Dispersing agent, preparation method thereof, electrode and battery

Abstract

The invention discloses a dispersing agent, a preparation method thereof, an electrode and a battery. The dispersant comprises an amide group, a keto-carbonyl group and a fluorine-containing methylene chain compound. The dispersing agent disclosed by the invention can induce polyvinylidene fluoride to form a beta phase so as to improve the interface bonding force between electrode materials, so that the electrochemical performance of a battery is improved.

Description

Technical Field

[0001] This invention relates to a dispersant and its preparation method, an electrode, and a battery. Background Technology

[0002] Polyvinylidene fluoride (PVDF) is a commonly used binder for lithium-ion battery electrodes, and its crystal structure has a significant impact on electrode performance. PVDF exists in various crystal forms, among which the β phase has the highest polarity and can significantly improve the interfacial bonding between electrode materials and between the electrode and the current collector, thereby enhancing the cycle stability and rate performance of the battery.

[0003] However, the β-phase content of PVDF is low during conventional electrode slurry preparation. Existing technologies typically promote β-phase formation through methods such as stretching, polarization, or the addition of specific additives, but these methods often suffer from problems such as complex processes, limited effectiveness, or impact on other battery performance aspects.

[0004] As a key additive in electrode slurry preparation, dispersants not only need to possess good dispersing properties but should also be able to synergize with binders. Existing lithium-ion battery dispersants primarily focus on dispersion effects, with limited research on PVDF crystal form regulation. Furthermore, some dispersants suffer from insufficient electrochemical stability or are difficult to remove, restricting their application in high-performance batteries.

[0005] Therefore, developing a dispersant that can effectively induce the formation of the β phase in PVDF and possesses excellent electrochemical stability and process adaptability, thereby reducing the amount of dispersant used, is of great significance for improving the performance of lithium-ion batteries. Summary of the Invention

[0006] The technical problem this invention aims to solve is to overcome the deficiency in existing technologies where the dispersant's insufficient control over the crystal structure of PVDF leads to poor interfacial bonding between electrode materials. This invention provides a dispersant, its preparation method, an electrode, and a battery. The dispersant of this invention can induce the formation of a β phase in polyvinylidene fluoride to improve the interfacial bonding between electrode materials, thereby enhancing the electrochemical performance of the battery.

[0007] The present invention solves the above-mentioned technical problems through the following technical solution:

[0008] The present invention provides a dispersant comprising a compound containing an amide group, a ketone carbonyl group, and a fluorinated methylene chain.

[0009] In this invention, the number of methylene groups in the fluorinated methylene chain is at least two.

[0010] In some embodiments, the amide group, ketone carbonyl group, and fluorinated methylene chain are distributed in a single compound.

[0011] In some embodiments, the amide group, ketone carbonyl group, and fluorinated methylene chain are distributed in two or more compounds.

[0012] In this invention, the dispersant preferably has the general formula shown in Formula I:

[0013] R2-NH-CO-R1-CO-R3 Formula I

[0014] in:

[0015] R1 is a C1-C5 straight-chain alkyl group;

[0016] R2 is a fluorinated methylene chain with the structure -(CF2). m -(CH2)2-, where m=2-4;

[0017] R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n = 1-3.

[0018] The applicant discovered that selecting a C1-C5 alkyl chain for R1 ensures suitable volatility of the dispersant while maintaining good dispersing performance. Selecting the fluorinated methylene chain for R2 provides good matching with the chain structure of PVDF, effectively enhancing intermolecular interactions.

[0019] R1 is preferably a C2-C4 straight-chain alkyl group, such as ethyl or propyl.

[0020] In R2, m is preferably 3.

[0021] In R3, n is preferably 2.

[0022] In a preferred embodiment, R1 is a C2 straight-chain alkyl group; R2 is a fluorinated methylene chain having the structure -(CF2). m -(CH2)2-, m=2; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n=2.

[0023] In a preferred embodiment, R1 is a C3 straight-chain alkyl group; R2 is a fluorinated methylene chain having the structure -(CF2). m -(CH2)2-, m=3; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n=3.

[0024] In a preferred embodiment, R1 is a C2 straight-chain alkyl group; R2 is a fluorinated methylene chain having the structure -(CF2). m-(CH2)2-, m=4; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n=1.

[0025] In a preferred embodiment, R1 is a C1 straight-chain alkyl group; R2 is a fluorinated methylene chain having the structure -(CF2). m -(CH2)2-, m=3; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n=2.

[0026] In a preferred embodiment, R1 is a C5 straight-chain alkyl group; R2 is a fluorinated methylene chain having the structure -(CF2). m -(CH2)2-, m=2; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n=2.

[0027] In a preferred embodiment, R1 is a C4 straight-chain alkyl group; R2 is a fluorinated methylene chain having the structure -(CF2). m -(CH2)2-, m=2; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n=2.

[0028] The present invention also provides a method for preparing a dispersant, comprising the following steps:

[0029] The dispersant is obtained by reacting a mixture of a carboxylic acid compound containing a ketone carbonyl group and a fluorinated amine compound in an organic alkaline environment.

[0030] In this invention, the ketone carbonyl group in the carboxylic acid compound containing a ketone carbonyl group is a group that is different from the carbonyl group in the carboxylic acid group.

[0031] In this invention, the mixture of carboxylic acid compound containing ketone carbonyl and fluorinated amine compound is preferably obtained by mixing a solution of carboxylic acid compound containing ketone carbonyl and a solution of fluorinated amine compound.

[0032] The solvent in the solution of the carboxylic acid compound containing the ketone carbonyl group can be conventional in the art, preferably including one or more of dichloromethane, chloroform, tetrahydrofuran and dichloroethane, such as dichloromethane.

[0033] The carboxylic acid compound containing a ketone carbonyl group preferably includes carboxylic acid compounds containing both a ketone carbonyl group and an ether bond, most preferably including carboxylic acid compounds with 5-8 carbon atoms containing both a ketone carbonyl group and an ether bond, and even more preferably including one or more of 4-oxo-5-ethoxyvalerate, 5-oxo-6-propoxyhexanoate, 7-oxo-8-ethoxyoctanoate and 6-oxo-7-ethoxyheptanoate, such as 4-oxo-5-ethoxyvalerate, 5-oxo-6-propoxyhexanoate, 7-oxo-8-ethoxyoctanoate or 6-oxo-7-ethoxyheptanoate.

[0034] The molar concentration of the carboxylic acid compound containing the ketone carbonyl group in the solution is preferably (0.3-0.8) mol / L, for example, 0.375 or 0.6 mol / L.

[0035] The method for preparing the solution of the carboxylic acid compound containing a ketone carbonyl group preferably includes the following steps: mixing the carboxylic acid compound containing the ketone carbonyl group and a solvent under an inert atmosphere. The inert atmosphere is preferably nitrogen. The mixing temperature is preferably -2 to 2°C, for example, 0°C.

[0036] In this invention, the fluorinated amine compounds preferably include fluorinated amine compounds with 3-8 carbon atoms, more preferably include fluorinated amine compounds with 3-6 carbon atoms, and most preferably include one or more of 3,3-difluoropropylamine, 3,3,4,4-tetrafluorobutylamine, 3,3,4,4,5,5-hexafluoropentylamine and 2,2,3,3,4,4,5,5-octafluorohexylamine, such as 3,3-difluoropropylamine, 3,3,4,4-tetrafluorobutylamine, 3,3,4,4,5,5-hexafluoropentylamine or 2,2,3,3,4,4,5,5-octafluorohexylamine.

[0037] In this invention, the molar ratio of the carboxylic acid compound containing a ketone carbonyl group to the fluorinated amine compound can be (0.5-2):1, preferably (1-1.5):1, for example 1:1.

[0038] In a preferred embodiment, the carboxylic acid compound containing a ketone carbonyl group is 4-oxo-5-ethoxyvalerate, and the fluorinated amine compound is 3,3,4,4-tetrafluorobutylamine. The molar ratio of the 4-oxo-5-ethoxyvalerate and the 3,3,4,4-tetrafluorobutylamine is preferably (0.5-2):1, more preferably (1-1.5):1, for example, 1:1.

[0039] In a preferred embodiment, the carboxylic acid compound containing a ketone carbonyl group is 5-oxo-6-propoxyhexanoic acid, and the fluorinated amine compound is 3,3,4,4,5,5-hexafluoropentylamine. The molar ratio of the 5-oxo-6-propoxyhexanoic acid to the 3,3,4,4,5,5-hexafluoropentylamine is preferably (0.5-2):1, more preferably (1-1.5):1, for example, 1:1.

[0040] In a preferred embodiment, the carboxylic acid compound containing a ketone carbonyl group is 4-oxo-5-methoxyvalerate, and the fluorinated amine compound is 2,2,3,3,4,4,5,5-octafluorohexylamine. The molar ratio of the 4-oxo-5-methoxyvalerate and the 2,2,3,3,4,4,5,5-octafluorohexylamine is preferably (0.5-2):1, more preferably (1-1.5):1, for example, 1:1.

[0041] In a preferred embodiment, the carboxylic acid compound containing a ketone carbonyl group is 4-oxo-5-methoxyvalerate, and the fluorinated amine compound is 3,3-difluoropropylamine. The molar ratio of the 4-oxo-5-methoxyvalerate and the 3,3-difluoropropylamine is preferably (0.5-2):1, more preferably (1-1.5):1, for example, 1:1.

[0042] In a preferred embodiment, the carboxylic acid compound containing a ketone carbonyl group is 7-oxo-8-ethoxyoctanoic acid, and the fluorinated amine compound is 3,3,4,4-tetrafluorobutylamine. The molar ratio of the 7-oxo-8-ethoxyoctanoic acid to the 3,3,4,4-tetrafluorobutylamine is preferably (0.5-2):1, more preferably (1-1.5):1, for example, 1:1.

[0043] In a preferred embodiment, the carboxylic acid compound containing a ketone carbonyl group is 6-oxo-7-ethoxyheptanoic acid, and the fluorinated amine compound is 3,3,4,4-tetrafluorobutylamine. The molar ratio of the 6-oxo-7-ethoxyheptanoic acid to the 3,3,4,4-tetrafluorobutylamine is preferably (0.5-2):1, more preferably (1-1.5):1, for example, 1:1.

[0044] In this invention, the organic base can be of the conventional type in the art, preferably an amine compound and / or a pyridine compound, more preferably one or more of triethylamine, N,N-diisopropylethylamine and pyridine, such as triethylamine, N,N-diisopropylethylamine or pyridine.

[0045] In this invention, the molar number of the organic base can be 1.0%-1.2% of the molar number of the carboxylic acid compound containing the ketone carbonyl group, preferably 1.0%.

[0046] In this invention, the mixture preferably further includes an activator. The activator preferably includes a primary activator and an auxiliary activator.

[0047] The primary activator preferably includes carbodiimide compounds, such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride. The molar amount of the primary activator is preferably 1.0%-1.2% of the molar amount of the carboxylic acid compound containing a ketone carbonyl group, more preferably 1.0%.

[0048] The auxiliary activator preferably includes benzotriazole compounds, such as 1-hydroxybenzotriazole. The molar amount of the auxiliary activator is preferably 1.0%-1.2% of the molar amount of the carboxylic acid compound containing a ketone carbonyl group, more preferably 1.0%.

[0049] The main activator is preferably added 1-3 times, for example 3 times.

[0050] The temperature of the system when the main activator is added can be 0-10℃, for example, 0-5℃.

[0051] In this invention, the reaction temperature can be room temperature, generally 20-30℃.

[0052] In this invention, the reaction time can be 2-12 hours, for example 3, 5, 8 or 12 hours.

[0053] In a preferred embodiment, the method for preparing the mixture of carboxylic acid compound containing ketone carbonyl and fluorinated amine compound includes the following steps: adding an auxiliary activator, a fluorinated amine compound and an organic base sequentially to a solution of carboxylic acid compound containing ketone carbonyl, maintaining the temperature at 0-5°C, and adding the main activator in batches.

[0054] In this invention, after the reaction is completed, a purification step is preferably performed.

[0055] The purification steps preferably include extraction, washing, solvent removal and purification in sequence.

[0056] The extraction solution used for the extraction can be conventional in the art, such as dichloromethane.

[0057] The washing steps can be conventional in the art, and preferably involve washing once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated saline solution.

[0058] The solvent removal step can be conventional in the art, and preferably includes drying with anhydrous sodium sulfate, filtration, and vacuum concentration in sequence.

[0059] The purification method is preferably silica gel column chromatography. The eluent used in the purification is preferably petroleum ether and ethyl acetate. The volume ratio of petroleum ether to ethyl acetate is preferably (1-3):1, for example, 2:1.

[0060] The present invention also provides a dispersant prepared by the preparation method described above.

[0061] The present invention also provides an electrode comprising a current collector and an electrode material layer disposed on at least one surface of the current collector, the electrode material layer comprising a dispersant as described above and a β-phase polyvinylidene fluoride; the mass of the dispersant is 2%-20% of the mass of the β-phase polyvinylidene fluoride.

[0062] In this invention, the electrode is preferably a positive electrode.

[0063] In this invention, the mass of the dispersant is preferably 5%-20% of the mass of the β-phase polyvinylidene fluoride, for example 8%, 10% or 15%.

[0064] In this invention, the β-phase content of the polyvinylidene fluoride in the β phase can be 75%-90%, preferably 78%-88%, for example 86%, 85.5%, 85.4%, 85.2%, 84.8% or 84.1%.

[0065] In this invention, the electrode slurry preferably further includes a conductive agent, a solvent, and an active substance.

[0066] The conductive agent can be of a type conventional in the art, such as Super P.

[0067] The solvent may be of a type conventional in the art, such as polyvinylpyrrolidone.

[0068] The active material can be of conventional types in the art, such as lithium iron phosphate.

[0069] The mass ratio of the active material, the polyvinylidene fluoride and the conductive agent can be (95-99):(1-3):1, for example 97:2:1.

[0070] The present invention also provides a battery comprising the electrodes as described above.

[0071] The positive and progressive effects of this invention are as follows:

[0072] (1) In this invention, the dispersant is cleverly designed to include compounds containing amide groups, compounds containing ketone carbonyl groups and compounds containing fluorine groups; the amide groups and ketone carbonyl groups can synergistically induce PVDF to form an all-trans conformation and promote the formation of the β phase; the fluorine groups can enhance the compatibility between the dispersant and PVDF and further improve the interfacial bonding force.

[0073] (2) Batteries made using electrodes containing this dispersant have excellent electrochemical performance, especially rate performance and cycle performance.

[0074] (3) The dispersant prepared by the method of the present invention has a high yield, is simple and easy to implement, is suitable for industrial production, and has broad application prospects. Attached Figure Description

[0075] Figure 1 The image shows the infrared spectrum of the dispersant prepared in Example 1.

[0076] Figure 2 The infrared spectrum is of the mixture of dispersant and polyvinylidene fluoride in Example 1.

[0077] Figure 3 The infrared spectrum is of the mixture of dispersant and polyvinylidene fluoride in Comparative Example 1. Detailed Implementation

[0078] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0079] Example 1

[0080] (1) In a three-necked flask equipped with a stirrer, a reflux condenser and a constant pressure dropping funnel, add 30 mmol of 4-oxo-5-ethoxyvalerate and 50 mL of dichloromethane, and cool to 0 °C under nitrogen protection;

[0081] (2) Add 1-hydroxybenzotriazole (HOBt, 30 mmol), 3,3,4,4-tetrafluorobutylamine (30 mmol), and triethylamine (30 mmol) to the system sequentially. Keep the temperature at 0-5℃ and slowly add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30 mmol) in three equal batches. After the addition is complete, remove the ice bath and allow the reaction solution to slowly rise to room temperature, and continue stirring for 8 hours.

[0082] (3) TLC monitoring showed that the acid in the raw material had essentially disappeared. After the reaction was complete, 100 mL of ice water was added to the reaction solution for dilution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 2). The organic phases were combined and washed once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent, yielding the crude product.

[0083] (4) The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain 7.2 g of the target product N-(3,3,4,4-tetrafluorobutyl)-4-oxo-5-ethoxypentamide in white solid form, with a yield of 82%, and dispersant 1-N-(3,3,4,4-tetrafluorobutyl)-4-oxo-5-ethoxypentamide was obtained.

[0084] The structural formula of dispersant 1 is: HCF2CF2CH2-CH2-NH-CO-CH2-CH2-CO-CH2-O-CH2CH3;

[0085] Wherein, R1 is a C2 straight-chain alkyl group; R2 is -CH2-CH2-(CF2)2, m is 2; R3 is -CH2-OCH2CH3, n is 2.

[0086] (5) Dissolve the obtained dispersant 1 and PVDF completely in N-methylpyrrolidone (NMP) (the mass ratio of PVDF to NMP is 6:94, and the mass of dispersant 1 is 5% of the mass of PVDF), switch to the revolution / rotation mode, and stir at 1000 rpm for 60 minutes under vacuum to obtain a uniform slurry; add Super P (SP) powder to the above slurry and disperse at 2000 rpm for 30 minutes in a planetary mixer; continue to add lithium iron phosphate (LFP) powder and disperse at 2000 rpm for 120 minutes in a planetary mixer, switch to the revolution / rotation mode, and stir at 500 rpm for 30 minutes under vacuum to obtain a positive electrode slurry; the solid content of the positive electrode slurry is 60%.

[0087] Example 2

[0088] (1) In a three-necked flask equipped with a stirrer, a reflux condenser and a constant pressure dropping funnel, add 30 mmol of 5-oxo-6-propoxyhexanoic acid and 80 mL of dichloromethane, and cool to 0 °C under nitrogen protection.

[0089] (2) Add 1-hydroxybenzotriazole (HOBt, 30 mmol), 3,3,4,4,5,5-hexafluoropentylamine (30 mmol), and triethylamine (30 mmol) to the system sequentially. Keep the temperature at 0-5℃ and slowly add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30 mmol) in three equal batches. After the addition is complete, remove the ice bath and allow the reaction solution to slowly rise to room temperature, and continue stirring for 8 hours.

[0090] (3) TLC monitoring showed that the acid in the raw material had essentially disappeared. After the reaction was complete, 100 mL of ice water was added to the reaction solution for dilution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 2). The organic phases were combined and washed once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent, yielding the crude product.

[0091] (4) The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain 7.2 g of the target product N-(3,3,4,4,5,5-hexafluoropentyl)-5-oxo-6-propoxyhexanamide in white solid form, with a yield of 83.2%, and dispersant 2-N-(3,3,4,4,5,5-hexafluoropentyl)-5-oxo-6-propoxyhexanamide was obtained.

[0092] The structural formula of dispersant 2 is: H(CF2)3CH2-CH2-NH-CO-CH2-CH2-CH2-CO-CH2-O-CH2CH2CH3; wherein, R1 is a C3 straight-chain alkyl group; R2 is -CH2-CH2-(CF2)3, m is 3; R3 is -CH2-OCH2CH2CH3, n is 3.

[0093] (5) Dissolve the obtained dispersant 2 and PVDF completely in NMP (the mass ratio of PVDF to NMP is 6:94, and the mass of dispersant 2 is 5% of the mass of PVDF), switch to the revolution / rotation mode, and stir at 1000 rpm for 60 minutes under vacuum to obtain a uniform slurry; add Super P (SP) powder to the above slurry and disperse at 2000 rpm for 30 minutes in a planetary mixer; continue to add lithium iron phosphate (LFP) powder and disperse at 2000 rpm for 120 minutes in a planetary mixer, switch to the revolution / rotation mode, and stir at 500 rpm for 30 minutes under vacuum to obtain a positive electrode slurry; the solid content of the positive electrode slurry is 60%.

[0094] Example 3

[0095] (1) In a three-necked flask equipped with a stirrer, a reflux condenser and a constant pressure dropping funnel, add 30 mmol of 4-oxo-5-methoxyvalerate and 80 mL of dichloromethane, and cool to 0 °C under nitrogen protection.

[0096] (2) Add 1-hydroxybenzotriazole (HOBt, 30 mmol), 2,2,3,3,4,4,5,5-octafluorohexylamine (30 mmol), and triethylamine (30 mmol) to the system sequentially. Keep the temperature at 0-5℃ and slowly add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30 mmol) in three equal batches. After the addition is complete, remove the ice bath and allow the reaction solution to slowly rise to room temperature, and continue stirring for 8 hours.

[0097] (3) TLC monitoring showed that the acid in the raw material had essentially disappeared. After the reaction was complete, 100 mL of ice water was added to the reaction solution for dilution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 2). The organic phases were combined and washed once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent, yielding the crude product.

[0098] (4) The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain 7.2 g of the target product N-(2,2,3,3,4,4,5,5-octafluorohexyl)-4-oxo-5-methoxypentamide in white solid form, with a yield of 82.8%, and dispersant 3-N-(2,2,3,3,4,4,5,5-octafluorohexyl)-4-oxo-5-methoxypentamide.

[0099] The structural formula of dispersant 3 is: H(CF2)4CH2-CH2-NH-CO-CH2-CH2-CO-CH2-O-CH3; wherein, R1 is a C2 alkyl group; R2 is -CH2-CH2-(CF2)4, m is 4; R3 is -CH2-OCH3, n is 1.

[0100] (5) Dissolve the obtained dispersant 3 and PVDF completely in NMP (the mass ratio of PVDF to NMP is 6:94, and the mass of dispersant 3 is 5% of the mass of PVDF), switch to the revolution / rotation mode, and stir at 1000 rpm for 60 minutes under vacuum to obtain a uniform slurry; add Super P (SP) powder to the above slurry and disperse at 2000 rpm for 30 minutes in a planetary mixer; continue to add lithium iron phosphate (LFP) powder and disperse at 2000 rpm for 120 minutes in a planetary mixer, switch to the revolution / rotation mode, and stir at 500 rpm for 30 minutes under vacuum to obtain a positive electrode slurry; the solid content of the positive electrode slurry is 60%.

[0101] Example 4

[0102] (1) In a three-necked flask equipped with a stirrer, a reflux condenser and a constant pressure dropping funnel, add 30 mmol of 4-oxo-5-ethoxyvalerate and 80 mL of dichloromethane, and cool to 0 °C under nitrogen protection.

[0103] (2) Add 1-hydroxybenzotriazole (HOBt, 30 mmol), 3,3-difluoropropylamine (30 mmol), and triethylamine (30 mmol) sequentially to the system. Keep the temperature at 0-5℃ and slowly add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30 mmol) in three equal batches. After the addition is complete, remove the ice bath, allow the reaction solution to slowly rise to room temperature, and continue stirring the reaction for 8 hours.

[0104] (3) TLC monitoring showed that the acid in the raw material had essentially disappeared. After the reaction was complete, 100 mL of ice water was added to the reaction solution for dilution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 2). The organic phases were combined and washed once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent, yielding the crude product.

[0105] (4) The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain 6.9 g of the target product N-(3,3-difluoropropyl)-4-oxo-5-ethoxypentamide in white solid form, with a yield of 81.1%, and the dispersant 4-N-(3,3-difluoropropyl)-4-oxo-5-ethoxypentamide was obtained.

[0106] The structural formula of dispersant 4 is: HCF2CF2 CH2-CH2-NH-CO-CH2-CO-CH2-O-CH2CH3; wherein, R1 is a C1 alkyl group; R2 is CH2-CH2-(CF2)2, m is 2; R3 is -CH2-OCH2CH3, n is 2.

[0107] (5) Dissolve the obtained dispersant 4 and PVDF completely in NMP (the mass ratio of PVDF to NMP is 6:94, and the mass of dispersant 4 is 5% of the mass of PVDF), switch to the revolution / rotation mode, and stir at 1000 rpm for 60 minutes under vacuum to obtain a uniform slurry; add Super P (SP) powder to the above slurry and disperse at 2000 rpm for 30 minutes in a planetary mixer; continue to add lithium iron phosphate (LFP) powder and disperse at 2000 rpm for 120 minutes in a planetary mixer, switch to the revolution / rotation mode, and stir at 500 rpm for 30 minutes under vacuum to obtain a positive electrode slurry; the solid content of the positive electrode slurry is 60%.

[0108] Example 5

[0109] (1) In a three-necked flask equipped with a stirrer, a reflux condenser and a constant pressure dropping funnel, add 30 mmol of 7-oxo-8-ethoxyoctanoic acid and 80 mL of dichloromethane, and cool to 0°C under nitrogen protection.

[0110] (2) Add 1-hydroxybenzotriazole (HOBt, 30 mmol), 3,3,4,4-tetrafluorobutylamine (30 mmol), and triethylamine (30 mmol) sequentially to the system. Keep the temperature at 0-5℃ and slowly add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30 mmol) in three equal batches. After the addition is complete, remove the ice bath and allow the reaction solution to slowly rise to room temperature, and continue stirring the reaction for 8 hours.

[0111] (3) TLC monitoring showed that the acid in the raw material had essentially disappeared. After the reaction was complete, 100 mL of ice water was added to the reaction solution for dilution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 2). The organic phases were combined and washed once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent, yielding the crude product.

[0112] (4) The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain 7.1 g of the target product N-(3,3,4,4-tetrafluorobutyl)-7-oxo-8-ethoxyoctamide in white solid form, with a yield of 82.1%, and the dispersant 5-N-(3,3,4,4-tetrafluorobutyl)-7-oxo-8-ethoxyoctamide was obtained.

[0113] The structural formula of dispersant 5 is: HCF2CF2 CH2-CH2-NH-CO-(CH2)5-CO-CH2-O-CH2CH3; wherein, R1 is a C5 straight-chain alkyl group; R2 is -CH2-CH2-(CF2)2, m is 2; R3 is -CH2-OCH2CH3, n is 2.

[0114] (5) Dissolve the obtained dispersant 5 and PVDF completely in NMP (the mass ratio of PVDF to NMP is 6:94, and the mass of dispersant 5 is 5% of the mass of PVDF), switch to the revolution / rotation mode, and stir at 1000 rpm for 60 minutes under vacuum to obtain a uniform slurry; add Super P (SP) powder to the above slurry and disperse at 2000 rpm for 30 minutes in a planetary mixer; continue to add lithium iron phosphate (LFP) powder and disperse at 2000 rpm for 120 minutes in a planetary mixer, switch to the revolution / rotation mode, and stir at 500 rpm for 30 minutes under vacuum to obtain a positive electrode slurry; the solid content of the positive electrode slurry is 60%.

[0115] Example 6

[0116] (1) In a three-necked flask equipped with a stirrer, a reflux condenser and a constant pressure dropping funnel, add 30 mmol of 6-oxo-7-ethoxyheptanoic acid and 80 mL of dichloromethane, and cool to 0 °C under nitrogen protection.

[0117] (2) Add 1-hydroxybenzotriazole (HOBt, 30 mmol), 3,3,4,4-tetrafluorobutylamine (30 mmol), and triethylamine (30 mmol) sequentially to the system. Keep the temperature at 0-5℃ and slowly add 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI, 30 mmol) in three equal batches. After the addition is complete, remove the ice bath and allow the reaction solution to slowly rise to room temperature, and continue stirring the reaction for 8 hours.

[0118] (3) TLC monitoring showed that the acid in the raw material had essentially disappeared. After the reaction was complete, 100 mL of ice water was added to the reaction solution for dilution, and the mixture was separated. The aqueous phase was extracted with dichloromethane (30 mL × 2). The organic phases were combined and washed once each with 1M hydrochloric acid solution, saturated sodium bicarbonate solution, and saturated brine solution. The organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to remove the solvent, yielding the crude product.

[0119] (4) The crude product was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 2 / 1, v / v) to obtain 7.0 g of the target product N-(3,3,4,4-tetrafluorobutyl)-6-oxo-7-butoxyheptamide, which was a white solid with a yield of 81.9%, and the dispersant 6-N-(3,3,4,4-tetrafluorobutyl)-6-oxo-7-butoxyheptamide was obtained.

[0120] The structural formula of dispersant 6 is: HCF2CF2 CH2-CH2-NH-CO-(CH2)4-CO-CH2-O-CH2CH3; wherein, R1 is a C4 straight-chain alkyl group; R2 is -CH2-CH2-(CF2)2, m is 2; R3 is -CH2-OCH2CH3, n is 2.

[0121] (5) Dissolve the obtained dispersant 6 and PVDF completely in NMP (the mass ratio of PVDF to NMP is 6:94, and the mass of dispersant 6 is 5% of the mass of PVDF), switch to the revolution / rotation mode, and stir at 1000 rpm for 60 minutes under vacuum to obtain a uniform slurry; add Super P (SP) powder to the above slurry and disperse at 2000 rpm for 30 minutes in a planetary mixer; continue to add lithium iron phosphate (LFP) powder and disperse at 2000 rpm for 120 minutes in a planetary mixer, switch to the revolution / rotation mode, and stir at 500 rpm for 30 minutes under vacuum to obtain a positive electrode slurry; the solid content of the positive electrode slurry is 60%.

[0122] Example 7

[0123] The only difference from Example 1 is that in step (5), the mass of dispersant 1 is 10% of the mass of PVDF.

[0124] Example 8

[0125] The only difference from Example 1 is that in step (5), the mass of dispersant 1 is 20% of the mass of PVDF.

[0126] Comparative Example 1

[0127] The only difference from Example 1 is that in step (5), the mass of dispersant 1 is 0% of the mass of PVDF, that is, no dispersant is added to the positive electrode slurry formulation.

[0128] Comparative Example 2

[0129] The only difference from Example 1 is that 3,3,4,4-tetrafluorobutylamine in step (1) is replaced with butylamine; the dispersant obtained is N-butyl-4-oxo-5-ethoxypentanamide, with the structural formula HCH2CH2 CH2-CH2-NH-CO-CH2-CH2-CO-CH2-O-CH2CH3.

[0130] Comparative Example 3

[0131] The only difference from Example 1 is that in step (5), the mass of dispersant 1 is 1% of the mass of PVDF.

[0132] Comparative Example 4

[0133] The only difference from Example 7 is that in step (5), dispersant 1 is replaced with LIB-D300 acrylate, which is purchased from Shanghai Sanrui Polymer Materials Co., Ltd.

[0134] Example 1: Physicochemical property characterization

[0135] (1) Structural characterization infrared spectroscopy test

[0136] The dispersant prepared in Example 1 was subjected to infrared spectroscopy using a Nicolet iG50 FTIR spectrometer. The testing method was as follows: ATR mode was activated, and the air background was tested. The polyether ester was dropped onto a diamond crystal on the ATR module, and the spectra were measured at 400 cm⁻¹. -1 -4000cm -1 The area was scanned 32 times, with a resolution of 4cm. -1 The result is as follows Figure 1 As shown.

[0137] Figure 1 The infrared spectrum of the dispersant prepared in Example 1 is shown in the figure at 3369 cm⁻¹. -1 It has NH stretching vibration peaks, 2900-3000 cm⁻¹ -1 There is an NH stretching vibration peak at 1454 cm⁻¹. -1 The presence of the -NH-CO- stretching vibration peak at 1674 cm⁻¹ confirms the existence of amide bonds in the dispersant; and the presence of these three peaks verifies the presence of amide bonds in the dispersant. -1 There is an absorption peak near the carbonyl group of a ketone; 1270 cm⁻¹ -1 There is a -CF absorption peak nearby; 1220 cm⁻¹ -1 There is an absorption peak for COC nearby; 1375 cm⁻¹ -1 There is a methyl absorption peak nearby; this proves that the molecular structure of this dispersant does indeed contain characteristic groups such as amide groups, CF groups, ketone carbonyl groups, and ether bonds.

[0138] Infrared spectra of dispersants in other embodiments and Figure 1 resemblance.

[0139] (2) β-phase content test: The dispersant and PVDF in Examples 1-8 and Comparative Examples 1-4 were mixed respectively (the mixing ratios are shown in Table 1 below) to obtain mixtures. The mixtures obtained above were measured by Fourier transform infrared spectroscopy (FTIR) with wavenumbers of 400-4000 cm⁻¹. -1 128 scans were performed. The formula for calculating the β phase is:

[0140]

[0141] Among them, X a Xᵦ refers to the crystallinity of the nonpolar phase (α crystal form); Xᵦ: crystallinity of the polar phase (β crystal form); A a Aᵦ: Vibrational intensity at 760-773 cm⁻¹ (corresponding to the characteristic absorption peak of the α crystal form); Kᵦ: Vibrational intensity at 835-875 cm⁻¹ (corresponding to the characteristic absorption peak of the β crystal form); a A constant with a value of 6.1 × 10⁻⁶. 4 cm² / mol; Kᵦ: constant, with a value of 7.7 × 10⁻⁶. 4 cm² / mol.

[0142] The infrared spectrum of the mixture of dispersant and polyvinylidene fluoride in Example 1 is as follows: Figure 2 The positions and intensities of each peak are shown in Table 1.

[0143] The infrared spectrum of the mixture of dispersant and polyvinylidene fluoride in Comparative Example 1 is as follows: Figure 3 The positions and intensities of each peak are shown in Table 1.

[0144] Table 1

[0145]

[0146] The content test results of the β phase are shown in Table 2.

[0147] Table 2

[0148]

[0149] As shown in Table 2,

[0150] The dispersants in Examples 1-8 showed a higher degree of induction of the β phase in PVDF (β phase content of 78% or more) than the dispersants in Comparative Examples 1-4.

[0151] Comparing Examples 1, 5, and 6, the β-phase induction effect slightly decreased with the increase of the number of carbon atoms in the straight-chain alkyl group.

[0152] Compared with Example 1, when no dispersant was added in Comparative Example 1, the degree of induction of the β phase of PVDF was relatively low, and the β phase content of the obtained PVDF was only 70%.

[0153] Compared with Example 1, when the dispersant in Comparative Example 2 does not contain compounds containing fluorine groups, its induction of the β phase of PVDF is relatively low, indicating that the fluorine-containing segments can significantly enhance the compatibility and interaction between the dispersant and PVDF.

[0154] Compared with Example 1, when the amount of dispersant added in Comparative Example 3 is small (e.g., 1% of PVDF), its induction of the β phase of PVDF is relatively low, and the β phase content of the obtained PVDF is only 76.1%.

[0155] Compared to Example 1, when the dispersant in Comparative Example 4 did not include compounds containing amide groups, compounds containing ketone carbonyl groups, or compounds containing fluorine groups, its induction of the β phase of PVDF was significantly reduced.

[0156] (2) Dispersant volatility test

[0157] The volatility of the dispersants in Examples 1-8 and Comparative Examples 1-4 was tested using thermogravimetric analysis (TGA) at a heating rate of 10 °C / min under a nitrogen atmosphere. The test results are shown in Table 3.

[0158] Table 3

[0159]

[0160] (3) Slurry viscosity and stability test:

[0161] Slurry preparation process:

[0162] The viscosity of the positive electrode slurry in Examples 1-8 and Comparative Examples 1-4 was tested using a Bollerfeld DV2T-LVTJ0 viscometer. The test results are shown in Table 4.

[0163] Table 4

[0164]

[0165] As shown in Table 4, the viscosity stability of the cathode slurry prepared with the dispersants of Examples 1-8 is much higher than that of the cathode slurry prepared with the dispersants of Comparative Examples 1-4.

[0166] Comparing Examples 1, 5, and 6, the stability of the cathode slurry decreased slightly with the increase of the number of carbon atoms in the straight-chain alkyl group. (4) Electrochemical stability

[0167] The dispersants prepared in Examples 1-8 were dissolved in electrolyte (SS-SHRG004, Dongguan Shanshan Battery Materials Co., Ltd.) to prepare test solutions with a concentration of 0.1 mol / L. Their electrochemical stability was tested using linear sweep voltammetry. The results showed that all dispersants exhibited no significant oxidative decomposition below 4.3 V, demonstrating good voltage resistance.

[0168] (5) Electrochemical performance

[0169] Electrode preparation:

[0170] The positive electrode slurries prepared in Examples 1-8 and Comparative Examples 1-4 were coated onto aluminum foil with a wet film thickness of 150 μm, dried at 120°C for 30 minutes, and then vacuum dried at 120°C for 12 hours to completely remove the solvent. Finally, they were compacted using a roller press to a porosity of approximately 40%.

[0171] Assemble button batteries

[0172] The electrode sheet obtained above was vacuum dried, then rolled and punched to a size of 2.01 cm². 2 The positive electrode sheet.

[0173] The negative electrode uses lithium metal sheets, the separator uses Celgard 2400PE film, and the electrolyte uses commercially available products (SS-SHRG004, Dongguan Shanshan Battery Materials Co., Ltd.).

[0174] In a glove box (high-purity Ar atmosphere), the above-mentioned positive electrode, separator and negative electrode are assembled at once, and then the electrolyte (SS-SHRG004, Dongguan Shanshan Battery Materials Co., Ltd.) is injected to obtain a button cell.

[0175] 1) Initial discharge capacity and initial coulombic efficiency

[0176] The button cell was subjected to constant current charge-discharge cycle test at 25℃ and 0.1C, with a charge-discharge voltage of 2.0 to 3.7V. The initial coulombic efficiency was calculated. There was no special test method. The test results are shown in Table 5.

[0177] 2) Rate performance and cycle performance

[0178] The coin cell battery rate and rate performance were tested using a CT3002A.5V 1mA & 10mA 8C1U battery from Wuhan Landian Electronics Co., Ltd. Rate performance = 1C discharge specific capacity / 0.1C discharge specific capacity. The coin cell battery rate was tested and cycled 100 times at 25℃ and 1C. 1C capacity retention after 100 cycles = 1C discharge specific capacity after 100 cycles / initial 1C discharge specific capacity. The test results are shown in Table 5.

[0179] Table 5

[0180]

[0181] The rate performance and cycle performance of each embodiment or comparative example in Table 5 are related to the β phase content of PVDF in Table 2, and are consistent with the trend of the β phase content of PVDF in Table 2.

[0182] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A dispersant, characterized in that, It includes compounds with amide groups, ketone carbonyl groups, and fluorinated methylene chains.

2. The dispersant as described in claim 1, characterized in that, The dispersant has the general formula shown in Formula I: R2-NH-CO-R1-CO-R3 Equation I; in: R1 is a C1-C5 straight-chain alkyl group; R2 is a fluorinated methylene chain with the structure -(CF2). m -(CH2)2-, where m=2-4; R3 is an alkyl chain containing an ether bond, with the structure -CH2-O-(CH2). n - where n = 1-3.

3. The dispersant as described in claim 2, characterized in that, The dispersant satisfies one or more of the following conditions: (1) R1 is a C2-C4 straight-chain alkyl group, such as ethyl or propyl; (2) In R2, m is 3; (3) In R3, n is 2.

4. A method for preparing a dispersant, characterized in that, It includes the following steps: The dispersant is obtained by reacting a mixture of a carboxylic acid compound containing a ketone carbonyl group and a fluorinated amine compound in an organic alkaline environment.

5. The method for preparing the dispersant as described in claim 4, characterized in that, The method for preparing the dispersant satisfies one or more of the following conditions: (1) The carboxylic acid compounds containing ketone carbonyl groups include carboxylic acid compounds that simultaneously contain ketone carbonyl groups and ether bonds, preferably including carboxylic acid compounds with 5-8 carbon atoms that simultaneously contain ketone carbonyl groups and ether bonds, more preferably including one or more of 4-oxo-5-ethoxyvalerate, 5-oxo-6-propoxyhexanoate, 7-oxo-8-ethoxyoctanoate and 6-oxo-7-ethoxyheptanoate, such as 4-oxo-5-ethoxyvalerate, 5-oxo-6-propoxyhexanoate, 7-oxo-8-ethoxyoctanoate or 6-oxo-7-ethoxyheptanoate; (2) The fluorinated amine compounds include fluorinated amine compounds with 3-8 carbon atoms, preferably including fluorinated amine compounds with 3-6 carbon atoms, more preferably including one or more of 3,3-difluoropropylamine, 3,3,4,4-tetrafluorobutylamine, 3,3,4,4,5,5-hexafluoropentylamine and 2,2,3,3,4,4,5,5-octafluorohexylamine, such as 3,3-difluoropropylamine, 3,3,4,4-tetrafluorobutylamine, 3,3,4,4,5,5-hexafluoropentylamine or 2,2,3,3,4,4,5,5-octafluorohexylamine; (3) The molar ratio of the carboxylic acid compound containing a ketone carbonyl group to the fluorinated amine compound is (0.5-2):1, preferably (1-1.5):1, for example 1:1; (4) The organic base is an amine compound and / or a pyridine compound, preferably one or more of triethylamine, N,N-diisopropylethylamine and pyridine, such as triethylamine, N,N-diisopropylethylamine or pyridine; (5) The molar number of the organic base is 1.0%-1.2% of the molar number of the carboxylic acid compound containing the ketone carbonyl group, preferably 1.0%.

6. The method for preparing the dispersant as described in claim 4, characterized in that, The method for preparing the dispersant satisfies one or more of the following conditions: (1) The mixture further includes an activator; the activator preferably includes a main activator and an auxiliary activator; The main activator preferably includes carbodiimide compounds, such as 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; The molar number of the main activator is preferably 1.0%-1.2% of the molar number of the carboxylic acid compound containing the ketone carbonyl group, and more preferably 1.0%. The type of auxiliary activator preferably includes benzotriazole compounds, such as 1-hydroxybenzotriazole; The molar number of the auxiliary activator is preferably 1.0%-1.2% of the molar number of the carboxylic acid compound containing the ketone carbonyl group, and more preferably 1.0%. (2) The reaction temperature is 20-30℃; (3) The reaction time is 2-12h, for example 3, 5, 8 or 12h.

7. A dispersant, characterized in that, It is prepared by any one of the preparation methods described in claims 4-6.

8. An electrode, characterized in that, The electrode includes a current collector and an electrode material layer disposed on at least one surface of the current collector, the electrode material layer comprising a dispersant as described in any one of claims 1-3 and 7 and a β-phase polyvinylidene fluoride; the mass of the dispersant is 2%-20% of the mass of the β-phase polyvinylidene fluoride.

9. The electrode as claimed in claim 8, characterized in that, The electrode satisfies one or more of the following conditions: (1) The mass of the dispersant is 5%-20% of the mass of the β-phase polyvinylidene fluoride, for example 8%, 10% or 15%; (2) The β phase content of the polyvinylidene fluoride of the β phase is 75%-90%, preferably 78%-88%, for example 86%, 85.5%, 85.4%, 85.2%, 84.8% or 84.1%.

10. A battery, characterized in that, It includes the electrode as described in claim 8 or 9.

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