Binder for positive electrode of aluminum ion secondary battery and aluminum secondary battery containing binder

Abstract

The invention provides a binder for a positive electrode of an aluminum ion secondary battery and the aluminum secondary battery comprising the binder. Polymer molecules contained in the binder for the positive electrode have nitrogen-containing aromatic groups. The binder for the positive electrode is charged for the first time through an aluminum ion secondary battery, nitrogen cations are generated in situ and exist stably, the interface of a positive electrode electrolyte is improved, and the ionic conductivity is improved. According to the binder for the aluminum ion battery positive electrode, the performance of an aluminum ion secondary battery under high-activity substance surface loading can be fully exerted, and the prepared battery is high in capacity and good in rate and cycle performance.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of aluminum ion secondary battery anode binder and the aluminum secondary battery comprising it, the anode binder comprising polymer molecules has nitrogen-containing aromatic group. BACKGROUND

[0002] As the most abundant metal element on earth, aluminum metal is low in cost, good in chemical stability, and its theoretical specific capacity as negative electrode is as high as 2982 mAh g -1 Based on ionic liquid electrolyte, secondary aluminum ion battery has many advantages such as high safety, long cycle life and excellent low temperature performance. Secondary aluminum ion battery is expected to be applied in large-scale energy storage and low-temperature power supply in the future, and has broad market prospects.

[0003] Increasing the surface loading of positive active material (> 10 mg cm -2 ), to reduce the proportion of non-active materials such as current collector, separator, outer package, is the necessary requirement to promote the commercialization process of aluminum ion battery. However, the thickness of the electrode sheet will be significantly increased by the high surface loading, which will significantly increase the ion transport impedance. For example, graphite anode, literature reports that the surface loading of the electrode sheet prepared by traditional binder decreases linearly by 6~9 mAh g -2 -1 Therefore, the effective utilization of active material under high surface loading is the key to solving the problem.

[0004] ​Binders for the positive electrode of batteries are essential raw materials in battery manufacturing, serving to adhere the positive electrode material and conductive agent to the current collector. As a contact medium between the positive electrode active material and the electrolyte, binder molecules play a crucial role in electrolyte wetting and ion transport. Patent CN201210227905.3 discloses a method for preparing an aqueous binder for lithium-ion batteries, involving mixing unsaturated hydrophilic monomers, unsaturated lipophilic monomers, and additives, followed by polymerization with an initiator. Lithium-ion batteries prepared with this binder exhibit good rate performance. CN202180044184.X discloses a positive electrode binder for lithium secondary batteries, containing structural units derived from cationic (meth)acrylate monomers containing at least one cation, which improves battery cycle stability. CN201680026985.2 discloses a binder for the positive electrode of a lithium-ion secondary battery. By setting the content of oil-soluble free radical initiator in the binder below a predetermined value, the internal resistance of the electrode is reduced, resulting in a lithium-ion secondary battery with high-efficiency discharge characteristics. Currently, the binders used in aluminum-ion batteries directly adopt the lithium battery system, with polyvinylidene fluoride (PVDF) and polyacrylonitrile copolymers (such as LA132 or LA133) being the most commonly used. These polymers have poor compatibility with ionic liquid electrolytes and low wettability, especially when highly active materials are loaded onto the surface, resulting in a significant decrease in battery capacity. Moreover, the polar functional groups of PVDF and LA series polymers have little interaction with the weakly polar graphite surface, limiting the bonding performance when highly active materials are loaded onto the surface. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to alleviate the significant decrease in the specific capacity of the positive electrode when the surface loading of the positive electrode of the aluminum-ion battery is increased. The present invention provides a binder for the positive electrode of the aluminum-ion secondary battery, as well as the positive electrode and the aluminum-ion secondary battery, so that the performance of the positive electrode material can be fully utilized under high surface loading.

[0006] To achieve the above objectives, the first aspect of the present invention provides a binder for the positive electrode of an aluminum-ion secondary battery, the binder comprising a polymer formed by polymerizing one or more alkenyl monomers, wherein the alkenyl monomers have nitrogen-containing aromatic groups.

[0007] The alkenyl monomer is selected from one of the monomer structures represented by the following formulas 1-6:

[0008]

[0009] R1 and R3 are hydrogen or alkyl groups having 1 to 4 carbon atoms, and R1 and R3 may be the same or different. R2 is a nitrogen-containing aromatic group, n is 0 or an integer greater than 0, and R4-R7 are selected from hydrogen, alkyl, alkoxy or halogen, and R4-R7 may be the same or different.

[0010] wherein the nitrogen-containing aromatic group R2 is selected from one of nitrogen-grafted phenoxazine, phenothiazine, phenoselenazine, carbazole, pyrrole, indole, aniline, 4-methoxyaniline, diphenylamine, 4,4'-dimethoxydiphenylamine, N-methylaniline.

[0011] Preferably, based on formula 1-6, the alkenyl monomer is preferably selected from one of the structures shown in formula 7-9:

[0012]

[0013] wherein R1, R3 are preferably hydrogen or methyl, R1, R3 are the same or different, R2 is a nitrogen-containing aromatic group, preferably phenothiazine, and m is preferably 2-4.

[0014] The positive electrode binder comprises 5% to 15% by weight of the polymer and 85% to 95% by weight of the solvent. The solvent used is selected from one or more of toluene, tetrahydrofuran, N,N-dimethylformamide dimethyl sulfoxide, N-methyl pyrrolidone, preferably N-methyl pyrrolidone.

[0015] In the present application, the polymer is polymerized from one or more alkenyl monomers in combination with a crosslinking agent at a molar ratio of 1:0~0.2; the polymerization method of the polymer is selected from one of free radical polymerization, anionic polymerization, cationic polymerization, preferably free radical polymerization.

[0016] Preferably, the polymer is prepared by the following specific method: the crosslinking agent and the above-mentioned alkenyl monomer with a nitrogen-containing aromatic group are weighed according to a molar ratio of 0~0.2:1 as raw materials, preferably a molar ratio of 0.05:1, dissolved in an organic solvent, preferably N,N-dimethylformamide. An initiator is added to initiate the polymerization reaction, preferably azobisisobutyronitrile; the polymerization reaction is stirred at 60~120℃ under a nitrogen atmosphere for 6~48 hours. After the reaction is completed, the organic solvent is removed by vacuum pumping, and the obtained solid is washed with methanol and dried to obtain a polymer derived from at least one alkenyl monomer structural unit. The crosslinking agent is selected from one or more of 1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-bis(1-methylvinyl)benzene, 1,3,5-triisopropylbenzene, ethylene glycol dimethacrylate, N,N'-vinylbisacrylamide, 1,4-diacryloylpiperazine, pentaerythritol tetraacrylate, preferably 1,3-bis(1-methylvinyl)benzene; the weight ratio of the organic solvent to the alkenyl monomer is 0.5~10:1, preferably 1.75:1.

[0017] In the present application, the alkenyl monomer with a nitrogen-containing aromatic group of formula 7-9 is prepared by 1.1, 1.2 and 1.3 respectively as follows.

[0018] 1.1 Preparation of alkenyl monomers with alkenyl ester structures. A base and a nitrogen-containing aromatic compound were weighed in a 1:1 molar ratio, dissolved in an organic solvent under a nitrogen atmosphere, and stirred at 0–60 °C for 0.5–2 hours. A bromool with the structure Br-(CH2) was added to the solution. m -OH, wherein m is preferably 2 to 4, wherein the molar ratio of nitrogen-containing aromatic compound to bromoethanol is 1:1.1, and the mixture is stirred at 0–60 °C for 12–48 hours; triethylamine is added to the solution, wherein the molar ratio of nitrogen-containing aromatic compound to triethylamine is 1:1.2, and an alkenyl chloride with the structure R1-CH=CH-COCl is added to the solution, wherein R1 is preferably hydrogen or methyl, wherein the molar ratio of nitrogen-containing aromatic compound to alkenyl chloride is 1:1.2, and the mixture is stirred at 0–30 °C for 12–48 hours. After the reaction is complete, the organic solvent is removed by vacuum removal, and the resulting product is purified by chromatographic separation or recrystallization to obtain an alkenyl monomer with an alkenyl ester structure;

[0019] 1.2 Preparation of alkenyl monomers with alkenylamide structures. A base and a nitrogen-containing aromatic compound were weighed at a molar ratio of 1:1, dissolved in an organic solvent under a nitrogen atmosphere, and stirred at 0–60 °C for 0.5–2 hours. A bromoamine with the structure Br-(CH2) was added to the solution. m -NH-R3, wherein m is preferably 2 to 4, R3 is preferably hydrogen or methyl, wherein the molar ratio of nitrogen-containing aromatic compound to bromoamine is 1:1.1, and the mixture is stirred at 0–60°C for 12–48 hours; triethylamine is added to the solution, wherein the molar ratio of nitrogen-containing aromatic compound to triethylamine is 1:1.2, and an alkenyl acyl chloride with the structure R1-CH=CH-COCl is added to the solution, wherein R1 is preferably hydrogen or methyl, wherein the molar ratio of nitrogen-containing aromatic compound to alkenyl acyl chloride is 1:1.2, and the mixture is stirred at 0–30°C for 12–48 hours. After the reaction is complete, the organic solvent is removed by vacuum removal, and the resulting product is purified by chromatographic separation or recrystallization to obtain an alkenyl monomer with an alkenyl amide structure;

[0020] 1.3 Preparation of alkenyl monomers with styrene structure. A base and a nitrogen-containing aromatic compound are weighed at a molar ratio of 1:1, dissolved in an organic solvent under a nitrogen atmosphere, and stirred at 0–60°C for 0.5–2 hours. An alkenyl compound is then added to the solution, and the mixture is stirred at 0–60°C for 12–48 hours. The molar ratio of the nitrogen-containing aromatic compound to the alkenyl monomer is 1.1:1. After the reaction is complete, the organic solvent is removed under vacuum. The resulting product, after chromatographic separation or recrystallization purification, is the alkenyl monomer with a styrene structure.

[0021] The alkenyl compound mentioned in 1.3 is selected from one represented by Formula 10:

[0022]

[0023] wherein R1 is preferably hydrogen or methyl, m is preferably 2 to 4, and X is chlorine, bromine or iodine, preferably bromine.

[0024] In the present application 1.1 or 1.2 or 1.3, the nitrogen-containing aromatic compound is selected from one of phenoxazine, phenothiazine, phenoselenazine, carbazole, pyrrole, indole, aniline, 4-methoxyaniline, diphenylamine, 4,4'-dimethoxydiphenylamine, N-methylaniline, preferably phenothiazine; the base is preferably sodium tert-butoxide or sodium hydride; and the organic solvent is preferably anhydrous tetrahydrofuran or anhydrous N,N-dimethylformamide.

[0025] The second aspect of the present application provides a positive electrode for an aluminum ion secondary battery, which comprises the above-mentioned positive electrode binder and a positive electrode active material, wherein the positive electrode active material comprises one or a combination of natural graphite, artificial graphite, hard carbon, graphene, carbon nanotubes, preferably natural flake graphite; and wherein the content of the positive electrode binder is 1 to 50 parts by weight, preferably 3 to 15 parts by weight, relative to 100 parts by weight of the total weight of the positive electrode for an aluminum ion secondary battery.

[0026] The manufacturing process of the positive electrode for an aluminum ion secondary battery comprises the following steps:

[0027] The above-mentioned positive electrode binder for an aluminum ion secondary battery is weighed, diluted in N-methylpyrrolidone, and then added to the positive electrode active material in batches to grind into a slurry, which is uniformly coated on a clean positive electrode current collector, and then dried at 120±10 o C, and then compacted to obtain a positive electrode sheet with a surface loading of 5 to 25 mg / cm 2 .

[0028] The positive electrode current collector is selected from platinum (Pt), gold (Au), palladium (Pd), iridium (Ir), silver (Ag), ruthenium (Ru), nickel (Ni), molybdenum (Mo), chromium (Cr), carbon (C), titanium (Ti), tungsten (W), titanium nitride (TiN), or an alloy thereof; or aluminum (Al) or stainless steel treated with the above-mentioned substances. The shape of the positive electrode current collector is one of a foil, a film, a sheet, a punched form, a porous body, or a foam.

[0029] The third aspect of the present application provides an aluminum ion secondary battery, which comprises the above-mentioned positive electrode for an aluminum ion secondary battery, an aluminum metal negative electrode, an electrolyte and a separator interposed therebetween; wherein the aluminum metal negative electrode is a 30-μm-thick aluminum foil; and the electrolyte is an ionic liquid comprising AlCl4 - and Al2Cl7 - , preferably an ionic liquid prepared from 1-ethyl-3-methylimidazole chloride ([EMIm]Cl) and aluminum chloride (AlCl3) at a molar ratio of 1:1.3 to 2.

[0030] The specific preparation steps of the aluminum ion secondary battery include:

[0031] The positive electrode and the aluminum metal negative electrode of the aluminum ion secondary battery are cut into a certain area according to the size of the battery capacity specification, a glass fiber battery separator is used, an aluminum ion secondary bag battery is prepared, an aluminum plastic film is packaged, and vacuum drying is performed at 60±10 o C for three hours, and then the aluminum ion secondary bag battery is transferred to a dry nitrogen-filled glove box, an electrolyte is injected, and the battery is packaged.

[0032] The fourth aspect of the present application provides the use of the binder for the positive electrode of the aluminum ion secondary battery in the positive electrode of the aluminum ion secondary battery, and the use of the positive electrode of the aluminum ion secondary battery in the aluminum ion secondary battery.

[0033] Compared with the prior art, the binder for the positive electrode of the aluminum ion secondary battery provided by the present application generates nitrogen cations in situ and stably exists after the first charging of the aluminum ion secondary battery, improves the positive electrode electrolyte interface, and improves the ion conductivity, so that the performance of the aluminum ion secondary battery with high active material surface load is fully utilized. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The redox mechanism diagram of the binder in Example 1 in the aluminum ion battery.

[0035] Figure 2 The redox CV diagrams of the binder in Example 1 and the graphite positive electrode in the aluminum ion battery, respectively. The induced current has been normalized.

[0036] Figure 3 The performance comparison of the aluminum ion batteries prepared using different binders under different positive electrode active material surface loads. The binders in Example 1, Comparative Example 1 and Comparative Example 2 are used to prepare positive electrode sheets, which are assembled into aluminum ion batteries with different graphite surface loads, and the charge-discharge test is performed at a charge-discharge rate of 2C (0.2 A / g), so as to obtain the relationship diagram of the discharge specific capacity and the active material surface load, wherein the horizontal coordinate is the active material surface load (mg / cm 2 ), and the vertical coordinate is the battery discharge specific capacity (mAh / g).

[0037] Figure 4 The graphite positive electrode sheet is prepared using the binder in Example 1, and the aluminum ion battery is assembled to detect the charge-discharge rate performance, so as to obtain the relationship diagram of the battery voltage and the capacity percentage, wherein the graphite surface load is 10.2 mg / cm 2 , the horizontal coordinate is the battery capacity percentage (%), and the vertical coordinate is the battery voltage (V).

[0038] Figure 5To make a graphite positive electrode sheet with the binder in Example 1, an aluminum ion test battery was assembled and subjected to charge-discharge cycle test at a charge-discharge rate of 2C (0.2 A / g), thereby obtaining a discharge capacity cycle stability graph, in which the graphite surface loading was 20 mg / cm 2 , the abscissa was the number of charge-discharge cycles, and the ordinate was the battery discharge capacity retention rate (%). DETAILED DESCRIPTION

[0039] The present application provides a binder for aluminum ion secondary battery positive electrode, and a positive electrode and an aluminum ion secondary battery comprising the same, the binder having a nitrogen-containing aromatic group, having redox activity in an aluminum ion secondary battery. Figure 1 After the first charge, the nitrogen atom is oxidized to a nitrogen cation, and the reduction of the nitrogen cation requires a voltage of 0.65 V, which is beyond the operating voltage range of the aluminum ion battery (1.0-2.45 V). Therefore, the binder for the aluminum ion secondary battery positive electrode provided by the present application generates nitrogen cations in situ and stably exists Figure 2 , the cationic structure improves the wettability of the ionic liquid to the graphite positive electrode, enhances the diffusion kinetics of the aluminum chloride anion to the deep part of the graphite positive electrode, and fully develops the performance of the aluminum ion battery under high active material surface loading.

[0040] The binder for the aluminum ion secondary battery positive electrode, and the aluminum secondary battery comprising the same, according to the present application, are further specifically described below in conjunction with examples.

[0041] Unless otherwise specified in the examples, the techniques and conditions were carried out according to the techniques and conditions described in the literature in the art or according to the product instructions, and the reagents or instruments not specified by the manufacturer were all conventional products available on the market.

[0042] Example 1

[0043] The present application provides a binder for aluminum ion secondary battery positive electrode, and a positive electrode and an aluminum ion secondary battery comprising the same, the binder having a nitrogen-containing aromatic group, having redox activity in an aluminum ion secondary battery.

[0044] A binder for aluminum ion secondary battery positive electrode, the positive electrode binder comprising 15% by weight of a polymer and 85% by weight of N-methyl pyrrolidone solvent, the polymer being polymerized from an alkenyl monomer represented by formula 11 and a crosslinking agent represented by formula 12.

[0045]

[0046] The preparation method of the binder for aluminum ion secondary battery positive electrode is: (1) weigh 10 parts by weight of sodium tert-butoxide and 20.8 parts by weight of phenothiazine, add 300 parts by weight of dry N,N-dimethylformamide, and under a nitrogen atmosphere, at 25 oC for 2 hours, 20 parts by weight of 4-(2-bromoethyl)styrene was added to the reaction solution, and the temperature was raised to 60 o C for 24 hours. After the reaction was completed, the organic solvent was removed by vacuum pumping, and the resulting product was separated by chromatography to obtain an unsaturated polymerization monomer, which was an alkenyl monomer having a nitrogen-containing aromatic group; (2) 20 parts by weight of the polymerization monomer and 0.5 parts by weight of 1,3-bis(1-methylvinyl)benzene were dissolved in 35 parts by weight of N,N-dimethylformamide, and the mixture was stirred in a reaction kettle, followed by purging with nitrogen to remove oxygen for 1 hour at a nitrogen flow rate of 25 ml / min. The temperature was raised to 75 o C and kept constant, and then 0.1 parts by weight of azobisisobutyronitrile was added. After polymerization for 48 hours, the organic solvent was removed by vacuum pumping, and the resulting solid was washed with methanol and dried in a vacuum oven for 24 hours to obtain a polymer; (3) the resulting polymer was dissolved in N-methylpyrrolidone at a weight ratio of 15:85 to obtain a binder for a positive electrode of an aluminum ion secondary battery.

[0047] Preparation of a positive electrode and an aluminum ion secondary battery: natural flake graphite was used as a positive electrode material, the particle size of the graphite powder was 100 mesh, and the purity was greater than 99%. The graphite and the binder described above were added to N-methylpyrrolidone to form a slurry, and a positive electrode sheet having a basic composition of 90 parts by weight of graphite and 10 parts by weight of polymer was prepared. The positive electrode sheet was dried and compacted, and an aluminum foil was used as a negative electrode sheet. An ionic liquid prepared from 1-ethyl-3-methylimidazole ([EMIm]Cl) and aluminum chloride (AlCl3) at a molar ratio of 1:1.5 was used as an electrolyte to assemble an aluminum ion secondary battery for charge and discharge tests.

[0048] Example 2

[0049] The present embodiment provides a binder for a positive electrode of an aluminum ion secondary battery and a method for preparing the same, as well as a positive electrode and an aluminum ion secondary battery and methods for preparing the same.

[0050] A binder for a positive electrode of an aluminum ion secondary battery, the positive electrode binder comprising 15% by weight of a polymer and 85% by weight of an N-methylpyrrolidone solvent, the polymer being polymerized from an alkenyl monomer represented by Formula 11.

[0051]

[0052] A method for preparing a binder for a positive electrode of an aluminum ion secondary battery, comprising: (1) weighing 10 parts by weight of sodium tert-butoxide and 20.8 parts by weight of phenothiazine, adding 300 parts by weight of dry N,N-dimethylformamide, and stirring under a nitrogen atmosphere at 25 o C for 2 hours, 20 parts by weight of 4-(2-bromoethyl)styrene was added to the reaction solution, and the temperature was raised to 60 oStirred at C for 24 hours. After the reaction, the organic solvent was removed by vacuum. The obtained product was separated by chromatography to obtain the unsaturated polymer monomer, which is the alkenyl monomer with nitrogen-containing aromatic groups; (2) 20 parts by weight of polymer monomer were dissolved in 35 parts by weight of N,N-dimethylformamide, and stirred and mixed evenly in the reaction vessel. Then, nitrogen gas was introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and the mixture was heated to 75°C. o C and keep the temperature constant, then add 0.1 parts by weight of azobisisobutyronitrile for polymerization. After reacting for 48 hours, remove the organic solvent under vacuum, wash the obtained solid with methanol, and dry it under vacuum for 24 hours to obtain the polymer; (3) Dissolve the obtained polymer in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum ion secondary battery.

[0053] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0054] Example 3

[0055] This embodiment provides a binder for the positive electrode of an aluminum-ion secondary battery and its preparation method, as well as the positive electrode and the aluminum-ion secondary battery and their preparation.

[0056] A binder for the positive electrode of an aluminum-ion secondary battery, the binder comprising 15% by weight of a polymer and 85% by weight of an N-methylpyrrolidone solvent, the polymer being polymerized from an alkenyl monomer represented by Formula 13.

[0057]

[0058] The preparation method of the binder for the positive electrode of aluminum-ion secondary battery is as follows: (1) Weigh 10 parts by weight of sodium tert-butoxide and 19.1 parts by weight of phenoxazine, add 300 parts by weight of dry N,N-dimethylformamide, and heat under nitrogen atmosphere at 25°C. o Stirring at C for 2 hours, then adding 20 parts by weight of 4-(2-bromoethyl)styrene to the reaction solution, and heating to 60°C. o Stirred at C for 24 hours. After the reaction, the organic solvent was removed by vacuum. The obtained product was separated by chromatography to obtain the unsaturated polymer monomer, which is the alkenyl monomer with nitrogen-containing aromatic groups; (2) 20 parts by weight of polymer monomer were dissolved in 35 parts by weight of N,N-dimethylformamide, and stirred and mixed evenly in the reaction vessel. Then, nitrogen gas was introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and the mixture was heated to 75°C. o C and keep the temperature constant, then add 0.1 parts by weight of azobisisobutyronitrile for polymerization. After reacting for 48 hours, remove the organic solvent under vacuum, wash the obtained solid with methanol, and dry it under vacuum for 24 hours to obtain the polymer; (3) Dissolve the obtained polymer in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum ion secondary battery.

[0059] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0060] Example 4

[0061] This embodiment provides a binder for the positive electrode of an aluminum-ion secondary battery and its preparation method, as well as the positive electrode and the aluminum-ion secondary battery and their preparation.

[0062] A binder for the positive electrode of an aluminum-ion secondary battery, the binder comprising 15% by weight of a polymer and 85% by weight of an N-methylpyrrolidone solvent, the polymer being copolymerized from alkenyl monomers represented by Formula 11 and Formula 13.

[0063]

[0064] The preparation method of the binder for the positive electrode of aluminum-ion secondary battery is as follows: (1) Using the preparation methods of alkenyl monomers with nitrogen-containing aromatic groups shown in Examples 2 and 3, alkenyl monomers of Formula 11 and Formula 13 are prepared respectively. (2) 10 parts by weight of alkenyl monomer (Formula 11) and 10 parts by weight of alkenyl monomer (Formula 13) are dissolved in 35 parts by weight of N,N-dimethylformamide, stirred and mixed evenly in a reaction vessel, and then nitrogen gas is introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and heated to 75°C. o C and keep the temperature constant, then add 0.1 parts by weight of azobisisobutyronitrile for polymerization. After reacting for 48 hours, remove the organic solvent under vacuum, wash the obtained solid with methanol, and dry it under vacuum for 24 hours to obtain the polymer; (3) Dissolve the obtained polymer in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum ion secondary battery.

[0065] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0066] Example 5

[0067] This embodiment provides a binder for the positive electrode of an aluminum-ion secondary battery and its preparation method, as well as the positive electrode and the aluminum-ion secondary battery and its preparation method.

[0068] A binder for the positive electrode of an aluminum-ion secondary battery, the binder comprising 15% by weight of a polymer and 85% by weight of an N-methylpyrrolidone solvent, the polymer being polymerized from an alkenyl monomer represented by Formula 14.

[0069]

[0070] The preparation method of the binder for the positive electrode of aluminum-ion secondary battery is as follows: (1) Weigh 10 parts by weight of sodium tert-butoxide and 20.8 parts by weight of phenothiazine, add 300 parts by weight of dry N,N-dimethylformamide, and heat at 25°C in the absence of air. oStirring at C for 2 hours, then adding 18.6 parts by weight of 4-vinylbenzyl bromide to the reaction solution, and heating to 60°C. o Stirred at C for 24 hours. After the reaction, the organic solvent was removed by vacuum. The obtained product was separated by chromatography to obtain the unsaturated polymer monomer, which is the alkenyl monomer with nitrogen-containing aromatic groups; (2) 20 parts by weight of polymer monomer were dissolved in 35 parts by weight of N,N-dimethylformamide, and stirred and mixed evenly in the reaction vessel. Then, nitrogen gas was introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and the mixture was heated to 75°C. o C and keep the temperature constant, then add 0.1 parts by weight of azobisisobutyronitrile for polymerization. After reacting for 48 hours, remove the organic solvent under vacuum, wash the obtained solid with methanol, and dry it under vacuum for 24 hours to obtain the polymer; (3) Dissolve the obtained polymer in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum ion secondary battery.

[0071] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0072] Example 6

[0073] This embodiment provides a binder for the positive electrode of an aluminum-ion secondary battery and its preparation method, as well as the positive electrode and the aluminum-ion secondary battery and their preparation method.

[0074] A binder for the positive electrode of an aluminum-ion secondary battery, the binder comprising 15% by weight of a polymer and 85% by weight of an N-methylpyrrolidone solvent, the polymer being polymerized from an alkenyl monomer represented by Formula 15.

[0075]

[0076] The preparation method of the binder for the positive electrode of aluminum-ion secondary battery is as follows: (1) Weigh 10 parts by weight of sodium tert-butoxide and 20.8 parts by weight of phenothiazine, add 300 parts by weight of dry N,N-dimethylformamide, and heat under a nitrogen atmosphere at 25°C. o Stirring at C for 2 hours, then adding 14.3 parts by weight of 2-bromoethanol to the reaction solution, and heating to 60°C. o Stir at C for 24 hours. Add 8.8 parts by weight of triethylamine and 11.3 parts by weight of acryloyl chloride to the reaction solution. o Stirred at C for 24 hours. After the reaction, the organic solvent was removed by vacuum. The obtained product was separated by chromatography to obtain the unsaturated polymer monomer, which is the alkenyl monomer with nitrogen-containing aromatic groups; (2) 20 parts by weight of polymer monomer were dissolved in 35 parts by weight of N,N-dimethylformamide, and stirred and mixed evenly in the reaction vessel. Then, nitrogen gas was introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and the mixture was heated to 75°C. oC and keep the temperature constant, then add 0.1 parts by weight of azobisisobutyronitrile for polymerization. After reacting for 48 hours, remove the organic solvent under vacuum, wash the obtained solid with methanol, and dry it under vacuum for 24 hours to obtain the polymer; (3) Dissolve the obtained polymer in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum ion secondary battery.

[0077] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0078] Example 7

[0079] This embodiment provides a binder for the positive electrode of an aluminum-ion secondary battery and its preparation method, as well as the positive electrode and the aluminum-ion secondary battery and their preparation method.

[0080] A binder for the positive electrode of an aluminum-ion secondary battery, the binder comprising 15% by weight of a polymer and 85% by weight of an N-methylpyrrolidone solvent, the polymer being polymerized from an alkenyl monomer represented by Formula 16.

[0081]

[0082] The preparation method of the binder for the positive electrode of aluminum-ion secondary battery is as follows: (1) Weigh 10 parts by weight of sodium tert-butoxide and 20.8 parts by weight of phenothiazine, add 300 parts by weight of dry N,N-dimethylformamide, and heat under a nitrogen atmosphere at 25°C. o Stirring at C for 2 hours, then adding 14.2 parts by weight of 2-bromoethylamine to the reaction solution, and heating to 60°C. o Stir at C for 24 hours. Add 8.8 parts by weight of triethylamine and 11.3 parts by weight of acryloyl chloride to the reaction solution. o Stirred at C for 24 hours. After the reaction, the organic solvent was removed by vacuum. The obtained product was separated by chromatography to obtain the unsaturated polymer monomer, which is the alkenyl monomer with nitrogen-containing aromatic groups; (2) 20 parts by weight of polymer monomer were dissolved in 35 parts by weight of N,N-dimethylformamide, and stirred and mixed evenly in the reaction vessel. Then, nitrogen gas was introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and the mixture was heated to 75°C. o C and keep the temperature constant, then add 0.1 parts by weight of azobisisobutyronitrile for polymerization. After reacting for 48 hours, remove the organic solvent under vacuum, wash the obtained solid with methanol, and dry it under vacuum for 24 hours to obtain the polymer; (3) Dissolve the obtained polymer in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum ion secondary battery.

[0083] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0084] Comparative Example 1

[0085] The preparation method of the binder for the positive electrode of the aluminum-ion battery in this comparative example is as follows: 20 parts by weight of styrene are dissolved in 35 parts by weight of N,N-dimethylformamide and mixed evenly. Nitrogen gas is then introduced to remove oxygen for 1 hour at a flow rate of 25 ml / min, and the mixture is heated to 75°C. o The mixture is kept at a constant temperature and then 0.1 parts by weight of azobisisobutyronitrile is added for polymerization. After reacting for 24 hours, the organic solvent is removed by vacuum extraction. The resulting solid is washed with methanol and dried under vacuum for 24 hours. The resulting solid is dissolved in N-methylpyrrolidone solvent at a weight ratio of 15:85 to obtain the binder for the positive electrode of aluminum-ion secondary batteries.

[0086] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0087] Comparative Example 2

[0088] In this comparative example, the binder used for the positive electrode of the aluminum-ion battery was a commercially available PVDF binder (Arkema HSV900) for comparative testing.

[0089] The preparation of the positive electrode and the aluminum-ion secondary battery is the same as in Example 1.

[0090] The battery cycle performance of Examples 1-7 and Comparative Examples 1-2 is shown in Table 1. Compared with polystyrene (Comparative Example 1) and PVDF (Comparative Example 2), the binder for the positive electrode of the aluminum-ion secondary battery provided by the present invention (Examples 1-7) all have higher discharge specific capacity. Among them, Example 1 has the best performance, with a discharge specific capacity of up to 90 mAh / g after 10 cycles, and still retains 99% of the discharge specific capacity after 500 cycles.

[0091] Figure 3 The discharge specific capacity of aluminum secondary batteries in Example 1 and Comparative Examples 1-2 under different graphite cannula loads is presented. In Example 1, the battery discharge specific capacity exceeds 19 mg / cm² under cannula loads. 2 Even at high surface area, it still has a discharge specific capacity of about 70 mAh / g. The battery performance under high surface area is better than that of Comparative Example 1 and Comparative Example 2, which proves that the binder for the positive electrode of aluminum-ion secondary battery provided by the present invention can give full play to the performance of its positive electrode material under high surface area.

[0092] pass Figure 4 It can be seen that the aluminum secondary battery prepared by the binder in Example 1 can maintain more than 80% of its capacity at a charge-discharge rate of 5C, and has excellent rate performance.

[0093] pass Figure 5 It can be seen that the aluminum secondary battery prepared by the binder in Example 1 still has a 92% capacity retention rate after 2000 cycles at a 2C charge-discharge rate, demonstrating excellent cycle stability.

[0094] [Table 1]

Claims

1. A binder for the positive electrode of an aluminum-ion secondary battery, characterized in that, The binder for the positive electrode comprises a polymer formed by polymerization of one or more alkenyl monomers, wherein alkenyl functional groups participate in the polymerization reaction, and the alkenyl monomers have nitrogen-containing aromatic groups.

2. The binder for the positive electrode of an aluminum-ion secondary battery according to claim 1, characterized in that, The alkenyl monomer is selected from one of the monomer structures represented by the following formulas 1-6: R1 and R3 are hydrogen or alkyl groups having 1 to 4 carbon atoms, and R1 and R3 may be the same or different. R2 is a nitrogen-containing aromatic group, n is 0 or an integer greater than 0, and R4-R7 are selected from hydrogen, alkyl, alkoxy or halogen, and R4-R7 may be the same or different.

3. The binder for the positive electrode of an aluminum-ion secondary battery according to claim 2, characterized in that, The nitrogen-containing aromatic group is selected from one of nitrogen-grafted phenoxazine, phenothiazine, phenotelezine, carbazole, pyrrole, indole, aniline, 4-methoxyaniline, diphenylamine, 4,4'-dimethoxydiphenylamine, and N-methylaniline.

4. The binder for the positive electrode of an aluminum-ion secondary battery according to any one of claims 1-3, characterized in that, The alkenyl monomer is selected from one of the structures shown in Formulas 7-9: Where R1 and R3 are hydrogen or methyl, R1 and R3 may be the same or different, R2 is nitrogen-grafted phenthiazide, and m is 2-4.

5. The binder for the positive electrode of an aluminum-ion secondary battery according to any one of claims 1-4, characterized in that, The polymer is formed by polymerizing one or more alkenyl monomers with a crosslinking agent at a molar ratio of 1:0 to 0.

2.

6. The binder for the positive electrode of an aluminum-ion secondary battery according to claim 5, characterized in that, The crosslinking agent is selected from one or more combinations of 1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-di(1-methylvinyl)benzene, 1,3,5-triisopropylbenzene, ethylene glycol dimethacrylate, N,N'-vinylbisacrylamide, 1,4-diacryloylpiperazine, and pentaerythritol tetraacrylate.

7. The binder for the positive electrode of an aluminum-ion secondary battery according to any one of claims 1-6, characterized in that, The polymer is prepared by the following specific method: a crosslinking agent and an alkenyl monomer with a nitrogen-containing aromatic group are weighed as raw materials, dissolved in an organic solvent, and an initiator is added to initiate a polymerization reaction. The polymerization reaction is carried out under a nitrogen atmosphere and stirred at 60-120°C for 6-48 hours. After the reaction is completed, the organic solvent is removed under vacuum, and the resulting solid is washed with methanol and dried to obtain the polymer. The crosslinking agent is selected from one or more combinations of 1,3-divinylbenzene, 1,4-divinylbenzene, 1,3-di(1-methylvinyl)benzene, 1,3,5-triisopropylbenzene, ethylene glycol dimethacrylate, N,N'-vinylbisacrylamide, 1,4-diacryloylpiperazine, and pentaerythritol tetraacrylate.

8. The binder for the positive electrode of an aluminum-ion secondary battery according to any one of claims 1-7, characterized in that, The positive electrode binder comprises 5% to 15% by weight of a polymer and 85% to 95% by weight of a solvent; the solvent is selected from one or more combinations of toluene, tetrahydrofuran, N,N-dimethylformamide dimethyl sulfoxide, and N-methylpyrrolidone.

9. A positive electrode for an aluminum-ion secondary battery, characterized in that, The positive electrode comprises a binder for the positive electrode and a positive electrode active material as described in any one of claims 1-8, wherein the content of the binder for the positive electrode is from 1 part by weight to 50 parts by weight relative to the total weight of 100 parts by weight of the positive electrode.

10. An aluminum-ion secondary battery, the aluminum-ion secondary battery comprising the positive electrode of the aluminum-ion secondary battery as described in claim 9, an aluminum metal negative electrode, an electrolyte and a separator between the two.

Images