Electrolyte and method of making same, rechargeable aluminum battery

Abstract

The application relates to the technical field of aluminum batteries, in particular to an electrolyte, a preparation method thereof and a rechargeable aluminum battery, wherein the preparation method comprises the following steps: uniformly mixing an aluminum salt, a functional additive and a diluent according to a molar ratio of (1.1-5.1):1:(0.1-10) to obtain an electrolyte; wherein the functional additive is a compound capable of forming an ionic liquid or a eutectic solvent with the aluminum salt, and the diluent comprises one or more of benzene and derivatives thereof. In the application, the diluent is composed of benzene compounds containing large pi bonds, which can interact with the functional additive, so that the electrostatic attraction between anions and cations in the aluminum salt-functional additive electrolyte system is reduced, the viscosity of the aluminum salt-functional additive electrolyte system is reduced, the diffusion rate of active ions in the aluminum salt-functional additive electrolyte system is improved, and the Coulomb efficiency and cycle life of the aluminum battery are effectively improved.

Description

Technical Field

[0001] This invention relates to the field of aluminum battery technology, and more particularly to electrolytes and their preparation methods, and rechargeable aluminum batteries. Background Technology

[0002] Rechargeable aluminum batteries have become a research hotspot in recent years due to their advantages such as high safety, low cost, and high theoretical specific capacity of electrode materials. However, the high viscosity and low ion transport rate of the electrolyte in aluminum-ion batteries lead to the growth of aluminum dendrites under high current, resulting in a decrease in the coulombic efficiency and a shortened lifespan of aluminum-ion batteries.

[0003] To reduce the viscosity of aluminum-ion battery electrolytes, hydrofluoroether additives are usually added. However, due to the low solubility of hydrofluoroether additives in aluminum-ion battery electrolytes, the viscosity of aluminum-ion battery electrolytes cannot be effectively reduced.

[0004] Therefore, how to reduce the viscosity of aluminum-ion battery electrolyte, increase the ion transport rate of aluminum-ion battery electrolyte, and thus improve the coulombic efficiency and cycle life of aluminum-ion batteries remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] This application proposes an electrolyte and its preparation method, as well as a rechargeable aluminum battery, aiming to reduce the viscosity of the aluminum battery electrolyte, thereby improving the coulombic efficiency and cycle life of the aluminum battery.

[0006] In a first aspect, embodiments of this application provide a method for preparing an electrolyte, comprising the following steps: Aluminum salt, functional additives, and diluents are mixed evenly at a molar ratio of (1.1~5.1):1:(0.1~10) to obtain the electrolyte; wherein, The functional additive is a compound that can form an ionic liquid or a eutectic solvent with the aluminum salt, and the diluent includes one or more of benzene and its derivatives.

[0007] In some embodiments, the benzene derivative has the following structural formula: R1, R2, R3, R4, R5, and R6 are independently selected from any one of hydrogen atoms, halogen atoms, amino groups and their derivatives, C1-C6 alkyl groups and their derivatives, and C1-C6 alkoxy groups and their derivatives.

[0008] In some embodiments, the benzene derivative includes one or more of toluene, propylbenzene, o-difluorobenzene, aniline-fluorobenzene, trifluoroaniline, m-difluorobenzene, p-difluorobenzene, trifluorobenzene, hexafluorobenzene, trifluoromethoxybenzene, and trifluoromethylbenzene.

[0009] In some embodiments, the functional adjuvant includes one or more of 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, acetamide, propionamide, N,N-dimethylacetamide, tetrabutylammonium chloride, pyridine and its derivatives, pyrrole and its derivatives, piperidine and its derivatives, urea, methylurea, and thiourea.

[0010] In some embodiments, the aluminum salt includes AlCl3.

[0011] In some embodiments, the aluminum salt, the functional additive, and the diluent are mixed uniformly in a molar ratio of (1.1~1.7):1:(1~10).

[0012] Secondly, embodiments of this application provide an electrolyte prepared using the preparation method described in the first aspect.

[0013] In some embodiments, the electrolyte contains active ions, including [Al₂Cl₇]. - and [AlCl4] - At least one of them.

[0014] Thirdly, embodiments of this application also propose a rechargeable aluminum battery, which includes an electrolyte prepared by the preparation method described in the first aspect, or includes an electrolyte as described in the second aspect.

[0015] In some embodiments, the aluminum battery further includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is a polyolefin separator or a glass fiber separator.

[0016] Compared with the prior art, this technical solution has at least the following technical advantages: The technical solution of this application creatively reduces the viscosity of the aluminum salt-functional additive electrolyte system by adding a benzene-based diluent, thereby increasing the ion transport rate of the aluminum salt-functional additive electrolyte system and thus improving the coulombic efficiency and cycle life of the aluminum battery. In this application's technical solution, the functional additive provides ligands or cations that react with aluminum salts to generate active ions. Since the diluent is composed of benzene compounds containing large π bonds, it interacts with the functional additive, reducing the electrostatic attraction between anions and cations in the aluminum salt-functional additive electrolyte system. This lowers the viscosity of the aluminum salt-functional additive electrolyte system and increases the diffusion rate of active ions, thereby increasing the average coulombic efficiency of the aluminum battery at high current densities. Furthermore, it avoids uneven deposition of aluminum ions at the tips, enabling the deposition of aluminum ions to form smaller and denser spherical nuclei. This facilitates the decomposition of aluminum deposits on the electrode surface of the aluminum battery, forming an SEI interface conducive to active ion transport, accelerating planar deposition of aluminum ions, and inhibiting the growth of aluminum dendrites. This effectively improves the coulombic efficiency and cycle life of the aluminum battery. In addition, the electrolyte of this application has excellent compatibility with commercially available separators such as traditional glass fiber separators and polyolefin separators, significantly reducing the manufacturing cost of aluminum batteries. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic flowchart of the preparation method according to an embodiment of this application; Figure 2 The aluminum battery prepared in Example 1 operates at 3 mA / cm 2 Constant current deposition 0.1 mAh / cm 2 Scanning tunneling microscope image of aluminum nucleation; Figure 3 The aluminum battery prepared in Example 1 operates at 3 mA / cm 2 Constant current deposition 3mAh / cm 2 Scanning tunneling microscope image of aluminum nucleation; Figure 4 The aluminum battery prepared in Comparative Example 1 was tested at 3 mA / cm. 2 Constant current deposition 0.1 mAh / cm 2 Scanning tunneling microscope image of aluminum nucleation; Figure 5 The aluminum battery prepared in Comparative Example 1 was tested at 3 mA / cm. 2 Constant current deposition 3mAh / cm 2 Scanning tunneling microscope image of aluminum nucleation; Figure 6 The circuit performance diagram is shown for the aluminum battery prepared in Example 1. Figure 7 The graph shows the cycle performance of the aluminum battery prepared in Comparative Example 1. Detailed Implementation

[0019] To better understand the technical solution of the present invention, the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0020] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0021] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0022] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0023] Rechargeable aluminum batteries have become a research hotspot in recent years due to their advantages such as high safety, low cost, and high theoretical specific capacity of electrode materials. However, the high viscosity and low ion transport rate of the electrolyte in aluminum-ion batteries lead to the growth of aluminum dendrites under high current, resulting in a decrease in the coulombic efficiency and a shortened cycle life of aluminum-ion batteries.

[0024] Therefore, how to reduce the viscosity of aluminum-ion battery electrolyte, increase the ion transport rate of aluminum-ion battery electrolyte, and thus improve the coulombic efficiency and cycle life of aluminum-ion batteries is a technical problem that urgently needs to be solved in this field.

[0025] Therefore, in the first aspect, this application proposes a method for preparing an electrolyte.

[0026] In this embodiment of the application, the preparation method includes the following steps: S100. Aluminum salt, functional additives, and diluent are mixed evenly at a molar ratio of (1.1~5.1):1:(0.1~10) to obtain an electrolyte; wherein, The functional additive is a compound that can form an ionic liquid or a eutectic solvent with the aluminum salt, and the diluent includes one or more of benzene and its derivatives.

[0027] The technical solution of this application creatively reduces the viscosity of the aluminum salt-functional additive electrolyte system by adding a benzene-based diluent, thereby increasing the ion transport rate of the aluminum salt-functional additive electrolyte system and thus improving the coulombic efficiency and cycle life of the aluminum battery. In this application's technical solution, the functional additive provides ligands or cations that react with aluminum salts to generate active ions. Since the diluent is composed of benzene compounds containing large π bonds, it interacts with the functional additive, reducing the electrostatic attraction between anions and cations in the aluminum salt-functional additive electrolyte system. This lowers the viscosity of the aluminum salt-functional additive electrolyte system and increases the diffusion rate of active ions, thereby increasing the average coulombic efficiency of the aluminum battery at high current densities. Furthermore, it avoids uneven deposition of aluminum ions at the tips, enabling the deposition of aluminum ions to form smaller and denser spherical nuclei. This facilitates the decomposition of aluminum deposits on the electrode surface of the aluminum battery, forming an SEI interface conducive to active ion transport, accelerating planar deposition of aluminum ions, and inhibiting the growth of aluminum dendrites. This effectively improves the coulombic efficiency and cycle life of the aluminum battery. In addition, the electrolyte of this application has excellent compatibility with commercially available separators such as traditional glass fiber separators and polyolefin separators, significantly reducing the manufacturing cost of aluminum batteries.

[0028] In the technical solution of this application, aluminum salt, functional additives and diluent are mixed in a molar ratio of (1.1~5.1):1:(0.1~10). If the amount of diluent added is too low, the viscosity of the electrolyte cannot be reduced, and the coulombic efficiency and cycle performance of the aluminum battery cannot be effectively improved. If the amount of diluent added is too high, the aluminum salt-functional additive electrolyte system cannot provide sufficient active material required for the aluminum deposition and dissolution reaction, which will result in poor battery performance.

[0029] The preparation method of this application will be further described below: In the embodiments of this application, the molar ratio of aluminum salt to functional additive is (1.1~5.1):1, specifically it can be 1:1, 2.1:1, 3.1:1, 4.1:1, 5.1:1 or any value between them.

[0030] In the embodiments of this application, the molar ratio of the functional additives and diluents is 1:(0.1~10), specifically 1:0.1, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10 or any value between them.

[0031] Preferably, the molar ratio of aluminum salt, functional additives and diluent is (1.1~1.7):1:(1~10).

[0032] In the embodiments of this application, the order of mixing aluminum salt, functional additives and diluent is not particularly limited. More commonly, aluminum salt and functional additives are first mixed evenly, and then diluent is added to the aluminum salt-functional additive mixture system and stirred evenly to obtain electrolyte.

[0033] In some embodiments, the diluent and the aluminum salt-functional additive mixture are mixed and stirred evenly under heating conditions, with the heating temperature not exceeding 65°C.

[0034] In this embodiment, the structural formula of the benzene derivative is shown below: R1, R2, R3, R4, R5, and R6 are independently selected from any one of the following groups: hydrogen atom, halogen atom, amino group and its derivatives, C1-C6 alkyl group and its derivatives, C1-C6 alkoxy group and its derivatives.

[0035] In a preferred embodiment, the diluent comprises a benzene derivative, wherein some of R1, R2, R3, R4, R5, and R6 in the benzene derivative are selected from hydrogen atoms, and the other part is selected from fluorine atoms; more preferably, the number of fluorine atoms in the benzene derivative does not exceed two. In this case, the prepared electrolyte has a wider chemical window and better electrochemical performance.

[0036] In some embodiments, the benzene derivative includes one or more of toluene, propylbenzene, o-difluorobenzene, aniline-fluorobenzene, trifluoroaniline, m-difluorobenzene, p-difluorobenzene, trifluorobenzene, hexafluorobenzene, trifluoromethoxybenzene, and trifluoromethylbenzene.

[0037] In this embodiment, the functional additives may be commonly used functional additives for preparing aluminum battery electrolytes in the art.

[0038] In some embodiments, the functional adjuvant includes one or more of 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, acetamide, propionamide, N,N-dimethylacetamide, tetrabutylammonium chloride, pyridine and its derivatives, pyrrole and its derivatives, piperidine and its derivatives, urea, methylurea, and thiourea.

[0039] In this embodiment, the aluminum salt can be the aluminum salt commonly used in the art for preparing aluminum battery electrolytes.

[0040] In some embodiments, the aluminum salt includes AlCl3.

[0041] Secondly, this application provides an electrolyte prepared by the method described in the first aspect.

[0042] In this embodiment, the electrolyte includes an electrolyte and a diluent, and the electrolyte is prepared by mixing an aluminum salt with a functional additive.

[0043] Understandably, in the embodiments of this application, the electrolyte contains active ions and cations, which are generated by the reaction of aluminum salts with functional additives. During the charging and discharging process of the aluminum battery, the active ions act as aluminum ion transport carriers.

[0044] In some embodiments, the active ion includes [Al₂Cl₇]. - and [AlCl4] - One or more of these, during the charging and discharging process, the active ions undergo the following reactions: .

[0045] In this application, the type of cation depends on the components of the functional additive, and this application does not impose any particular limitation on it.

[0046] In some embodiments, the concentration of active ions in the electrolyte is between 0.11 mol / L and 4 mol / L, specifically 0.11 mol / L, 0.16 mol / L, 0.22 mol / L, 0.26 mol / L, 0.31 mol / L, 0.36 mol / L, 4 mol / L, or any value between them. A suitable concentration of active ions in the electrolyte is beneficial for improving the coulombic efficiency and cycle performance of aluminum batteries.

[0047] Thirdly, this application also proposes a rechargeable aluminum battery, which includes an electrolyte prepared by the method of the first aspect, or includes an electrolyte of the second aspect.

[0048] Specifically, the rechargeable aluminum battery also includes a positive electrode, a negative electrode, and a separator, with the separator disposed between the positive and negative electrode.

[0049] In some preferred embodiments, the separator is selected from commercially available polyolefin separators for lithium batteries and glass fiber separators traditionally used in aluminum batteries.

[0050] In existing technologies, the high viscosity of the electrolyte used in aluminum batteries results in poor wettability of the separator, making commercially available separators such as polyolefin separators unsuitable for its application. However, in the aluminum battery of this application, the viscosity of the electrolyte has been significantly reduced, resulting in significantly enhanced wettability of the separator. This not only improves compatibility with traditional glass fiber separators but also enhances compatibility with commercially available separators such as polyolefin separators, thereby significantly reducing the manufacturing cost of aluminum batteries.

[0051] In some embodiments, the method for preparing an aluminum battery includes the following steps: Preparation of positive electrode sheet; Preparation of negative electrode sheet; The positive electrode, negative electrode, and separator are assembled to obtain a battery module; Electrolyte is injected into the battery module to obtain a secondary battery.

[0052] In some implementations, aluminum foil is used for the negative electrode and copper foil is used for the positive electrode.

[0053] The embodiments of this application will be further described below with reference to several examples. However, the embodiments of this application are not limited to the specific embodiments described below.

[0054] Example 1 (I) Preparation of electrolyte At room temperature, in an argon-protected glove box, prepare 2.5g of electrolyte as follows: First, 1.3 mol of AlCl3 was slowly added to 1 mol of 1-ethyl-3-methylimidazolium chloride to prepare the electrolyte before mixing. 5 mol of fluorobenzene was slowly added to the electrolyte before mixing and stirred at room temperature to obtain a homogeneous mixed electrolyte with a fluorobenzene mass fraction of 60%.

[0055] (II) Preparation of aluminum metal batteries The preparation steps are as follows: A coin cell was assembled using copper foil as the positive electrode, aluminum foil as the negative electrode, and a polyolefin membrane as the separator, with 80 μL of the electrolyte prepared above.

[0056] Example 2 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with 1-butyl-3-methylimidazolium chloride.

[0057] Example 3 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with acetamide.

[0058] Example 4 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with acetamide, and fluorobenzene is replaced with benzene.

[0059] Example 5 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of AlCl3 was increased from 1.3 mol to 1.5 mol, and the molar amount of fluorobenzene was decreased from 5 mol to 1 mol.

[0060] Example 6 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with propionamide, and the mixture is heated and stirred at 60°C.

[0061] Example 7 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride was replaced with urea, and fluorobenzene was replaced with o-fluorobenzene. After heating and stirring at 60°C, o-fluorobenzene still could not be completely dissolved in the electrolyte before mixing, and the liquid clearly separated into layers.

[0062] In the preparation of aluminum metal batteries, the supernatant of the electrolyte is assembled into the battery.

[0063] Example 8 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with 4-ethylpyridine, fluorobenzene is replaced with toluene, and the mixture is heated and stirred at 60°C.

[0064] Example 9 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of AlCl3 was increased from 1.3 mol to 1.5 mol, 1-ethyl-3-methylimidazolium chloride was replaced with tetrabutylammonium chloride, and fluorobenzene was replaced with trifluorobenzene. After heating and stirring at 60°C, trifluorobenzene still could not completely dissolve in the electrolyte before mixing, and the liquid clearly separated into layers.

[0065] In the preparation of aluminum metal batteries, the supernatant of the electrolyte is assembled into the battery.

[0066] Example 10 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with N,N-dimethylacetamide, and heating and stirring at 60°C are required.

[0067] Example 11 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with methylurea, and fluorobenzene is replaced with m-difluorobenzene.

[0068] Example 12 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with thiourea, and fluorobenzene is replaced with p-difluorobenzene.

[0069] Example 13 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with 1-methyl-1-butylpyrrolidine chloride, and fluorobenzene is replaced with hexafluorobenzene.

[0070] Example 14 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with n-butyl-n-methylpiperidine chloride, and fluorobenzene is replaced with trifluoromethoxybenzene.

[0071] Example 15 The difference from Example 1 is as follows: In the preparation of the electrolyte, fluorobenzene is replaced with trifluoromethylbenzene.

[0072] Example 16 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of fluorobenzene was increased from 5 mol to 10 mol.

[0073] Example 17 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of fluorobenzene was reduced from 5 mol to 1 mol.

[0074] Example 18 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of fluorobenzene was reduced from 5 mol to 0.1 mol.

[0075] Example 19 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of AlCl3 was increased from 1.3 mol to 4.8 mol.

[0076] Comparative Example 1 The difference from Example 1 is as follows: No fluorobenzene is added during the preparation of the electrolyte.

[0077] Comparative Example 2 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of fluorobenzene was increased from 5 mol to 15 mol.

[0078] Comparative Example 3 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with acetamide, and fluorobenzene is not added.

[0079] Comparative Example 4 The difference from Example 1 is as follows: In the preparation of the electrolyte, 1-ethyl-3-methylimidazolium chloride is replaced with thiourea, fluorobenzene is not added, and heating and stirring at 60°C are required.

[0080] Comparative Example 5 The difference from Example 1 is as follows: In the preparation of the electrolyte, the molar amount of AlCl3 was increased from 1.3 mol to 8 mol, and no fluorobenzene was added.

[0081] The aluminum batteries prepared in each embodiment and comparative example were subjected to electrochemical performance testing.

[0082] The testing method is as follows: Viscosity test of electrolyte: The prepared electrolyte was placed in a glove box (H2O and O2 content less than 0.1 ppm) and the viscosity was measured with a viscometer.

[0083] Electrochemical performance testing of aluminum batteries: A blue battery testing system was used, with a speed of 0.5 mA / cm². 2 Discharge to 0.5 mAmAh / cm 2 0.5 mA / cm 2 Charge to 0.6 V, and record the cycle time and coulomb efficiency.

[0084] The electrolyte preparation conditions, electrolyte viscosity, and aluminum battery performance test results for each embodiment and comparative example are shown in Table 1. Table 1. Preparation conditions and test results of electrolytes in each example and comparative example. analyze: In Table 1, the average coulombic efficiency and cycle life of the aluminum batteries prepared in Examples 1-19 are greater than those in Comparative Examples 1-5, indicating that adding an appropriate amount of diluent to the mixed electrolyte can effectively reduce the viscosity of the electrolyte, which helps to improve the coulombic efficiency of the aluminum battery and can also improve the cycle life of the aluminum battery.

[0085] By comparing Example 1 with Comparative Example 1, comparing Examples 3 and 4 with Comparative Example 3, and comparing Example 12 with Comparative Example 4, it can be demonstrated that adding a diluent to the mixed electrolyte can effectively reduce the viscosity of the electrolyte, which helps to improve the coulombic efficiency of the aluminum battery and can improve the cycle life of the aluminum battery.

[0086] By comparing Example 1 with Comparative Example 2, it can be seen that excessive addition of diluent will result in a low concentration of active ions in the electrolyte, which is not conducive to improving the average coulombic efficiency of aluminum batteries.

[0087] By comparing Example 1 with Comparative Example 5, it can be concluded that excessive addition of aluminum salt will lead to excessively high content of active ions in the electrolyte and increased viscosity of the electrolyte, which in turn slows down the diffusion rate of conductive ions in the electrolyte and reduces the average coulombic efficiency of the aluminum battery.

[0088] Furthermore, to further investigate the effect of the diluent in the electrolyte on aluminum deposition, an electrochemical workstation was used at 3 mA / cm². 2 The current density was deposited at 0.1 mAh / cm² on the copper foils of Example 1 and Comparative Example 1, respectively. 2 and 3mAh / cm 2 Afterwards, the button cell was disassembled in an argon-protected glove box, and the surface of the copper foil was subjected to scanning tunneling microscopy.

[0089] Please see Figures 2 to 5 , Figure 2 The aluminum deposition rate in Example 1 was 0.1 mAh / cm³. 2 Scanning tunneling microscopy image of aluminum nucleation. Figure 3 The aluminum deposition in Example 1 was 3 mAh / cm². 2 Scanning tunneling microscope image, Figure 4 For Comparative Example 1, aluminum deposition was 0.1 mAh / cm³. 2 Scanning tunneling microscopy image of aluminum nucleation. Figure 5 For comparative example 1, aluminum deposition was 3 mAh / cm³. 2 Scanning tunneling microscope image.

[0090] Will Figure 2 and Figure 4 The comparison shows that when 0.1 mAh / cm³ is deposited... 2 Subsequently, the aluminum crystal nuclei in Example 1 were uniformly and densely distributed, while those in Comparative Example 1 were sparsely and unevenly distributed. Figure 3 and Figure 5 The comparison shows that when a deposition of 3mAh / cm³ is achieved... 2Subsequently, the aluminum crystal nuclei in Example 1 exhibited planar deposition, while those in Comparative Example 1 showed dendritic deposition. This demonstrates that adding benzene and its derivative diluents to the aluminum salt-functional additive electrolyte system can adjust the aluminum deposition pattern in the electrolyte, causing the aluminum deposition to form spherical crystal nuclei and grow along the plane, thus improving the morphology of the aluminum deposition.

[0091] Further, see Figure 5 and Figure 6 , Figure 5 and Figure 6 The aluminum batteries prepared in Example 1 and Comparative Example 1, respectively, have an efficiency of 1 mA / cm. 2 Current density and 10 mAh / cm 2 Long-cycle performance tests were conducted at the specified capacity. The results showed that, at room temperature, the aluminum battery of Example 1 could cycle for more than 130 cycles, with a cycle time exceeding 2600 hours and an average coulombic efficiency greater than 99.5%. In contrast, the aluminum battery of Comparative Example 1 had a cycle life of less than 50 hours, only 2 cycles. This demonstrates that adding benzene and its derivatives as diluents to the aluminum salt-functional additive electrolyte system can inhibit the growth of aluminum dendrites and improve the cycle life of the aluminum battery.

[0092] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an electrolyte, characterized in that, Includes the following steps: Aluminum salt, functional additives, and diluents are mixed evenly at a molar ratio of (1.1~5.1):1:(0.1~10) to obtain the electrolyte; wherein, The functional additive is a compound that can form an ionic liquid or a eutectic solvent with the aluminum salt, and the diluent includes one or more of benzene and its derivatives.

2. The preparation method according to claim 1, characterized in that, The structural formula of the benzene derivative is shown below: R1, R2, R3, R4, R5, and R6 are independently selected from any one of hydrogen atoms, halogen atoms, amino groups and their derivatives, C1-C6 alkyl groups and their derivatives, and C1-C6 alkoxy groups and their derivatives.

3. The preparation method according to claim 2, characterized in that, The benzene derivatives include one or more of toluene, propylbenzene, o-difluorobenzene, aniline-fluorobenzene, trifluoroaniline, m-difluorobenzene, p-difluorobenzene, trifluorobenzene, hexafluorobenzene, trifluoromethoxybenzene, and trifluoromethylbenzene.

4. The preparation method according to any one of claims 1-3, characterized in that, The functional additives include one or more of 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, acetamide, propionamide, N,N-dimethylacetamide, tetrabutylammonium chloride, pyridine and its derivatives, pyrrole and its derivatives, piperidine and its derivatives, urea, methylurea, and thiourea.

5. The preparation method according to any one of claims 1-3, characterized in that, The aluminum salt includes AlCl3.

6. The preparation method according to any one of claims 1-3, characterized in that, The aluminum salt, the functional additive, and the diluent are mixed evenly in a molar ratio of (1.1~1.7):1:(1~10).

7. An electrolyte, characterized in that, It is prepared by any one of the preparation methods described in claims 1-6.

8. The electrolyte as described in claim 7, characterized in that, The electrolyte contains active ions, including [Al₂Cl₇]. - and [AlCl4] - At least one of them.

9. A rechargeable aluminum battery, characterized in that, The electrolyte includes the electrolyte prepared by any one of the preparation methods described in claims 1-6, or the electrolyte described in any one of claims 7-8.

10. The rechargeable aluminum battery as described in claim 9, characterized in that, The aluminum battery also includes a positive electrode, a negative electrode, and a separator disposed between the positive electrode and the negative electrode, wherein the separator is a polyolefin separator or a glass fiber separator.

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