnesium-manganese spinel nanomaterials prepared in Comparative Example 1 were assembled into coin cells using the method described above, and their electrochemical performance was tested. The test results showed that at a current density of 100 mA / g, the initial discharge specific capacity was only 50 mAh / g, and the maximum discharge specific capacity did not exceed 200 mAh / g (see...). Figure 3 When the current density is 1 A / g, after 1000 cycles, its discharge specific capacity is only 70 mAh / g (see...). Figure 4 ).
[0056] 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 it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A magnesium-defect-type magnesium-manganese spinel nanomaterial, characterized in that, Its chemical formula is Mg x Mn2O4, where 0.1≤x≤0.
8.
2. The magnesium defect-type magnesium manganese spinel nanomaterial according to claim 1, characterized in that, 0.3≤x≤0.42。 3. The magnesium defect-type magnesium manganese spinel nanomaterial according to claim 3, characterized in that, x takes the value 0.
36.
4. The method for preparing magnesium-defect-type magnesium-manganese spinel nanomaterials according to any one of claims 1 to 3, characterized in that, Preparation methods include: (1) The initial magnesium manganese spinel nanomaterials were mixed with an acid solution and reacted, and the solid product was obtained by separation; (2) The solid product was washed, dried and ground in sequence to obtain magnesium defect type magnesium manganese spinel nanomaterial.
5. The preparation method according to claim 4, characterized in that, The acid solution is selected from hydrochloric acid solution.
6. The preparation method according to claim 5, characterized in that, The reaction includes dispersing the initial magnesium manganese spinel nanomaterial in an acid solution and reacting the nanomaterial. The initial magnesium manganese spinel nanomaterial has a solid content of 10 mg / mL to 100 mg / mL, and the acid solution has a concentration of 0.1 mol / L to 1 mol / L.
7. The preparation method according to any one of claims 4 to 6, characterized in that, The preparation method satisfies one or more of the following conditions: (i) The reaction includes: stirring continuously at 25℃ to 35℃ for 1h to 6h; (ii) Drying includes: drying temperature of 60℃~100℃, drying time of 8h~16h.
8. Aqueous magnesium-ion battery cathode, characterized in that, The invention includes magnesium-defect magnesium-manganese spinel nanomaterials as described in any one of claims 1 to 3 or magnesium-defect magnesium-manganese spinel nanomaterials prepared by the preparation method described in any one of claims 4 to 7, wherein the magnesium-defect magnesium-manganese spinel nanomaterials are used as positive electrode active materials.
9. An aqueous magnesium-ion battery, characterized in that, It includes the aqueous magnesium-ion battery cathode as described in claim 8.
10. The application of the magnesium defect-type magnesium manganese spinel nanomaterial according to any one of claims 1 to 3 or the magnesium defect-type magnesium manganese spinel nanomaterial prepared by the preparation method according to any one of claims 4 to 7 as a positive electrode active material for aqueous magnesium-ion batteries.