Sodium titanate of a layered crystal structure, preparation method thereof and application thereof in aqueous magnesium ion battery

Abstract

This invention discloses a type of sodium titanate with a layered crystal structure, its preparation method, and its application in aqueous magnesium-ion batteries, belonging to the field of aqueous magnesium-ion battery technology. This invention uses sodium titanate with a layered crystal structure as the negative electrode material in aqueous magnesium-ion batteries. Due to its excellent chemical and structural stability, sodium titanate can achieve reversible magnesium deposition in aqueous magnesium electrolytes. 2+ Intercalation / extraction. This invention synthesizes Na via a hydrothermal method and a high-temperature annealing process. 2 Ti 2 O 5 And Na 2 Ti 3 O 7 Materials. In magnesium chloride electrolyte, both sodium titanate materials exhibit extremely low charge / discharge potentials (Na). 2 Ti 2 O 5 -1.3 to -0.6V vs. SCE; Na 2 Ti 3 O 7 (-1.5 to -1V vs. SCE) and good cycle stability. Furthermore, Na... 2 Ti 2 O 5 The half-cell exhibits a charge-discharge specific capacity of up to 213 mAh / g at a current density of 2 A / g, and maintains a high specific capacity of 150 mAh / g even at a high current density of 10 A / g. The sodium titanate of this invention is an ideal anode material for aqueous magnesium batteries, possessing both low cost and environmental friendliness, and shows great promise for application in the field of aqueous magnesium-ion energy storage.

Description

A type of layered crystal structure sodium titanate, its preparation method, and its application in aqueous magnesium-ion batteries. Technical Field

[0001] This invention belongs to the field of aqueous magnesium-ion battery technology, specifically relating to a type of sodium titanate with a layered crystal structure, its preparation method, and its application in aqueous magnesium-ion batteries. Background Technology

[0002] In recent years, polyvalent metal ions (Zn) 2+ Mg 2+ Ca 2+ Al 3+ Aqueous batteries, such as those for zinc, have attracted widespread attention from researchers due to their abundant resources, high electron transfer characteristics, and inherent safety. Among these, magnesium has even more abundant resources (approximately 280 times the amount found in the Earth's crust compared to zinc), a lighter relative atomic mass (magnesium: 24.31, zinc: 65.38), and a smaller hydrated ionic radius (magnesium: ...). Zinc: This makes aqueous magnesium-ion batteries a promising candidate for the next big trend in low-cost, high-energy / power-density battery research. However, research on aqueous magnesium-ion batteries is still in its early stages, particularly lagging behind in the development of anode materials. The extremely low reduction potential of magnesium metal (-2.37V vs. SHE) makes it prone to violent hydrogen evolution side reactions in water, forming MgO. 2+ The insulating, inert passivation layer significantly reduces its reversibility and cycle stability. Therefore, aqueous magnesium-ion batteries based on magnesium metal anodes will still be difficult to meet the needs of practical applications in the short term.

[0003] Besides magnesium metal, a few organic compounds and inorganic vanadium oxides have been reported as anodes in aqueous magnesium-ion batteries. However, most small organic molecules and vanadium oxide anodes face severe dissolution problems in aqueous electrolytes. Furthermore, the limited number of active sites on the surface of organic molecules causes most organic anodes to exhibit lower magnesium content. 2+ Storage capacity; vanadium-based materials achieve specific capacities close to theoretical values ​​at extremely low current densities through continuous redox reactions of multivalent vanadium, while exhibiting lower Mg content at higher current densities due to reaction kinetic limitations. 2+ Storage capacity.

[0004] Titanium-based materials, as a low-cost anode, possess advantages such as high theoretical capacity (130–350 mAh / g) and low lattice strain, while exhibiting sufficiently low redox potentials (< -1 V vs. SHE) in aqueous electrolytes. However, the reaction potential of titanium-based materials is lower than the hydrogen evolution potential of water (-0.41 V vs. SHE; pH = 7), and the hydrogen evolution side reaction still interferes with the reversible insertion and extraction of ions. Especially for magnesium ions with high ionic potentials, some compact titanium-based materials suffer from interference due to Mg... 2+ High desolvation energy can cause severe electrode polarization, exacerbating side reactions at the solid-liquid interface; completely desolvated bare Mg 2+ Strong interactions with the host lattice may also limit its solid-phase diffusion. Therefore, to date, no titanium-based anode has achieved Mg2+ diffusion in conventional aqueous electrolytes. 2+ Research reports on reversible storage.

[0005] Based on the above reasons, this application is hereby submitted. Summary of the Invention

[0006] Based on the above reasons, and addressing the problems or defects existing in the prior art, the purpose of this invention is to provide a layered crystal structure of sodium titanate, its preparation method, and its application in aqueous magnesium-ion batteries, thereby solving or at least partially solving the aforementioned technical defects in the prior art. The layered crystal structure of sodium titanate of this invention exhibits extremely low magnesium ion insertion / deintercalation potentials (~-1.2V vs. SCE) in conventional magnesium chloride aqueous solutions, demonstrating excellent rate performance and cycle stability. Furthermore, the layered crystal structure of sodium titanate of this invention possesses an open-layer spatial structure, which, when used as a negative electrode material in aqueous magnesium-ion batteries, can reduce the solid-liquid interface desolvation barrier, promote interfacial charge transfer, and effectively mitigate the occurrence of hydrogen evolution side reactions.

[0007] To achieve the first objective of this invention, the technical solution adopted by this invention is as follows:

[0008] A type of sodium titanate with a layered crystal structure, wherein the molecular formula of the sodium titanate is Na₂Ti. n O 2n+1 , where: 2≤n≤3, and n is an integer.

[0009] Specifically, in the above technical solution, the sodium titanate with the layered crystal structure is Na2Ti2O5 or Na2Ti3O7.

[0010] Furthermore, in the above technical solution, the Na2Ti2O5 is in the form of nanowires; and the Na2Ti3O7 is in the form of sea urchin-shaped nanospheres.

[0011] The second objective of this invention is to provide a method for preparing sodium titanate with the layered crystal structure described above, which involves reacting a reaction mixture containing a titanium source and an aqueous solution of an inorganic sodium salt with a hydrothermal reaction followed by high-temperature annealing.

[0012] Specifically, when the layered crystal structure of sodium titanate is Na2Ti2O5, the preparation method of Na2Ti2O5 includes the following steps:

[0013] A clean and dry titanium substrate was placed in the lining of a high-pressure reactor containing sodium hydroxide solution, sealed, and then the sealed reactor was heated to 220°C and reacted at a constant temperature for 24 hours. After the reaction was completed, the titanium substrate was removed, dried, and placed in a tube furnace. It was then heated to 450°C and annealed at a constant temperature for 2 hours under a special atmosphere to obtain a Na2Ti2O5 thin film.

[0014] Furthermore, in a preferred embodiment of the present invention, the concentration of the sodium hydroxide solution is 0.5–2 mol / L.

[0015] Furthermore, in the above technical solution, the special gas atmosphere is composed of hydrogen and argon, for example, it can be composed of 5% (v / v) hydrogen and 95% (v / v) argon.

[0016] Specifically, when the layered crystal structure of sodium titanate is Na2Ti3O7, the preparation method of Na2Ti3O7 includes the following steps:

[0017] Glycerol was uniformly dispersed in an aqueous solution of titanium source according to the specified ratio. Then, sodium hydroxide solution was added dropwise to the resulting mixture according to the specified ratio to obtain a reaction solution. The reaction solution was transferred to the lining of a high-pressure reactor, sealed, and the sealed reactor was heated to 200°C and reacted at a constant temperature for 24 hours. After the reaction was completed, the product was centrifuged, the precipitate was collected, dried, and placed in a tube furnace. The furnace was heated to 450°C and annealed at a constant temperature for 2 hours under a special atmosphere to obtain Na2Ti3O7 powder.

[0018] Furthermore, in a preferred embodiment of the present invention, the concentration of the titanium source aqueous solution is 5-15 g / L.

[0019] Furthermore, in a preferred embodiment of the present invention, the volume ratio of glycerol to the titanium source aqueous solution is 1:(1-10).

[0020] Furthermore, in the above technical solution, the titanium source is any one of tetrabutyl titanate, tetrabutyl titanate, etc.

[0021] Furthermore, in a preferred embodiment of the present invention, the concentration of the sodium hydroxide solution is 5–15 mol / L.

[0022] Furthermore, in a preferred embodiment of the present invention, the volume ratio of the titanium source aqueous solution to the sodium hydroxide solution is (1-5):1.

[0023] Furthermore, in the above technical solution, the special gas atmosphere is composed of hydrogen and argon, for example, it can be composed of 5% (v / v) hydrogen and 95% (v / v) argon.

[0024] A third objective of this invention is to provide the application of sodium titanate with the layered crystal structure described above in aqueous magnesium-ion batteries.

[0025] The fourth objective of this invention is to provide an aqueous magnesium-ion battery anode material, the anode material comprising an anode active material, conductive carbon black and a binder, wherein the anode active material is the Na2Ti3O7 powder described above in this invention.

[0026] Furthermore, in the above technical solution, the mass ratio of the Na2Ti3O7 powder electrode to the conductive carbon black and binder is 6-8:1-3:1-2.

[0027] Furthermore, in the above technical solution, the conductive carbon black is any one of Ketjen black, single-walled carbon nanotubes, multi-walled carbon nanotubes, or Super P.

[0028] Furthermore, in the above technical solution, the adhesive is any one of polytetrafluoroethylene, polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), polyvinylpyrrolidone (PVP), etc.

[0029] The fifth objective of this invention is to provide an aqueous magnesium-ion battery negative electrode sheet, the negative electrode sheet comprising a current collector and a negative electrode material coated and / or filled on the current collector, wherein: the negative electrode material is the aqueous magnesium-ion battery negative electrode material described above or a Na2Ti2O5 thin film.

[0030] The sixth objective of this invention is to provide an aqueous magnesium-ion battery, the battery comprising an electrode core and an aqueous electrolyte, the electrode core and the aqueous electrolyte being sealed within a battery casing, the electrode core comprising a positive electrode, a negative electrode and a separator, wherein the negative electrode is the aqueous magnesium-ion battery negative electrode described above.

[0031] Furthermore, in the above technical solution, the aqueous electrolyte is a conventional magnesium salt aqueous solution, including but not limited to magnesium chloride aqueous solution, other conventional magnesium sulfate aqueous solution, magnesium nitrate aqueous solution, and magnesium acetate aqueous solution, etc.

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

[0033] This invention explores the application of Na₂Ti₂O₅ thin films and Na₂Ti₃O₇ powder in conventional magnesium salt aqueous solutions. As an anode material for aqueous magnesium-ion batteries, the layered crystal structure of sodium titanate described in this invention has a working potential range of -1.7 to 0.4 V. The Na₂Ti₂O₅ half-cell exhibits a charge-discharge capacity as high as 213 mAh / g at a current density of 2 A / g, and shows no significant capacity decay after 100 cycles at a current density of 10 A / g. The preparation method of this invention is convenient, efficient, low-cost, and highly reproducible, possessing certain practical value. Furthermore, this invention is of great significance for the development of anode materials for aqueous magnesium-ion batteries and can be extended to the development of anode materials for other aqueous magnesium-ion batteries. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 shows the X-ray diffraction pattern and scanning electron microscope image of the Na2Ti2O5 thin film obtained in Example 1 of the present invention.

[0036] Figure 2 is an X-ray diffraction and scanning electron microscope image of the Na2Ti3O7 powder obtained in Example 2 of the present invention.

[0037] Figure 3 shows the cyclic voltammetry curves of the Na2Ti2O5 half-cell obtained in Example 1 of this invention in a 1 mol / L magnesium chloride aqueous solution, for the first five cycles and at different scan rates.

[0038] Figure 4 is a charge-discharge curve of the Na2Ti2O5 half-cell obtained in Example 1 of this invention at a current density of 2A / g for the first five cycles.

[0039] Figure 5 shows the rate performance, charge-discharge curve, and long-life cycle performance of the Na2Ti2O5 half-cell obtained in Example 1 of this invention.

[0040] Figure 6 shows the cyclic voltammetry curves, rate performance, and long-life cycle performance of the Na2Ti3O7 half-cell obtained in Example 2 of this invention in a 1 mol / L magnesium chloride aqueous solution. Detailed Implementation

[0041] This invention employs sodium titanate with a layered crystal structure as the negative electrode material for aqueous magnesium-ion batteries. Due to its excellent chemical and structural stability, sodium titanate with a layered crystal structure can achieve reversible Mg transformation in conventional aqueous magnesium electrolytes. 2+Intercalation / De-intercalation. This invention synthesizes Na₂Ti₂O₅ thin films and Na₂Ti₃O₇ powders using titanium foil / tetrabutyl titanate and sodium hydroxide solution as titanium and sodium sources, respectively, through a simple hydrothermal and high-temperature annealing process. In magnesium chloride electrolyte, both sodium titanate materials exhibit extremely low charge / discharge potentials (Na₂Ti₂O₅, -1.3 to -0.6 V vs. SCE; Na₂Ti₃O₇, -1.5 to -1 V vs. SCE) and good cycle stability. Furthermore, the Na₂Ti₂O₅ half-cell achieves a charge / discharge specific capacity of 213 mAh / g at a current density of 2 A / g, and maintains a high specific capacity of 150 mAh / g even at a high current density of 10 A / g. The sodium titanate with a layered crystal structure mentioned in this invention is an ideal anode material for aqueous magnesium batteries, possessing the advantages of low cost and environmental friendliness, and has great application prospects in the field of aqueous magnesium ion energy storage.

[0042] The present invention will be further described in detail below through implementation examples. These implementation examples are carried out based on the technology of the present invention. Detailed implementation methods and specific operating procedures are provided to illustrate the inventiveness of the present invention, but the scope of protection of the present invention is not limited to the following implementation examples.

[0043] Based on the information contained in this application, various modifications to the precise description of the invention can be readily made by those skilled in the art. It should be understood that the scope of the invention is not limited to the defined processes, properties, or components, as these embodiments and other descriptions are merely illustrative of specific aspects of the invention.

[0044] To better understand the invention and not to limit its scope, all figures indicating amounts, percentages, and other numerical values ​​used in this application should, in all cases, be understood to be modified by the word "approximately." Therefore, unless otherwise stated, the numerical parameters listed in the specification are approximate values ​​and may vary depending on the desired properties being sought. Each numerical parameter should at least be considered as obtained based on reported significant figures and through conventional rounding methods.

[0045] The equipment and raw materials used in this invention are all commercially available or commonly used in the field. Unless otherwise specified, the methods in the following embodiments are conventional methods in the field.

[0046] In step (1) of Example 1 below, the titanium foil specifications are not limited to a thickness of 50 μm and a fixed area size; the volume of the polystyrene black inner liner substrate in step (2) is not limited to 100 mL, and the appropriate volume of the reactor inner liner substrate can be adjusted according to the specifications of the cut metal titanium foil.

[0047] Example 1

[0048] The Na2Ti2O5 thin film in this embodiment was prepared by a one-step hydrothermal synthesis followed by high-temperature annealing. The specific preparation method is as follows:

[0049] (1) A commercial titanium foil with an area of ​​5cm*10cm and a thickness of 50μm was polished with 320-grit sandpaper until the surface had no obvious gloss. Then it was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water in sequence, and then placed in an 80℃ oven for drying.

[0050] (2) Place the dried titanium foil into a 100 mL polystyrene black inner liner containing a 1 mol / L sodium hydroxide aqueous solution, seal it, and place the reactor in an oven at 220°C for 24 hours.

[0051] (3) Take out the titanium foil with Na2Ti2O5 grown after the reaction in step (2), wash and dry it, then place it in a tube furnace and heat it to 450°C under the protection of a special gas atmosphere, and keep it at 450°C for 2 hours to obtain a Na2Ti2O5 film; wherein: the special gas atmosphere is composed of 5% (v / v) hydrogen and 95% (v / v) argon.

[0052] Structural and morphological testing:

[0053] The product prepared in Example 1 was subjected to phase analysis and morphological characterization. Figure 1 shows the X-ray diffraction, optical, and scanning electron microscopy (SEM) images of the product prepared in Example 1. As shown in Figure 1a, the synthesized material is Na2Ti2O5, and its diffraction peak positions match the standard spectrum (PDF#47-0124) of monohydrated titanic acid (H2Ti2O5·H2O). Figure 1b shows the optical and SEM images of Na2Ti2O5. The SEM images show that its structure is nanowire-like.

[0054] Example 2

[0055] The preparation method of Na2Ti3O7 powder in this embodiment specifically includes the following steps:

[0056] (1) Disperse 20 mL of glycerol in 100 mL of 10 g / L tetrabutyl titanate aqueous solution, stir vigorously to mix evenly, and then slowly add 50 mL of 10 mol / L NaOH solution and stir evenly.

[0057] (2) Transfer the mixed solution obtained in step (1) to the liner of a stainless steel autoclave, seal it, and hydrothermally heat it at 200°C for 24 hours. After centrifuging and washing the mixed solution, collect the powder sample.

[0058] (3) The dried white sample was collected and placed in a special atmosphere and kept at 450°C for 2 hours to obtain Na2Ti3O7 powder; wherein: the special atmosphere consisted of 5% (v / v) hydrogen and 95% (v / v) argon.

[0059] Structural and morphological testing:

[0060] Phase analysis and morphological characterization were performed on the powder product prepared in Example 2. Figure 2 shows the X-ray diffraction, optical, and scanning electron microscopy (SEM) images of the powder product prepared in Example 2. As shown in Figure 2a, the synthesized material is Na2Ti3O7, and its diffraction peak positions match the standard spectrum (PDF#31-1329), space group P21 / m. Figure 2b shows the optical and SEM images of the powder product prepared in Example 2. The SEM images show that its morphology is that of sea urchin-shaped nanospheres.

[0061] The battery cyclic voltammetry and constant current charge-discharge test methods involved in Application Examples 1 and 2 are as follows: Under constant temperature conditions of 25°C, linear cyclic voltammetry curves were tested using a Wuhan Koster electrochemical workstation, with a test potential window of -1.7 to -0.4V vs. SCE; constant current charge-discharge tests were conducted, with a test voltage range of -1.5 to -0.3V vs. SCE and a test current density of 2 to 20 A / g.

[0062] The specific formulation and preparation method of the electrolyte involved in Application Examples 1 and 2 are as follows:

[0063] Magnesium chloride (MgCl2) was used as the magnesium salt and deionized water as the solvent. An appropriate amount of magnesium chloride was added to deionized water to prepare an aqueous solution of MgCl2 with a molar concentration of 1 mol / L, which was then used as the electrolyte.

[0064] Application Example 1

[0065] The Na2Ti2O5 film prepared in Example 1 was cut to a suitable size (1cm × 0.5cm). Part of the surface Na2Ti2O5 film was scraped off with a scalpel blade and then connected to a titanium foil current collector to serve as the negative electrode of an aqueous magnesium-ion battery. The electrochemical performance of the sodium titanate negative electrode was tested using a three-electrode system, where the counter electrode and the reference electrode were a platinum wire electrode and a saturated calomel electrode, respectively.

[0066] The prepared Na2Ti2O5 negative electrode, electrolyte, platinum sheet electrode, saturated calomel electrode, and other components such as glass containers, test brackets, and electrode wires are assembled into an aqueous magnesium ion half-cell test device, namely a Na2Ti2O5 half-cell.

[0067] Figure 3a and 3b show the linear cyclic voltammetry curves of the Na2Ti2O5 half-cell obtained in this application example at a scan rate of 10 mV / s for the first five cycles and at 2–10 mV / s, respectively. It can be seen that a pair of distinct redox peaks can be observed at potentials of -1.2 V / -1.65 V, and with increasing scan rate, this indicates that the Na2Ti2O5 anode exhibits reversible electrochemical magnesium insertion / extraction performance.

[0068] Figure 4 shows the charge-discharge curves of the Na2Ti2O5 half-cell obtained in this application example for the first five cycles at a charge-discharge current density of 2 A / g. It can be seen that the Na2Ti2O5 anode gradually stabilizes after 5 cycles of activation, and exhibits high reversible capacity (210 mAh / g) and low operating potential (-1.2 V vs. SCE) at a current density of 2 A / g.

[0069] Figure 5 shows the rate and cycle performance of the Na2Ti2O5 half-cell obtained in this application embodiment at different current densities. As shown in Figures 5a-b, the Na2Ti2O5 half-cell obtained in this application embodiment maintains a stable specific capacity at different current densities, and the capacity only shows a slight decrease when the current density returns to the minimum current. In addition, the Na2Ti2O5 half-cell still maintains a high specific capacity of 150 mAh / g at a high current density of 10 A / g, demonstrating its excellent rate cycling performance. In Figure 5c, the Na2Ti2O5 half-cell achieves up to 100 cycles at a current density of 10 A / g, and after activation in the first 20 cycles, it only shows a capacity decrease of 0.13% per cycle in the last 80 cycles, demonstrating excellent cycle stability.

[0070] Application Example 2

[0071] The Na2Ti3O7 powder prepared in Example 2 was used as the negative electrode active material. 7 mg of the Na2Ti3O7 powder was mixed with 2 mg of Ketjen black and 1 mg of polytetrafluoroethylene, and 2 mL of isopropanol was added and stirred evenly to obtain a slurry. The slurry was then rolled into a 10 cm * 10 cm film using a roller press and dried. It was then cut into 1 cm * 1 cm pieces and directly die-cast onto a titanium mesh as the negative electrode sheet of an aqueous magnesium ion battery. The electrochemical performance of the sodium titanate negative electrode was tested using a three-electrode system, where the counter electrode and the reference electrode were a platinum wire electrode and a saturated calomel electrode, respectively.

[0072] The prepared Na2Ti3O7 negative electrode, electrolyte, platinum sheet electrode, saturated calomel electrode, and other components such as glass containers, test brackets, and electrode wires are assembled into an aqueous magnesium ion half-cell test device to obtain a Na2Ti3O7 half-cell.

[0073] The electrochemical performance of the Na2Ti3O7 half-cell in this application example was tested using the same test method as in Application Example 1.

[0074] Figure 6 shows the cyclic voltammetry curves, rate performance, and cycle performance of the Na2Ti3O7 half-cell obtained in this application example. As shown in Figure 6a, Na2Ti3O7 exhibits redox peaks similar to those of Na2Ti2O5 in magnesium chloride aqueous solution. As shown in Figures 6b-c, the Na2Ti3O7 half-cell has a high discharge specific capacity of 150 mAh / g at 2 A / g and can stably cycle 100 times at a current density of 10 A / g. After capacity stabilization for 30 cycles, the capacity decay is only 0.41% per cycle for the remaining 70 cycles.

Claims

1. The application of a layered crystal structure of sodium titanate in an aqueous magnesium-ion battery, characterized in that: The aqueous magnesium-ion battery includes an electrode core and an aqueous magnesium-ion electrolyte, which are sealed within a battery casing. The electrode core includes a positive electrode, a negative electrode, and a separator. The active material of the negative electrode includes sodium titanate with a layered crystal structure. The layered crystal structure sodium titanate is either nanowire-like Na2Ti2O5 or urchin-like nanospheres Na2Ti3O7. The preparation method of the nanowire-like Na2Ti2O5 is as follows: a clean and dry titanium substrate is placed in the liner of a high-pressure reactor containing sodium hydroxide solution, sealed, and then the sealed reactor is heated to 220°C. o The reaction was carried out at a constant temperature of C for 24 hours. After the reaction was completed, the titanium substrate was removed, dried, and placed in a tube furnace, where it was heated to 450°C under a special atmosphere. o Na2Ti2O5 thin film was obtained by constant temperature annealing for 2 hours. The preparation method of the sea urchin-shaped nanospheres Na2Ti3O7 is as follows: Glycerol was uniformly dispersed in a titanium source aqueous solution according to the formula, and then sodium hydroxide solution was added dropwise to the resulting mixture according to the formula to obtain a reaction solution; the reaction solution was transferred to the liner of a high-pressure reactor, sealed, and then the sealed reactor was heated to 200°C. o The reaction was carried out at a constant temperature of C for 24 hours. After the reaction was completed, the product was centrifuged, the precipitate was collected, dried, and then placed in a tube furnace and heated to 450°C under a special atmosphere. o Na2Ti3O7 powder was obtained by constant temperature annealing at C for 2 hours.

2. The application according to claim 1, characterized in that: The aqueous magnesium ion electrolyte is an aqueous solution of MgCl2.

3. A water-based magnesium-ion battery anode material, the anode material comprising an anode active material, conductive carbon black, and a binder, characterized in that: The negative electrode active material is nanowire-shaped Na2Ti2O5 or urchin-shaped nanospheres Na2Ti3O7; wherein: the preparation method of the nanowire-shaped Na2Ti2O5 is as follows: a clean and dry titanium substrate is placed in the lining of a high-pressure reactor containing sodium hydroxide solution, sealed, and then the sealed reactor is heated to 220°C. o The reaction was carried out at a constant temperature of C for 24 hours. After the reaction was completed, the titanium substrate was removed, dried, and placed in a tube furnace, where it was heated to 450°C under a special atmosphere. o Na2Ti2O5 thin film was obtained by constant temperature annealing for 2 hours. The preparation method of the sea urchin-shaped nanospheres Na2Ti3O7 is as follows: Glycerol was uniformly dispersed in a titanium source aqueous solution according to the formula, and then sodium hydroxide solution was added dropwise to the resulting mixture according to the formula to obtain a reaction solution; the reaction solution was transferred to the liner of a high-pressure reactor, sealed, and then the sealed reactor was heated to 200°C. o The reaction was carried out at a constant temperature of C for 24 hours. After the reaction was completed, the product was centrifuged, the precipitate was collected, dried, and then placed in a tube furnace and heated to 450°C under a special atmosphere. o Na2Ti3O7 powder was obtained by constant temperature annealing at C for 2 hours.

4. A negative electrode sheet for an aqueous magnesium-ion battery, the negative electrode sheet comprising a current collector and a negative electrode material coated and / or filled on the current collector, characterized in that: The negative electrode material is the aqueous magnesium ion battery negative electrode material as described in claim 3.

5. An aqueous magnesium-ion battery, the battery comprising an electrode core and an aqueous magnesium-ion electrolyte, the electrode core and the aqueous magnesium-ion electrolyte being sealed within a battery casing, the electrode core comprising a positive electrode, a negative electrode, and a separator, characterized in that: The negative electrode sheet is the aqueous magnesium ion battery negative electrode sheet as described in claim 4.

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