Aluminum ion battery positive electrode material, aluminum ion battery positive electrode and aluminum ion battery

Abstract

The invention provides an aluminum ion battery positive electrode material. The aluminum ion battery positive electrode material comprises a carbon material, a binder and nitryl indole salt. Meanwhile, the invention also provides an aluminum ion battery positive electrode comprising the aluminum ion battery positive electrode material, and an aluminum ion battery comprising the aluminum ion battery positive electrode.

Description

Technical Field

[0001] The present invention relates to a novel aluminum ion energy storage battery, in particular to a positive electrode material comprising a nitroindole salt, an aluminum ion battery positive electrode comprising the positive electrode material of the nitroindole salt, and an aluminum ion battery comprising the aluminum ion battery positive electrode. Background Art

[0002] Aluminum-ion batteries are a type of rechargeable battery. During discharge, aluminum ions move from the cathode to the anode; during charging, the aluminum ions return to the cathode. Aluminum-ion batteries function similarly to lithium-ion batteries, but their energy output differs due to differences in composition and structure. Aluminum-ion batteries can be fully charged in a very short time and can be recharged 7,500 times.

[0003] The main drawback of aluminum-ion batteries is that they require ionic liquids as electrolytes, which are inherently expensive and corrosive, making them difficult to commercialize. Furthermore, aluminum-ion batteries exhibit an unstable discharge plateau and rapid capacity decay, primarily due to volume expansion of the cathode material, dissolution of the active material, and electrolyte side reactions.

[0004] Patent application number CN104810544A discloses a rechargeable aluminum ion battery and its preparation method. The resulting battery can operate independently or multiple batteries can be connected in series or parallel to form a battery pack for practical application.

[0005] Patent application number CN106410201A discloses an aluminum-ion battery negative electrode material, its preparation method, and its application. Due to the adoption of the aforementioned technical solution, electrochemical performance testing has shown that the battery negative electrode material, carbon material, and its composites herein have excellent stability and conductivity, which can improve the specific capacity, cycle performance, and service life of aluminum-ion batteries. Furthermore, the preparation method is simple, the raw materials are abundant, and the cost is low, making it highly promising as a practical aluminum-ion battery negative electrode material. The first-cycle discharge specific capacity is as high as approximately 88 mAh / g, with a discharge platform of 2.0V. Furthermore, the material exhibits good cycle performance, with a remaining specific capacity of 70 to 80 mAh / g after 100 cycles.

[0006] Patent application number CN118554017A discloses an aluminum-based organic electrolyte and its applications. Compared to the prior art, where the overpotential for aluminum plating in organic solutions is generally >500mV, the aluminum-based organic electrolyte in this invention is capable of achieving highly reversible aluminum anode deposition and dissolution reactions at a lower overpotential. Notably, the invention implements an electrochemical desolvation reaction mechanism based on active aluminum cationic species, providing the necessary conditions for constructing aluminum-based electrochemical energy storage devices based on organic electrolytes. More importantly, the special solvation between the weak Lewis alkaline solvent and the aluminum salt in this invention prevents the aluminum-based organic electrolyte from corroding the metal current collector and battery casing, significantly reducing the cost of aluminum batteries.

[0007] Patent application CN105810947A discloses an aluminum-ion battery cathode material, electrode, and aluminum-ion battery. The aluminum-ion battery in this invention utilizes a composite carbon material with a three-dimensional cross-linked carbon skeleton as the cathode. This improves the efficiency of aluminum ion insertion and extraction within the cathode, thereby increasing the battery's charge and discharge efficiency. This also facilitates high-rate charge and discharge, improving the battery's cycle performance. Summary of the Invention

[0008] The first object of the present invention is to provide an aluminum ion battery positive electrode material comprising a nitroindole salt, so as to solve the problems of unstable discharge platform and rapid capacity decay in existing aluminum ion batteries.

[0009] The second object of the present invention is to provide an aluminum ion battery positive electrode comprising the aluminum ion battery positive electrode material.

[0010] The third object of the present invention is to provide an aluminum ion battery comprising the aluminum ion battery positive electrode.

[0011] The present invention can be achieved through the following technical solutions:

[0012] A positive electrode material for an aluminum ion battery, comprising a carbon material, a binder and a nitroindole salt;

[0013] The structure of the nitro indole salt is as follows:

[0014]

[0015] The mass ratio of the carbon material, the binder and the nitroindole salt is 7:2:1.

[0016] The carbon material includes carbon black.

[0017] The binder includes polyvinylidene fluoride

[0018] The synthesis method of the nitro indole salt comprises the following steps:

[0019] 4-Nitrophenylhydrazine and 3-methyl-2-butanone were mixed in a first organic solvent under a protective atmosphere and then heated under reflux to obtain

[0020] Will and iodoethane are dissolved in a second organic solvent under a protective atmosphere, mixed and heated under reflux to obtain the product.

[0021] The protective atmosphere includes nitrogen, argon or helium;

[0022] The first organic solvent comprises a mixed solution of acetic acid and ethanol;

[0023] The second organic solvent includes acetonitrile.

[0024] An aluminum ion battery positive electrode comprises the aluminum ion battery positive electrode material.

[0025] An aluminum ion battery comprises the aluminum ion battery positive electrode.

[0026] The aluminum ion battery also includes an [EMIm]Cl electrolyte.

[0027] The aluminum ion battery also includes a Whatman GF / C separator.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] This solves the problems of unstable discharge platform and rapid capacity decay in the prior art.

[0030] The aluminum ion positive electrode material provided by the present invention contains a nitroindole salt. Through reasonable molecular design, the material has an ultra-flat discharge platform and excellent electrochemical performance during the charge and discharge process.

[0031] The aluminum ion battery provided by the present invention exhibits excellent electrochemical performance during the charge and discharge process. Its energy density, cycle stability, and rate capability are significantly improved. Therefore, this aluminum ion battery has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 a shows the SEM image of the nitroindole salt material prepared in Example 1.

[0033] Figure 1 b shows the rate performance diagram of the aluminum ion battery prepared in Example 2.

[0034] Figure 1 c shows the charge and discharge curves of the aluminum ion battery prepared in Example 2 at different current densities.

[0035] Figure 1 d shows the long cycle curve and coulombic efficiency curve of the aluminum ion battery prepared in Example 2. DETAILED DESCRIPTION

[0036] The present invention provides an aluminum ion battery positive electrode material, which specifically includes a carbon material, a binder and a nitroindole salt; the structure of the nitroindole salt is as follows:

[0037]

[0038] The principle of nitroindole salt compounds as positive electrode materials for aluminum ion batteries is based on their unique n-type dual redox site mechanism. This mechanism enables nitroindole salt compounds to efficiently insert and remove aluminum ions during the charge and discharge process. The specific reaction is as follows:

[0039] Nitro group as redox site:

[0040]

[0041] Charging process: Nitro group (-NO2) receives two electrons, while aluminum ion (AlCl2 + ) are embedded into the positive electrode material from the electrolyte.

[0042] Discharge process: lose two electrons and return to nitro group (-NO2), while aluminum ion (AlCl2 + ) is deintercalated from the positive electrode material and returned to the electrolyte.

[0043] Iminium salts as redox sites:

[0044]

[0045] Charging process: the imine functional group receives two electrons, and the aluminum ion (AlCl2 + ) are embedded into the positive electrode material from the electrolyte.

[0046] Discharge process: lose two electrons to return to the imine bond, and at the same time the aluminum ion (AlCl2 + ) is deintercalated from the positive electrode material and returned to the electrolyte.

[0047] This dual redox site mechanism enables the nitroindole salt compound to exhibit high reversibility and stability during charge and discharge. Therefore, batteries using this nitroindole salt can have a long cycle life and high energy density.

[0048] As an electron-withdrawing group, nitro (-NO2) has the following advantages:

[0049] Strong electron-withdrawing effect: The nitro group can significantly reduce the electron density of the indole ring and enhance its redox activity, thereby improving the capacity and rate performance of the battery.

[0050] Reversible redox reaction: The nitro group participates in the entire redox process and is an important redox site, ensuring the long-cycle stability of the battery.

[0051] Structural stability: Nitroindole salt compounds exhibit high structural stability during the charge and discharge process, reducing material degradation and capacity attenuation.

[0052] Specifically, the mass ratio of the carbon material, the binder, and the nitroindole salt is 7:2:1. Those skilled in the art will appreciate that the present invention can also be implemented using similar mass ratios.

[0053] Specifically, the carbon material can be various conductive carbon materials, such as carbon black.

[0054] Specifically, the binder may be polyvinylidene fluoride or other types of organic binders.

[0055] Specifically, the synthesis method of the nitroindole salt comprises the following steps:

[0056] 4-Nitrophenylhydrazine and 3-methyl-2-butanone were mixed in a first organic solvent under a protective atmosphere and then heated under reflux to obtain

[0057] Will and ethyl iodide are dissolved in a protective atmosphere, mixed in a second organic solvent, and then heated under reflux to obtain the product. The protective atmosphere may be nitrogen or an inert gas such as argon or helium;

[0058] Specifically, the first organic solvent may be a mixed solution of acetic acid and ethanol;

[0059] Specifically, the second organic solvent may be acetonitrile.

[0060] Specifically, the present invention also provides an aluminum ion battery positive electrode, comprising the aluminum ion battery positive electrode material.

[0061] The present invention also provides an aluminum ion battery, including the aluminum ion battery positive electrode. Because the positive electrode of the aluminum ion battery contains a nitroindole salt compound, its unique redox reaction mechanism enables efficient aluminum ion insertion and extraction, significantly improving the battery's energy density. Moreover, the nitroindole salt compound exhibits an ultra-flat discharge platform during the charge and discharge process, ensuring stable output of the battery at different current densities. The battery containing the nitroindole salt compound exhibited extremely high capacity retention in long-cycle tests, maintaining a specific capacity of nearly 100 mAh / g after 800 cycles, and maintaining a high capacity at different current densities, demonstrating excellent rate performance.

[0062] Specifically, the aluminum ion battery further includes [EMIm]Cl electrolyte.

[0063] Specifically, the aluminum ion battery further includes a Whatman GF / C separator.

[0064] Example 1

[0065] Material synthesis:

[0066]

[0067] 100 g of 4-nitrophenylhydrazine (Compound 1) was added to a 500 ml three-necked flask equipped with an overhead stirrer and a nitrogen inlet and outlet, followed by a 250 ml mixed solution of acetic acid / ethanol (1:1) and 40 g of 3-methyl-2-butanone, and the mixture was heated under reflux overnight. After cooling to room temperature, the resulting solid was filtered and extracted with ethyl acetate. The combined organic layer was dried over anhydrous magnesium sulfate, the solvent was removed, and the residue was purified by silica gel column chromatography to obtain a brown oily compound 2 in a yield of 76%. 10 g of compound 2 and 14 g of iodoethane were dissolved in 100 ml of acetonitrile and refluxed under nitrogen for 12 hours. The reaction mixture was cooled to room temperature, filtered to obtain a red precipitate, and washed three times with tetrahydrofuran to obtain a brown solid compound 3 (nitro indole salt) in a yield of 65%.

[0068] Example 2

[0069] Battery Assembly:

[0070] First, carbon black, polyvinylidene fluoride (PVDF) binder and nitroindole salt are mixed in a mass ratio of 7:2:1, and the mixture is dispersed in N-methylpyrrolidone (NMP) solvent to form a uniform slurry. To ensure thorough mixing, the slurry is continuously stirred in a stirrer for several hours until there are no visible particles or lumps. The obtained uniform slurry is evenly coated on the molybdenum foil current collector by blade coating to ensure that the thickness of the coating is consistent. After coating, the molybdenum foil coated with the slurry is placed in a vacuum drying oven and dried at 70 ° C for 24 hours to ensure complete evaporation of the NMP solvent. The dried coating has uniform thickness and stable adhesion, with an average load weight of about 1g / cm 2 Subsequently, under an inert gas environment (such as nitrogen or argon), the dried coated molybdenum foil is assembled into a Swagelok-type battery in sequence with an aluminum foil anode, an AlCl3:[EMIm]Cl electrolyte, and a Whatman GF / C separator. Using aluminum foil as the anode material and AlCl3:[EMIm]Cl electrolyte as the electrolyte ensures that the battery has good ion conductivity and stable electrochemical performance. The Whatman GF / C separator serves as the battery's isolation layer, preventing short circuits between electrodes and ensuring smooth ion migration.

[0071] Figure 1 Figure a shows an SEM image of a nitroindole salt material. This image shows that the nitroindole salt exhibits an excellent flexible flocculent morphology. The flocculent skeleton has multiple active functional groups capable of adsorbing and desorbing aluminum ions. The flexible flocculent structure facilitates the entry and exit of ions.

[0072] Figure 1 (b) shows the rate performance of the battery. Measured at current densities ranging from 0.1A / g to 2A / g, the average specific capacity at 0.2A / g was 109mAh / g, while values ​​of 94, 80, 72, and 58mAh / g were obtained at 0.2, 0.5, 1.0A / g, and 2.0A / g, respectively. The discharge capacity at 1.0A / g accounted for 50.8% of that at 0.2A / g. When the current density returned to 0.1A / g, the average discharge capacity returned to 106mAh.

[0073] Figure 1 Figure c shows the charge-discharge curves of the battery at different current densities. Measurements were taken at current densities ranging from 100 mA / g to 2000 mA / g. This figure shows that the battery assembled with nitroindole salts as the active material maintains a high capacity and a stable voltage plateau at various current densities. When the current density returns to 100 mA / g, the average charge-discharge capacity essentially returns to its previous level.

[0074] Figure 1Figure d shows the battery's long-term cycling curve and Coulombic efficiency curve. Long-term cycling tests were conducted at a current density of 200 mA / g. The battery underwent a slow activation process before 100 cycles. After activation, the battery's charge capacity stabilized at around 100 mAh / g. After 800 cycles, it still retained a capacity close to 100 mAh / g, demonstrating an exceptionally flat discharge plateau.

[0075] In summary, the present invention provides a new positive electrode material for aluminum ion batteries. After adding a nitroindole salt, the positive electrode material for aluminum ion batteries enables the aluminum ion battery to exhibit an ultra-flat discharge platform and excellent electrochemical performance during the charge and discharge process, significantly improving the overall performance of the aluminum ion battery and having broad application prospects.

Claims

1. A positive electrode material for an aluminum ion battery, characterized in that: Comprising carbon materials, binders and nitroindole salts; The structure of the nitro indole salt is as follows:

2. The aluminum ion battery positive electrode material according to claim 1, wherein: The mass ratio of the carbon material, the binder and the nitroindole salt is 7:2:

1.

3. The aluminum ion battery positive electrode material according to claim 1, wherein: The carbon material includes carbon black.

4. The aluminum ion battery positive electrode material according to claim 1, wherein: The binder includes polyvinylidene fluoride.

5. The aluminum ion battery positive electrode material according to claim 1, wherein: The synthesis method of the nitro indole salt comprises the following steps: 4-Nitrophenylhydrazine and 3-methyl-2-butanone were mixed in a first organic solvent under a protective atmosphere and then heated under reflux to obtain Will and iodoethane are dissolved in a second organic solvent under a protective atmosphere, mixed and heated under reflux to obtain the product.

6. The aluminum ion battery positive electrode material according to claim 5, wherein: The protective atmosphere includes nitrogen, argon or helium; The first organic solvent comprises a mixed solution of acetic acid and ethanol; The second organic solvent includes acetonitrile.

7. An aluminum ion battery positive electrode, characterized in that: The invention comprises the aluminum ion battery positive electrode material as claimed in claim 1.

8. An aluminum ion battery, characterized in that: The invention comprises the aluminum ion battery positive electrode as claimed in claim 7.

9. The aluminum ion battery according to claim 8, wherein: The aluminum ion battery also includes an [EMIm]Cl electrolyte.

10. The aluminum ion battery according to claim 8, characterized in that: Includes Whatman GF / C diaphragm.

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