Aluminum-containing heavy water-based electrolyte, preparation method and application thereof

Abstract

This invention discloses an aluminum-containing heavy water-based electrolyte, its preparation method, and its applications. The electrolyte comprises a solvent and a solute. The solvent includes heavy water, a deuterated solvent, and a low-barrier hydrogen bond reconstructing agent. The solute comprises a main aluminum salt and an auxiliary monovalent metal salt. This electrolyte can construct low-barrier hydrogen bonds in solution by controlling the solvent composition, significantly reducing the activity of water in the solution, improving the electrochemical stability of the solution, and suppressing side reactions. Simultaneously, it improves the electrochemical reaction behavior of aluminum in the solution and at the electrolyte / electrode interface, which is beneficial for improving the electrochemical deposition efficiency of aluminum in aqueous solution.

Description

Technical Field

[0001] This invention relates to an electrolyte, its preparation method and application, and particularly to an aluminum-containing heavy water-based electrolyte, its preparation method and application, belonging to the field of aluminum electrochemical reduction technology. Background Technology

[0002] Aluminum's redox potential (-1.66V vs SHE) is lower than that of hydrogen, so it preferentially displaces hydrogen from the water in aqueous solution, resulting in hydrogen evolution corrosion. Meanwhile, according to the potential-pH diagram of the Al-H₂O system, Al… 3+ The thermodynamic stability region of H is outside the thermodynamic stability region of water, therefore when the electrode gains electrons, H + / H2 will take priority over Al 3+ The Al reaction produces a large amount of hydrogen gas, which reduces the current efficiency and makes it difficult to achieve Al reaction in aqueous solution. 3+ The current aluminum smelting method still primarily relies on the traditional Hall-Héroult molten salt electrolysis process, as the goal is to convert aluminum into elemental metal. With advancements in research and technology, room-temperature ionic liquids have provided a new option for low-temperature aluminum electrolysis / electroplating. However, ionic liquids are extremely sensitive to humidity and oxygen, exhibit high toxicity, and are expensive, hindering large-scale application. Therefore, water-based electrolytes offer advantages such as safety, lack of pollution, and low cost. However, achieving the electrochemical reduction of aluminum in aqueous solutions remains a significant challenge in this field.

[0003] The electrochemical stability window of water at room temperature and pressure is relatively narrow, at 1.23V. Water is prone to decomposition during electrochemical reactions, producing hydrogen and oxygen at the electrodes, which limits its application in electrochemical reactions. To address this issue, the composition of the solvent or solute in the electrolyte can be adjusted to create systems such as water-in-salt or molecularly crowded environments. Through the interactions between the components in the electrolyte, the activity of free water can be restrained, thus improving the electrochemical stability of the electrolyte. Hydrogen bonding, as one of the most prevalent forces in aqueous solutions, can form stronger hydrogen bonds with water by introducing substances containing polar atoms such as O, N, and S, compared to the hydrogen bonds between water molecules. This disrupts the original hydrogen bond network in the solution and inhibits the activity of water. However, these hydrogen bonds are usually formed through electrostatic interactions between molecules, and their strength is still much weaker than the covalent bonds between OH groups in water molecules. Therefore, strengthening the hydrogen bonding between water and other molecules, inhibiting the activity of free water, and improving the electrochemical stability of the electrolyte are of great significance for realizing the reversible electrochemical stripping / deposition process of aluminum in aqueous solutions.

[0004] Chinese patent CN202210276495.5 discloses an aqueous electrolyte based on deuterated water, its preparation method, and its application in metal-ion secondary batteries. By replacing all or part of ordinary water with deuterated water, the electrochemical window of the electrolyte is broadened and the occurrence of side reactions is reduced. However, 0-80% organic solvent still needs to be added to this electrolyte, and the volume ratio of deuterated water is more than 30%. The large amount of organic solvent makes it difficult to ensure the safety of the aqueous electrolyte, and it is also difficult to accurately control the solvation structure of aluminum ions in the aqueous electrolyte.

[0005] In conclusion, developing a safe, stable, and high-performance aqueous electrolyte is of great significance for realizing the electrochemical reduction process of aluminum in aqueous solutions, and will help promote the development and application of aluminum reduction technology in room temperature aqueous systems. Summary of the Invention

[0006] To address the problems existing in the prior art, the first objective of this invention is to provide an aluminum-containing heavy water-based electrolyte. This electrolyte, by introducing a substance containing polar atoms into a deuterated solvent, forms strong intramolecular and intermolecular hydrogen bonds, achieving directional reconstruction of the hydrogen bond network in the solution. This effectively limits the activity of water, thereby suppressing the hydrogen evolution side reaction of aluminum in aqueous solutions, improving the reversibility of aluminum in aqueous electrolytes, and exhibiting electrochemical stability. Simultaneously, the added low-barrier hydrogen bond directional reconstruction agent can replace some water molecules in the solvation shell of aluminum ions, achieving the goal of controlling the solvation structure of aluminum ions in the aqueous electrolyte.

[0007] The second objective of this invention is to provide a method for preparing an aluminum-containing heavy water-based electrolyte, which has the advantages of simple process flow, excellent safety performance, and ease of large-scale application.

[0008] The third objective of this invention is to provide an application of an aluminum-containing heavy water-based electrolyte, which can be used as an electrolyte in aqueous aluminum-ion secondary batteries, aqueous aluminum-air batteries, or as an electrolyte in the process of electrodepositing or electroplating aluminum in an aqueous system. When used, it can effectively broaden the electrochemical stability window of the aqueous electrolyte, which is beneficial for adapting to high-voltage cathode materials, and reduces the dissolution of the cathode active material during charge-discharge cycles, which is beneficial for maintaining the structural stability of the cathode material.

[0009] To achieve the above-mentioned technical objectives, the present invention provides an aluminum-containing heavy water-based electrolyte, comprising a solvent and a solute, wherein the solvent comprises heavy water, a deuterated solvent, and a low-barrier hydrogen bond orientation remodeling agent; and the solute comprises a main aluminum salt and an auxiliary monovalent metal salt.

[0010] The technical solution of this invention mainly relies on the synergistic effect between heavy water, deuterated solvent and low-barrier hydrogen bond directional remodeling agent in the solvent, as well as the synergistic effect between the solvent and solute molecules, to achieve the electrochemical stability of the electrolyte under high voltage and regulate the solvation structure of aluminum ions in aqueous electrolyte.

[0011] The interaction mechanism among the components in the aluminum-containing heavy water-based electrolyte of this invention is as follows: On the one hand, deuterium (D) in the solvent is the most important isotope of hydrogen (H) and has two neutrons. Its mass is 100% greater than that of H, and its isotope effect is more pronounced. Therefore, the vibrational frequency of the DO bond formed in deuterated water is lower than that of the HO bond, meaning that the intramolecular and intermolecular hydrogen bonds formed with deuterium are stronger, which is beneficial for reducing the activity of water in the solution. When other substances containing polar atoms are introduced, stronger hydrogen bonds are also formed between polar atoms and deuterium atoms, reducing the distance between deuterium and polar atoms. At the same time, the strong intramolecular and intermolecular hydrogen bonds lower the energy barrier for the transfer of deuterium atoms between deuterated water and polar molecules. This pulling effect also puts deuterium atoms in a delocalized state. At this time, the hydrogen bonds formed between the acceptor and the donor have covalent properties and are more stable. Simultaneously, due to the unique saturation and directionality of hydrogen bonds, the added polar molecules can preferentially interact with deuterium atoms, achieving directional reconstruction of the hydrogen bond network in the solution. This maximally limits the reactivity of water and avoids side reactions. On the other hand, the introduction of deuterium atoms with a large charge density (364 C / mm²) into the solute further enhances the effect. 3 Aluminum ions, when hydrated, form a stable solvated structure with a large solvated ionic radius, but this also reduces ion mobility, leading to decreased solution conductivity and higher solution impedance. Adding a monovalent metal salt can improve solution conductivity, and the cation-rich system can further broaden the electrochemical stability window of the electrolyte, improving solution stability, suppressing side reactions, and improving the reversibility of aluminum in aqueous solution. Furthermore, aluminum ions, under hydration, form stable hydrated aluminum ions (Al(H₂O)₆). 3+ This results in a high desolvation energy barrier during the reduction process, hindering the electrochemical reduction of aluminum ions. The added low-barrier hydrogen bond remodeling agent can replace some water molecules to enter the solvation shell (Al(H2O)) of aluminum ions. x (solvent) 6-x 3+ ), to improve its desolvation process.

[0012] As a preferred embodiment, the heavy water is deuterium oxide with a deuterium atom content of 50-100%.

[0013] As a preferred embodiment, the deuterated solvent is at least one selected from deuterated dimethyl sulfoxide, deuterated acetone, deuterated tetrahydrofuran, deuterated methanol, deuterated trifluoroacetic acid, and deuterated acetonitrile. The deuterated solvent added in this invention can act as a deuterium atom supplement to provide more low-barrier hydrogen bonds centered on deuterium atoms.

[0014] As a preferred embodiment, the deuterated solvent contains 80-100% deuterium atoms.

[0015] As a preferred embodiment, the low-barrier hydrogen bond directional remodeling agent is at least one selected from N,N-dimethylformamide, N,N-dimethylacetamide, phosphoramide, N-methylpyrrolidone, tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, 1,3-dimethylpropylene urea, ethylene glycol, tetraethylene glycol dimethyl ether, tetramethylurea, and sulfolane. The low-barrier hydrogen bond directional remodeling agents selected in this invention are all polar atoms containing lone pairs of electrons, which can form strong interactions with deuterium atoms, resulting in a shorter deuterium atom donor-acceptor distance. Simultaneously, the selected low-barrier hydrogen bond directional remodeling agents are organic compounds containing a large amount of hydrogen, and the deuteration effect converts some heavy water (D₂O) into HOD or H₂O. Furthermore, the selected modifiers all have high DN values ​​and can interact with metal cations in solution, increasing the solubility of the solute, regulating the solvation structure of the cation, and improving the solvation and desolvation behavior of metal cations during electrochemical processes.

[0016] As a preferred embodiment, the deuterated solvent and the low-barrier hydrogen bond directional remodeling agent are miscible with heavy water of different deuterium atom percentages in any proportion.

[0017] As a preferred embodiment, the solvent is composed of heavy water, a deuterated solvent, and a low-barrier hydrogen bond reconstructing agent in a volume ratio of (1-15):(1-3):(1-5). In this invention, the electrochemical stability window of the aqueous solution is broadened by controlling the hydrogen bonds in the solution; therefore, the proportion of heavy water needs to be higher than that of the deuterated solvent and the low-barrier hydrogen bond reconstructing agent to maintain the basic characteristics of the aqueous solution. Furthermore, the deuterated solvent and the low-barrier hydrogen bond reconstructing agent used in this invention are both organic compounds. Excessive addition of these compounds will increase the viscosity of the solution, reduce its conductivity, and decrease its safety. Moreover, excessive organic compounds will create a molecular crowding effect in the solution, affecting the interaction between the low-barrier hydrogen bond reconstructing agent and heavy water, making it difficult to achieve the construction of low-barrier hydrogen bonds. More importantly, excessive organic compounds will hinder the migration of aluminum ions to the electrode interface, affecting the electrochemical behavior of aluminum at the electrode interface and reducing current efficiency.

[0018] As a preferred embodiment, the aluminum salt includes at least one of aluminum sulfate, aluminum sulfate hexadecahydrate, aluminum sulfate octadecahydrate, aluminum chloride, aluminum chloride hexahydrate, aluminum nitrate, aluminum nitrate hydrate, and aluminum trifluoromethanesulfonate. The aluminum salt in this invention is a water-soluble aluminum salt, which, upon dissolution, yields free aluminum ions, which are the main charge carriers in the electrolyte and provide the basic aluminum source for the electrochemical behavior of aluminum.

[0019] As a preferred embodiment, the concentration of the aluminum salt in the electrolyte is 0.5–6 mol / L.

[0020] As a preferred embodiment, the monovalent metal salt includes at least one of lithium chloride, lithium bromide, lithium sulfate, lithium sulfate, lithium nitrate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(pentafluoroethyl)sulfonylimide, sodium chloride, sodium bromide, sodium sulfate, sodium sulfate, sodium nitrate, sodium perchlorate, sodium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, sodium bis(pentafluoroethyl)sulfonylimide, potassium chloride, potassium bromide, potassium sulfate, potassium sulfate, potassium nitrate, potassium perchlorate, potassium bis(trifluoromethanesulfonyl)imide, potassium bis(fluorosulfonyl)imide, potassium trifluoromethanesulfonate, and potassium bis(pentafluoroethyl)sulfonylimide. The monovalent metal salt selected in this invention is a soluble lithium salt, sodium salt, or potassium salt, which can improve the conductivity of the solution. At the same time, the cation-rich system can further broaden the electrochemical stability window of the electrolyte, improve the stability of the solution, suppress side reactions, and improve the reversibility of aluminum in aqueous solution.

[0021] As a preferred embodiment, the concentration of the monovalent metal salt in the electrolyte is 1–20 mol / L.

[0022] As a preferred embodiment, the solute is composed of a main aluminum salt and an auxiliary monovalent metal salt in a molar ratio of 1:(2-9).

[0023] The present invention also provides a method for preparing an aluminum-containing heavy water-based electrolyte, which involves uniformly mixing a solvent containing heavy water, a deuterated solvent, and a low-barrier hydrogen bond orientation reconstruction modifier, and then uniformly mixing it with a solute to obtain the electrolyte.

[0024] As a preferred embodiment, the mixing conditions are 40–80°C and the mixing time is 20–60 min. Under the mixing conditions of this invention, the solvation between the solvent and the metal cation can be promoted, better achieving the directional reconstruction of the hydrogen bond network in the solution and improving the stability of the solution.

[0025] This invention also provides an application of an aluminum-containing heavy water-based electrolyte. When used as an electrolyte in aqueous aluminum-ion secondary batteries, aqueous aluminum-air batteries, or in the electrodeposition or electroplating of aluminum in an aqueous system, it effectively broadens the electrochemical stability window of the aqueous electrolyte, facilitating compatibility with high-voltage cathode materials. It also reduces the dissolution of the cathode active material during charge-discharge cycles, thus maintaining the structural stability of the cathode material. Furthermore, when applied in electroplating, it effectively improves the aluminum electrodeposition process and efficiency, increases current efficiency, and results in a denser electroplated layer.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1) This invention reconstructs the hydrogen bond network of the solution by controlling the solvent composition, forming a large number of low-barrier hydrogen bonds. Compared with methods such as high-concentration solutions, this greatly broadens the electrochemical stability window of aqueous solutions, increases the overpotential of hydrogen evolution and oxygen evolution side reactions, and increases the Tafel slope by 2 to 4 times, resulting in slower reaction kinetics.

[0028] 2) This invention provides a wider electrochemical stability window for the electrolyte, which is beneficial for suppressing the occurrence of side reactions. The current efficiency of the electroplating solution is increased to over 90%, while the electrochemical reaction process is more stable.

[0029] 3) For aqueous aluminum-ion batteries, the electrolyte proposed in this invention is beneficial for adapting to high-voltage cathode materials during application and reduces the dissolution of cathode active materials during charge-discharge cycles, which helps maintain the structural stability of cathode materials.

[0030] 4) The electrolyte system designed in this invention has a simple preparation method, excellent safety performance, and is easy to apply on a large scale.

[0031] 5) The aluminum-containing heavy water-based electrolyte provided by this invention introduces substances containing polar atoms into the deuterated solvent, forming strong intramolecular and intermolecular hydrogen bonds. This achieves directional reconstruction of the hydrogen bond network in the solution, effectively limiting the activity of water and thus suppressing the hydrogen evolution side reaction of aluminum in aqueous solutions. This improves the reversibility of aluminum in aqueous electrolytes and exhibits electrochemical stability. Simultaneously, the added low-barrier hydrogen bond directional reconstruction agent can replace some water molecules in the solvation shell of aluminum ions, achieving the purpose of regulating the solvation structure of aluminum ions in aqueous electrolytes. Attached Figure Description

[0032] Figure 1 A schematic diagram showing the different hydrogen bonds formed between a low-barrier hydrogen bond directional remodeling agent (N,N-dimethylformamide) molecule, water, and heavy water molecules. Detailed Implementation

[0033] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0034] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0035] Unless otherwise specified, all reagents and raw materials used in this invention are commercially available products or products that can be prepared by known methods.

[0036] Example 1

[0037] Heavy water (99 atom%), deuterated methanol (99.8 atom%), and N,N-dimethylformamide were weighed in a volume ratio of 10:1:3 and mixed uniformly at 60°C for 30 min. Then, measured amounts of aluminum sulfate (2 mol / L) and sodium sulfate (5 mol / L) were added to the prepared mixed solution. The mixture was stirred continuously at 60°C until the solution became clear. The resulting solution was used as the electrolyte for an aqueous aluminum-ion battery.

[0038] Comparative Example 1

[0039] This comparative example is basically the same as Example 1, except that ordinary pure water is used instead of heavy water.

[0040] Comparative Example 2

[0041] This comparative example is basically the same as Example 1, except that deuterated methanol is not added.

[0042] Comparative Example 3

[0043] This comparative example is basically the same as Example 1, except that N,N-dimethylformamide is not added.

[0044] Comparative Example 4

[0045] This comparative example is basically the same as Example 1, except that sodium sulfate is not added.

[0046] Comparative Example 5

[0047] This comparative example is basically the same as Example 1, except that the solvent is mixed and then directly added to the solute and mixed until the solution is clear, instead of mixing uniformly at 60°C for 30 minutes before adding the solute.

[0048] Comparative Example 6

[0049] This comparative example is basically the same as Example 1, except that the volume ratio of heavy water (99 atom%), deuterated methanol (99.8 atom%), and N,N-dimethylformamide is 25:1:3.

[0050] Comparative Example 7

[0051] This comparative example is basically the same as Example 1, except that the volume ratio of heavy water (99 atom%), deuterated methanol (99.8 atom%) and N,N-dimethylformamide is 10:1:10.

[0052] Example 2

[0053] Heavy water (99 atom%), deuterated dimethyl sulfoxide (99 atom%), and tetrahydrofuran were weighed in a volume ratio of 11:2:2 and mixed uniformly at 50°C for 50 min. Then, measured amounts of aluminum trifluoromethanesulfonate and lithium trifluoromethanesulfonate were weighed at 3 mol / L and 18 mol / L, respectively, and added to the above-prepared mixed solution. The mixture was stirred continuously at 50°C until the solution became clear. The resulting solution was used as the electrolyte for an aqueous aluminum-ion battery.

[0054] Example 3

[0055] Heavy water (99 atom%), deuterated acetone (99.9 atom%), and sulfolane were weighed in a volume ratio of 8:2:3 and mixed uniformly at 70°C for 40 min. Then, quantities of aluminum trifluoromethanesulfonate and lithium difluorosulfonylimide were weighed at 5 mol / L and 13 mol / L, respectively, and added to the above-prepared mixed solution. The mixture was stirred continuously at 60°C until the solution became clear. The resulting solution was used as the electrolyte for an aqueous aluminum-ion battery.

[0056] Examples 1-3 and Comparative Examples 1-7 were all used as electrolytes in aqueous ion batteries. A platinum sheet (1×1cm) was used as the working electrode. 2 Aluminum is used as the counter electrode (1×1cm) 2 Using an Ag / ACl electrode as the reference electrode, the electrochemical stability window, hydrogen evolution overpotential, and oxygen evolution overpotential of the electrolyte were tested in a three-electrode system at a scan rate of 0.01 V / s. Al / / Al symmetric cells were assembled using pure aluminum electrodes and tested at 0.1 mA / cm². 2 The cycle stability of the battery under different electrolyte systems was tested at a given current density. The test results are shown in Tables 1 and 2, respectively.

[0057] Table 1 Comparison of electrochemical stability windows for different electrolyte systems

[0058]

[0059] Table 2 Electrochemical performance of Al / / Al symmetric cells

[0060]

[0061] The results from the above examples and comparative examples show that by replacing ordinary water with heavy water to obtain a heavy water-based solution, and by reconstructing the hydrogen bond network in the heavy water-based solution with additives, the electrochemical stability of the solution is broadened, the occurrence of side reactions in the aluminum-ion battery is suppressed, the cycle stability of the negative electrode is improved, the electrochemical performance of the battery is improved, and the cycle life of the battery is increased. This is conducive to obtaining a full cell with better performance and promotes the development and large-scale application of aluminum-ion batteries.

[0062] Example 4

[0063] Heavy water (80 atom%), deuterated methanol (95 atom%), and dimethyl sulfoxide were weighed in a volume ratio of 7:2:2 and mixed uniformly at 40°C for 50 min. Then, measured amounts of aluminum chloride and lithium chloride were weighed at 3 mol / L and 10 mol / L, respectively, and added to the prepared mixed solution. The mixture was stirred continuously at 40°C until the solution became clear. The resulting solution was used as the electroplating solution.

[0064] Comparative Example 8

[0065] This comparative example is basically the same as Example 4, except that pure water is used instead of heavy water.

[0066] Comparative Example 9

[0067] This comparative example is basically the same as Example 4, except that deuterated methanol is not added.

[0068] Comparative Example 10

[0069] This comparative example is basically the same as Example 4, except that dimethyl sulfoxide is not added.

[0070] Example 5

[0071] Heavy water (70 atom%), deuterated acetone (85 atom%), and tetramethylurea were weighed in a volume ratio of 7:1:5 and mixed uniformly at 70°C for 30 min. Then, quantities of aluminum trifluoromethanesulfonate and lithium bis(trifluoromethanesulfonyl)imide were weighed at 5 mol / L and 12 mol / L, respectively, and added to the above-prepared mixed solution. The mixture was stirred continuously at 70°C until the solution became clear. The resulting solution was used as the electroplating solution.

[0072] Example 6

[0073] Heavy water (80 atom%), deuterated acetonitrile (95 atom%), and N,N-dimethylacetamide were weighed in a volume ratio of 7:3:4 and mixed uniformly at 70°C for 30 min. Then, measured amounts of aluminum nitrate (4 mol / L) and sodium trifluoromethanesulfonate (15 mol / L) were added to the prepared mixed solution. The mixture was stirred continuously at 70°C until the solution became clear. The resulting solution was used as the electroplating solution.

[0074] Examples 4-6 and Comparative Examples 8-10 all involve applications in the electroplating process. Copper was used as the anode, and pure aluminum sheets as the cathode, at a voltage of 0.5 mA / cm². 2 Constant current electroplating was performed at a current density for 10 hours, with each electrode having an effective area of ​​1×1 cm². 2 The electroplating temperature was 25℃, and the test results are shown in Table 3.

[0075] Table 3 Comparison of Key Electroplating Parameters

[0076]

[0077] As can be seen from the above embodiments and comparative examples, in heavy water-based electrolytes, due to the improved electrochemical stability of the solution, side reactions are suppressed during electroplating, improving the electrodeposition process and efficiency of aluminum and effectively increasing current efficiency. At the same time, electroplating in the heavy water-based electrolyte proposed in this invention results in a denser electroplated layer, providing theoretical support and reference for aluminum electroplating and electrodeposition in aqueous solutions.

Claims

1. An aluminum-containing heavy water-based electrolyte, comprising a solvent and a solute, characterized in that: The solvent comprises heavy water, a deuterated solvent, and a low-barrier hydrogen bond directional remodeling agent; The solute comprises a main aluminum salt and an auxiliary monovalent metal salt; The heavy water is deuterium oxide with a deuterium atom content of 50-100%; The deuterated solvent is at least one of deuterated dimethyl sulfoxide, deuterated acetone, deuterated tetrahydrofuran, deuterated methanol, deuterated trifluoroacetic acid, and deuterated acetonitrile; The deuterated solvent contains 80-100% deuterium atoms. The low-barrier hydrogen bond directional remodeling agent is at least one of N,N-dimethylformamide, N,N-dimethylacetamide, phosphoramide, N-methylpyrrolidone, tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, 1,3-dimethylpropylene urea, ethylene glycol, tetraethylene glycol dimethyl ether, tetramethylurea, and sulfolane. The solvent is composed of heavy water, deuterated solvent and low-barrier hydrogen bond directional reconstruction agent in a volume ratio of (1~15):(1~3):(1~5); The aluminum salt includes at least one of aluminum sulfate, aluminum sulfate hexadecadehydrate, aluminum sulfate octadecadehydrate, aluminum chloride, aluminum chloride hexahydrate, aluminum nitrate, aluminum nitrate hydrate, and aluminum trifluoromethanesulfonate; The concentration of the aluminum salt in the electrolyte is 0.5~6 mol / L; The concentration of the monovalent metal salt in the electrolyte is 1~20 mol / L.

2. The aluminum-containing heavy water-based electrolyte according to claim 1, characterized in that: The monovalent metal salt includes at least one of lithium chloride, lithium bromide, lithium sulfate, lithium sulfate, lithium nitrate, lithium perchlorate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium trifluoromethanesulfonate, lithium bis(pentafluoroethyl)sulfonylimide, sodium chloride, sodium bromide, sodium sulfate, sodium sulfate, sodium nitrate, sodium perchlorate, sodium bis(trifluoromethanesulfonyl)imide, sodium bis(fluorosulfonyl)imide, sodium trifluoromethanesulfonate, sodium bis(pentafluoroethyl)sulfonylimide, potassium chloride, potassium bromide, potassium sulfate, potassium sulfate, potassium nitrate, potassium perchlorate, potassium bis(trifluoromethanesulfonyl)imide, potassium bis(fluorosulfonyl)imide, potassium trifluoromethanesulfonate, and potassium bis(pentafluoroethyl)sulfonylimide.

3. The aluminum-containing heavy water-based electrolyte according to claim 1 or 2, characterized in that: The solute is composed of a main aluminum salt and an auxiliary monovalent metal salt in a molar ratio of 1:(2~9).

4. A method for preparing an aluminum-containing heavy water-based electrolyte as described in any one of claims 1 to 3, characterized in that: The solvent, which includes heavy water, deuterated solvent, and low-barrier hydrogen bond orientation reconstruction modifier, is mixed evenly and then mixed with the solute to obtain the final product.

5. The application of an aluminum-containing heavy water-based electrolyte as described in any one of claims 1 to 3, characterized in that: It can be used as an electrolyte in aqueous aluminum-ion secondary batteries and aqueous aluminum-air batteries, or as an electrolyte in the process of electrodepositing or electroplating aluminum in an aqueous solution system.

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