A eutectic aqueous aluminum-ion battery electrolyte, a preparation method and application thereof

Abstract

The application provides a eutectic aqueous aluminum ion battery electrolyte and a preparation method and application thereof, and relates to the technical field of aluminum ion batteries.The eutectic aqueous aluminum ion battery electrolyte is prepared by solid-solid mixing of aluminum metal salt and eutectic substance; the aluminum metal salt is selected from at least one of aluminum chloride hexahydrate, aluminum perchlorate nonahydrate, aluminum nitrate nonahydrate and aluminum sulfate octadecahydrate; and the eutectic substance is an organic small-molecule compound containing amino and ester groups. By screening and proportion control of the hydrated aluminum metal salt and the eutectic substance, the prepared electrolyte is applied to an aqueous aluminum ion battery, such as a symmetrical battery and a full battery, and excellent performance is exhibited. The electrolyte can improve the stability of the aluminum ion battery, form an anion-dominated solvation structure, and at the same time, form a dense anion-rich solid electrolyte interface layer on the surface of the aluminum negative electrode to protect the aluminum metal negative electrode. The problem of poor negative electrode stability of the existing aqueous aluminum ion battery is solved.

Description

Technical Field

[0001] This invention relates to the field of aluminum-ion battery technology, and in particular to a eutectic aqueous aluminum-ion battery electrolyte, its preparation method, and its application. Background Technology

[0002] To address the energy shortages and environmental pollution crises caused by the overconsumption of traditional fossil fuels, the world urgently needs to shift towards renewable energy sources such as solar, wind, biomass, hydroelectric, and geothermal energy. These clean energy sources have vast potential, but their power generation is intermittent and unstable due to temporal and spatial variations and geographical conditions. Therefore, how to effectively store this unstable electricity and ensure its stable grid dispatch has become a pressing issue. While traditional mechanical energy storage systems such as pumped hydro storage, gravity storage, and compressed air storage are widely used, they are limited by geographical conditions and the environment, have high installation and maintenance costs, and require large land areas, making them difficult to popularize in diverse application scenarios. Therefore, electrochemical energy storage systems, as a novel energy storage technology, have shown great potential. Compared to traditional mechanical energy storage methods, electrochemical energy storage systems are not limited by environmental conditions such as terrain and climate, and can be flexibly deployed in different regions and scenarios, demonstrating strong adaptability. Electrochemical energy storage systems can store more energy in a smaller volume and weight, making them particularly suitable for applications with high space requirements, such as portable electronic devices and wearable devices. Electrochemical energy storage systems have high power output and can respond instantly to grid fluctuations or load demands, ensuring grid stability. Electrochemical energy storage systems can meet energy demands of different scales, from small household energy storage devices to large-scale grid energy storage, and are an important component of future energy infrastructure.

[0003] Although electrochemical energy storage systems currently face challenges such as high cost, limited lifespan, and low cycle efficiency, continuous technological innovation, particularly driven by the development of new materials, improvements in manufacturing processes, and large-scale industrial production, promises to achieve lower costs, higher performance, and longer lifespans in the future. This opens up broad prospects for a variety of applications, from small portable devices to large-scale stationary energy storage systems. By continuously advancing electrochemical energy storage technology, we can achieve more efficient energy utilization in the future, further promoting the transformation of the global energy structure and the development of a green and low-carbon economy.

[0004] Research has found that aqueous aluminum-ion batteries can fully meet the requirements of large-scale energy storage systems. Due to the abundance and excellent safety of aluminum, aluminum-ion batteries have significant potential. Furthermore, as a multivalent metal, aluminum can provide a higher volumetric capacity than lithium batteries (aluminum: 8046 mAh / cm³). 3 Lithium: 2045mAh / cm³ 3Therefore, aluminum-ion batteries are expected to be more compact than lithium-ion batteries in terms of size, an advantage that is particularly significant in space-constrained applications. Aluminum has a specific capacity of 2980 mAh / g, slightly lower than lithium's 3860 mAh / g, but still higher than many other metals (such as sodium, potassium, magnesium, and calcium). Due to aluminum's higher specific capacity and volumetric capacity, the overall energy density of aluminum-ion battery systems may approach or even exceed that of lithium-ion batteries. This characteristic makes aluminum-ion batteries show great potential in applications requiring high energy density. Compared to traditional lithium-ion batteries, the advantages of aluminum-ion batteries are not only reflected in the abundance and low cost of the material, but also in the significantly superior safety of aluminum. Lithium-ion batteries suffer from safety hazards such as overcharging, short circuits, and thermal runaway, while aluminum batteries have better thermal stability and are less prone to fire or explosion, thus providing higher safety under high-temperature or extreme environmental conditions. In addition to safety and cost advantages, the long-cycle stability and faster charge / discharge speed of aluminum-ion batteries are also potential advantages. With advancements in battery technology, the cycle life and efficiency of aluminum-ion batteries are expected to improve further, enabling them to meet the needs of diverse applications, from small portable devices to large-scale grid energy storage systems. In summary, aluminum-ion batteries, with their low cost, high safety, high energy density, and excellent overall performance, are poised to become an important supplement to current energy storage battery systems. With continuous technological innovation, aluminum-ion batteries have the potential to become a crucial component of future energy storage solutions, particularly in large-scale energy storage, electric vehicles, and renewable energy storage, where they will play a significant role.

[0005] In aluminum ion electrolytes with water as the main solvent, the standard electrode potential of aluminum is -1.66V (relative to the standard hydrogen electrode), which is relatively low. According to electrochemical principles, when aluminum is in an electrolyte with water as the main solvent, it reacts more readily with water to produce hydrogen gas (H2) and aluminum hydroxide (Al(OH)3), among other products. This makes the electrochemical behavior of aluminum unstable, especially during charging, where oxidation easily occurs at the aluminum anode rather than the deposition of metallic aluminum on its surface. However, in ionic liquid electrolytes primarily composed of AlCl3 / [EMIm]Cl, the carrier ions are Al3... + It becomes AlCl4 - and Al2Cl7 - The three-electron transfer reaction of aluminum is difficult to achieve, resulting in a relatively low actual energy density. Furthermore, the unavoidable corrosion in chlorine-based electrolytes severely shortens the lifespan of the aluminum metal anode, and the air sensitivity of ionic liquids further increases the difficulty of electrolyte storage. These factors hinder the commercial application of aluminum-ion batteries. Therefore, it is necessary to explore a novel aqueous aluminum-ion electrolyte that is low-cost, air-stable, and provides protection for the aluminum anode. In view of this, the present invention is proposed. Summary of the Invention

[0006] This invention provides a eutectic aqueous aluminum-ion battery electrolyte, its preparation method, and its application, with the aim of solving the problem of poor anode stability in existing aqueous aluminum-ion batteries.

[0007] To achieve the above objectives, embodiments of the present invention provide a eutectic aqueous aluminum-ion battery electrolyte, its preparation method, and its application. The eutectic electrolyte of the present invention is prepared by solid-solid miscibility of an aluminum metal salt and a eutectic substance. The aluminum metal salt is selected from at least one of aluminum chloride hexahydrate, aluminum perchlorate nonahydrate, aluminum nitrate nonahydrate, and aluminum sulfate octadecahydrate; the eutectic substance is selected from ester compounds. The molar ratio of the aluminum metal salt to a single ester compound is 1:1-8, and the molar ratio of the aluminum metal salt to two ester compounds is 1:2:2. Through screening and ratio control of hydrated aluminum metal salts and ester compounds, the prepared preferred electrolyte exhibits excellent performance in both symmetrical and full-cell batteries. The present invention also includes the electrolyte prepared by the aforementioned method and its application in aqueous aluminum-ion batteries. The electrolyte of the present invention can improve the stability of aluminum-ion batteries, forming a solvation structure dominated by anions, while simultaneously forming a dense anion-rich solid electrolyte interphase (SEI) layer on the surface of the aluminum anode to protect the aluminum metal anode.

[0008] An embodiment of the present invention provides a eutectic aqueous aluminum-ion battery electrolyte, the aqueous aluminum-ion battery electrolyte comprising an aluminum metal salt and a eutectic substance;

[0009] The aluminum metal salt includes at least one of aluminum chloride hexahydrate, aluminum perchlorate nonahydrate, aluminum nitrate nonahydrate, and aluminum sulfate octadecahydrate;

[0010] The eutectic material is a small organic molecule compound containing amino and ester groups.

[0011] Preferably, the eutectic material is selected from methyl carbamate or ethyl carbamate; the molar ratio of aluminum metal salt to eutectic material is 1:1 to 8.

[0012] Preferably, the eutectic material is selected from methyl carbamate and ethyl carbamate.

[0013] More preferably, the molar ratio of the aluminum metal salt, methyl carbamate, and ethyl carbamate is 1:2:2.

[0014] Based on a general inventive concept, embodiments of the present invention provide a method for preparing a eutectic aqueous aluminum-ion battery electrolyte, wherein an aluminum metal salt is mixed with a eutectic substance to prepare the aqueous aluminum-ion battery electrolyte.

[0015] Preferably, the mixing process is as follows: heating at 30–90°C for 10–40 minutes, naturally cooling to room temperature, and then stirring for 10–30 minutes. More preferably, the heating temperature is 30–50°C; stirring for 10 minutes.

[0016] Embodiments of the present invention also provide an aqueous aluminum-ion secondary battery, comprising the above-described eutectic aqueous aluminum-ion battery electrolyte or the eutectic aqueous aluminum-ion battery electrolyte prepared by the above-described preparation method.

[0017] Preferably, the aqueous aluminum-ion secondary battery is a symmetrical battery composed of aluminum foil, a glass fiber membrane, and an aqueous aluminum-ion battery electrolyte.

[0018] Preferably, the aqueous aluminum-ion secondary battery is a full battery composed of aluminum foil as the negative electrode, positive electrode, glass fiber separator, and aqueous aluminum-ion battery electrolyte.

[0019] More preferably, the positive electrode material is selected from at least one of manganese dioxide, Prussian blue, polyaniline, activated carbon, and diquinoxolino[2,3-A:2',3'-C]phenazine.

[0020] The aluminum foil, referred to simply as aluminum foil, has no particular thickness requirement, as long as it meets the requirements for aluminum foil negative electrode applications. For example, it should be greater than or equal to 35 μm, preferably greater than or equal to 50 μm, more preferably 50–300 μm, and even more preferably 50–200 μm. The aluminum foil undergoes pretreatment, including polishing and / or cleaning.

[0021] mechanism

[0022] This invention, through screening and optimizing the proportions of hydrated aluminum metal salts and ester compounds, produces a low-eutectic aqueous aluminum-ion battery electrolyte with advantages such as low cost, air stability, and protection of the aluminum anode. The electrolyte of this invention improves the stability of aluminum-ion batteries, forming a solvation structure dominated by anions, while simultaneously forming a dense, anion-rich solid electrolyte interface layer on the aluminum anode surface to protect the aluminum metal anode. This solves the problem of poor anode stability in existing aqueous aluminum-ion batteries. As an electrolyte for aqueous aluminum-ion batteries, the low-eutectic aqueous aluminum-ion battery electrolyte of this invention can significantly improve battery cycle life and stability, and continuously protect the metal anode.

[0023] The above-described solution of the present invention has the following beneficial effects:

[0024] (1) The present invention uses hydrated aluminum metal salt and ester compound to make miscible, and selects a low-cost, air-stable electrolyte that can protect the aluminum metal negative electrode by screening the ratio of hydrated aluminum metal salt and ester compound.

[0025] (2) The hydrated eutectic electrolyte obtained in this invention is used in aqueous aluminum-ion battery electrolytes to achieve excellent electrochemical performance. This alleviates the instability of traditional aqueous electrolytes and their corrosion of the aluminum metal anode.

[0026] (3) The process of this invention is simple and low-cost, and it is easy to achieve large-scale industrial production. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments 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.

[0028] Figure 1 This is the electrolyte of Example 1 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0029] Figure 2 This is the electrolyte of Example 2 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0030] Figure 3 This is the electrolyte of Example 3 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0031] Figure 4 This is the electrolyte of Comparative Example 1 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0032] Figure 5 This is the electrolyte of Comparative Example 2 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0033] Figure 6 This is the electrolyte of Comparative Example 3 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0034] Figure 7 This is the electrolyte of Comparative Example 4 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0035] Figure 8 This is the electrolyte of Comparative Example 5 of the present invention, with aluminum foil as the negative electrode, at 0.5 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0036] Figure 9 These are scanning electron microscope images of the electrolytes used in Examples 1-3 and Comparative Examples 1-5 of the present invention, with aluminum foil as the negative electrode, after symmetrical battery cycling.

[0037] Figure 10 This is the electrolyte of Example 1 of the present invention, with aluminum foil as the negative electrode, at 0.2 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0038] Figure 11 This is the electrolyte of Comparative Example 5 of the present invention, with aluminum foil as the negative electrode, at 0.2 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0039] Figure 12 This is the electrolyte of Comparative Example 6 of the present invention, with aluminum foil as the negative electrode, at 0.2 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0040] Figure 13 This is the electrolyte of Comparative Example 7 of the present invention, with aluminum foil as the negative electrode, at 0.2 mA / cm. 2 Cyclic charge-discharge curves of a symmetrical battery at current density.

[0041] Figure 14 These are the electrolytes of Embodiment 1 and Comparative Example 5 of the present invention, with aluminum foil as the negative electrode, and XPS images of the aluminum foil surface after symmetrical battery cycling.

[0042] Figure 15 The images shown are scanning electron microscope images and optical images of the aluminum foil surface after immersion at different temperatures using the electrolytes of Embodiment 1 and Comparative Example 5 of the present invention.

[0043] Figure 16 This is the electrolyte of Example 1 of the present invention, with aluminum foil as the negative electrode and polyaniline as the positive electrode, and its cycling performance at a current density of 500 mA / g.

[0044] Figure 17 This is a diagram showing the cycling performance of the electrolyte of Comparative Example 6 of the present invention, with aluminum foil as the negative electrode and polyaniline as the positive electrode, at a current density of 500 mA / g.

[0045] Figure 18 This is the electrolyte of Comparative Example 7 of the present invention, with aluminum foil as the negative electrode and polyaniline as the positive electrode, and its cycling performance at a current density of 500 mA / g.

[0046] Figure 19 The figures show the cyclic charge-discharge curves of the electrolytes used in Examples 1 and 6-7 of this invention, with aluminum foil as the negative electrode and diquinoxalino[2,3-A:2',3'-C]phenazine as the positive electrode.

[0047] Figure 20 These are optical images of the electrolytes under different aluminum salts in Embodiment 1 and Comparative Example 8 of the present invention. Detailed Implementation

[0048] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0049] 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.

[0050] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0051] To address the problem of poor stability of the negative electrode in existing aqueous aluminum-ion batteries, embodiments of the present invention provide a eutectic aqueous aluminum-ion battery electrolyte, wherein the aqueous aluminum-ion battery electrolyte comprises aluminum metal salt and eutectic material;

[0052] The aluminum metal salt includes at least one of aluminum chloride hexahydrate, aluminum perchlorate nonahydrate, aluminum nitrate nonahydrate, and aluminum sulfate octadecahydrate;

[0053] The eutectic material is a small organic molecule compound containing amino and ester groups.

[0054] Preferably, the eutectic material is selected from methyl carbamate or ethyl carbamate; the molar ratio of aluminum metal salt to eutectic material is 1:1 to 8.

[0055] Preferably, the eutectic material is selected from methyl carbamate and ethyl carbamate.

[0056] More preferably, the molar ratio of the aluminum metal salt, methyl carbamate, and ethyl carbamate is 1:2:2.

[0057] Based on a general inventive concept, embodiments of the present invention provide a method for preparing a eutectic aqueous aluminum-ion battery electrolyte, wherein an aluminum metal salt is mixed with a eutectic substance to prepare the aqueous aluminum-ion battery electrolyte.

[0058] Preferably, the mixing process is as follows: heating at 30–90°C for 10–40 minutes, naturally cooling to room temperature, and then stirring for 10–30 minutes. More preferably, the heating temperature is 30–50°C; stirring for 10 minutes.

[0059] Embodiments of the present invention also provide an aqueous aluminum-ion secondary battery, comprising the above-described eutectic aqueous aluminum-ion battery electrolyte or the eutectic aqueous aluminum-ion battery electrolyte prepared by the above-described preparation method.

[0060] Preferably, the aqueous aluminum-ion secondary battery is a symmetrical battery composed of aluminum foil, a glass fiber membrane, and an aqueous aluminum-ion battery electrolyte.

[0061] Preferably, the aqueous aluminum-ion secondary battery is a full battery composed of aluminum foil as the negative electrode, positive electrode, glass fiber separator, and aqueous aluminum-ion battery electrolyte.

[0062] More preferably, the positive electrode material is selected from at least one of manganese dioxide, Prussian blue, polyaniline, activated carbon, and diquinoxolino[2,3-A:2',3'-C]phenazine.

[0063] The aluminum foil, referred to simply as aluminum foil, has no particular thickness requirement, as long as it meets the requirements for aluminum foil negative electrode applications. For example, it should be greater than or equal to 35 μm, preferably greater than or equal to 50 μm, more preferably 50–300 μm, and even more preferably 50–200 μm. The aluminum foil undergoes pretreatment, including polishing and / or cleaning.

[0064] The following description is based on specific examples.

[0065] Example 1

[0066] This embodiment provides a method for preparing a eutectic aqueous aluminum-ion battery electrolyte.

[0067] The method includes the following steps:

[0068] Weigh aluminum perchlorate nonahydrate and methyl carbamate in a 1:4 molar ratio.

[0069] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0070] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0071] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0072] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, with aluminum foil as the negative electrode and polyaniline or diquinoxolino[2,3-A:2',3'-C]phenazine as the positive electrode, and a full cell was assembled.

[0073] Example 2

[0074] This embodiment provides a method for preparing a eutectic aqueous aluminum-ion battery electrolyte.

[0075] The method includes the following steps:

[0076] Weigh aluminum perchlorate nonahydrate and ethyl carbamate in a 1:4 molar ratio.

[0077] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0078] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0079] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0080] Example 3

[0081] This embodiment provides a method for preparing a eutectic aqueous aluminum-ion battery electrolyte.

[0082] The method includes the following steps:

[0083] Weigh aluminum perchlorate nonahydrate, methyl carbamate, and ethyl carbamate in a molar ratio of 1:2:2.

[0084] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0085] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0086] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing an aluminum-ion battery electrolyte.

[0089] The method includes the following steps:

[0090] Weigh aluminum perchlorate nonahydrate and methyl acrylate in a 1:4 molar ratio.

[0091] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0092] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0093] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0094] Comparative Example 2

[0095] This comparative example provides a method for preparing an aluminum-ion battery electrolyte.

[0096] The method includes the following steps:

[0097] Weigh aluminum perchlorate nonahydrate and ethyl acrylate in a 1:4 molar ratio.

[0098] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0099] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0100] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0101] Comparative Example 3

[0102] This comparative example provides a method for preparing an aluminum-ion battery electrolyte.

[0103] The method includes the following steps:

[0104] Weigh aluminum perchlorate nonahydrate, methyl carbamate, and ethyl acrylate in a molar ratio of 1:2:2.

[0105] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0106] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0107] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0108] Comparative Example 4

[0109] This comparative example provides a method for preparing an aluminum-ion battery electrolyte.

[0110] The method includes the following steps:

[0111] Weigh aluminum perchlorate nonahydrate, methyl acrylate, and ethyl acrylate in a molar ratio of 1:2:2.

[0112] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 50°C to obtain a clear solution.

[0113] The clear solution obtained in step (2) was allowed to cool naturally to room temperature, and then stirred at room temperature for 10 minutes to obtain a clear and transparent electrolyte at room temperature.

[0114] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0115] Comparative Example 5

[0116] Similar to Example 1, the aluminum metal salt is aluminum perchlorate nonahydrate, the difference being that no eutectic substances are added, and water is used as the main solvent to prepare an aluminum perchlorate electrolyte with a molar concentration of 1M.

[0117] Mix the weighed substances from step (1) into a 25 mL serum bottle, place a suitable magnetic ball in the bottle, and then stir at 500 rpm for 10 minutes at 30°C to obtain a clear solution.

[0118] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0119] Comparative Example 6

[0120] Compared with Example 1, the only difference is that the ratio of aluminum perchlorate nonahydrate to methyl carbamate is changed to 1:6, and all other operations and parameters are the same as in Example 1.

[0121] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0122] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, with aluminum foil as the negative electrode and polyaniline or diquinoxolino[2,3-A:2',3'-C]phenazine as the positive electrode, and a full cell was assembled.

[0123] Comparative Example 7

[0124] Compared with Example 1, the only difference is that the ratio of aluminum perchlorate nonahydrate to methyl carbamate is changed to 1:8, and all other operations and parameters are the same as in Example 1.

[0125] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, and aluminum foil was used as the negative electrode to assemble a symmetrical battery.

[0126] The prepared electrolyte was used as the electrolyte for an aluminum metal ion battery, with aluminum foil as the negative electrode and polyaniline or diquinoxolino[2,3-A:2',3'-C]phenazine as the positive electrode, and a full cell was assembled.

[0127] Comparative Example 8

[0128] Compared to Example 1, the difference lies in modifying the aluminum metal salt from aluminum perchlorate nonahydrate to the following:

[0129] Group A: Aluminum chloride hexahydrate;

[0130] Group B: Aluminum nitrate nonahydrate;

[0131] Group C: Aluminum sulfate octadecahydrate.

[0132] Stir at 50°C for 10 minutes, then cool to room temperature and stir for another 10 minutes.

[0133] like Figure 20 As shown, after cooling, only the electrolyte formed by aluminum perchlorate nonahydrate and the eutectic material remains clear, making aluminum perchlorate nonahydrate a preferred aluminum metal salt.

[0134] Application Example 1

[0135] The electrolytes obtained in Examples 1-3 and Comparative Examples 1-5 were used to assemble symmetrical cells with glass fiber as the separator and aluminum foil as the negative electrode. The electrochemical performance was tested using a Newway battery testing system under the following conditions: current density 0.5 mA / cm². 2 The charging and discharging time is 1 hour, and the temperature is 30℃.

[0136] Table 1 Cycle Life Data for Symmetrical Batteries

[0137] Cycle life (h) Example 1 138 Example 2 124 Example 3 85 Comparative Example 1 62 Comparative Example 2 42 Comparative Example 3 73 Comparative Example 4 66 Comparative Example 5 75

[0138] Table 1 shows that the symmetrical battery assembled in Example 1 has the longest cycle life. Meanwhile, through... Figure 9Scanning electron microscope images show that the aluminum foil surface after the cycle in Example 1 is smoother and more orderly. This is because the weaker binding of methyl carbamate with aluminum ions in the electrolyte leads to the formation of a solvation structure dominated by anions. Its faster kinetic behavior plays a key role in the uniformity of deposition and peeling. Secondly, the adsorption and decomposition of methyl carbamate and perchlorate on the aluminum surface can form a solid electrolyte film rich in perchlorate. This film can accelerate ion transport while protecting the aluminum anode from water corrosion.

[0139] Application Example 2

[0140] The electrolytes obtained in Examples 1 and 5-7 were used to assemble symmetrical cells with glass fiber as the separator and aluminum foil as the negative electrode. The electrochemical performance was tested using a Newway battery testing system under the following conditions: current density 0.2 mA / cm². 2 The charging and discharging time is 1 hour, and the temperature is 30℃.

[0141] Table 2 Cycle Life Data for Symmetrical Batteries

[0142] Cycle life (h) Example 1 600 Comparative Example 5 130 Comparative Example 6 225 Comparative Example 7 235

[0143] As can be seen from Table 2, the symmetrical battery assembled in Example 1 has the longest cycle life. By optimizing the ratio of aluminum metal salt to methyl carbamate, it can be determined that Example 1 has the preferred ratio. Meanwhile, through... Figure 14 XPS analysis showed that, compared to Comparative Example 5, the aluminum foil surface after cycling in Example 1 exhibited perchlorate and nitrogen signals. This indicates the formation of a dense, anion-rich solid electrolyte layer (SEI), which prevented the reaction between water and aluminum, demonstrating its protective effect on the aluminum anode. Figure 15 The scanning electron microscope and optical images show that the aluminum foil immersed in Example 1 at different temperatures exhibited less corrosion compared to Comparative Example 5. This is because the adsorption of methyl carbamate on the aluminum surface prevented further reaction between aluminum and water.

[0144] Application Example 3

[0145] The electrolytes obtained in Examples 1 and Comparative Examples 6-7 were used with glass fiber as the separator, aluminum foil as the negative electrode, and polyaniline or diquinoxalino[2,3-A:2',3'-C]phenazine as the positive electrode. Electrochemical performance was tested using a Newway battery testing system. When the positive electrode was polyaniline, the test conditions were a current density of 500 mA / g, a voltage range of 0.4V-1.5V, and a temperature of 30℃; when the positive electrode was diquinoxalino[2,3-A:2',3'-C]phenazine, the test conditions were a current density of 100 mA / g, a voltage range of 0.3V-1.5V, and a temperature of 30℃.

[0146] pass Figures 16-18 It can be concluded that, using aluminum foil as the negative electrode and polyaniline as the positive electrode, the full battery assembled with the electrolyte in Example 1 exhibits a longer cycle life and specific capacity (800 cycles and specific capacity >130mAh / g). Figure 19 It can be concluded that when aluminum foil is used as the negative electrode and diquinoxalino[2,3-A:2',3'-C]phenazine as the positive electrode, the full cell assembled with the electrolyte in Example 1 exhibits less polarization and a higher specific capacity (309 mAh / g). Therefore, it can be demonstrated that Example 1 performs better and is the preferred ratio.

[0147] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low eutectic aqueous aluminum-ion battery electrolyte, characterized in that, The aqueous aluminum ion battery electrolyte comprises an aluminum metal salt and a eutectic substance; The aluminum metal salt comprises at least one of aluminum chloride hexahydrate, aluminum perchlorate nonahydrate, aluminum nitrate nonahydrate and aluminum sulfate octadecahydrate; The eutectic substance is an organic small-molecule compound containing amino and ester groups; the eutectic substance is selected from methyl and / or ethyl carbamate; the molar ratio of the aluminum metal salt to the eutectic substance is 1:

4.

2. The eutectic aqueous aluminum-ion battery electrolyte of claim 1, wherein, The eutectic substance is selected from methyl and ethyl carbamate.

3. The eutectic aqueous aluminum-ion battery electrolyte of claim 2, wherein, The molar ratio of the aluminum metal salt, methyl carbamate and ethyl carbamate is 1:2:

2.

4. The method for preparing a eutectic aqueous electrolyte for aluminum ion batteries according to any one of claims 1 to 3, characterized in that, The aluminum metal salt and the eutectic substance are mixed to prepare the aqueous aluminum ion battery electrolyte.

5. The preparation method according to claim 4, characterized in that, The mixing process is: heating at 30-90 ℃ for 10-40 min, then stirring for 10-30 min after natural cooling to room temperature.

6. An aqueous aluminum-ion secondary battery, characterized by, The aqueous aluminum ion battery electrolyte comprises an aluminum metal salt and a eutectic substance.

7. The aqueous aluminum-ion secondary battery according to claim 6, wherein The aqueous aluminum ion secondary battery is a symmetric battery composed of an aluminum metal foil, a glass fiber separator and the aqueous aluminum ion battery electrolyte.

8. The aqueous aluminum-ion secondary battery of claim 6, wherein, The aqueous aluminum ion secondary battery is a full battery composed of an aluminum metal foil as a negative electrode, a positive electrode, a glass fiber separator and the aqueous aluminum ion battery electrolyte.

9. The aqueous aluminum-ion secondary battery of claim 8, wherein, The positive electrode material is selected from at least one of manganese dioxide, Prussian blue, polyaniline, activated carbon and diquinoxalamine [2,3-A:2',3'-C] phenazine.

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