A deformation-resistant negative electrode binder and a method for preparing the same

Abstract

This invention relates to the field of batteries, specifically to an anti-deformation negative electrode binder and its preparation method. It solves the problem that existing negative electrode binders have poor anti-deformation capabilities, leading to structural collapse, rapid capacity decay, and shortened cycle life after long-term cycling. This anti-deformation negative electrode binder uses a binder base material as the main raw material. The binder base material contains multiple active groups that can adsorb and bind to the negative electrode components, achieving tight adhesion and effectively preventing excessive expansion of the negative electrode components. Adding a polyfluorinated organic framework further enhances its electrochemical performance and chemical stability, improving the expansion suppression effect of the negative electrode components and ultimately enhancing the anti-deformation capability of the negative electrode sheet, significantly improving its cycle performance and service life.

Description

Technical Field

[0001] This invention relates to the field of batteries, and more specifically to a deformation-resistant negative electrode binder and its preparation method. Background Technology

[0002] With the surge in demand for high-energy-density lithium-ion batteries from electric vehicles and energy storage systems, silicon is considered the core of next-generation anode materials due to its extremely high theoretical specific capacity. However, silicon undergoes a massive volume expansion of over 300% during charge and discharge, which can easily lead to anode structural collapse, rapid capacity decay, and shortened cycle life.

[0003] As a key component that adheres active materials and conductive agents to the current collector and maintains the integrity of the electrode structure, the performance of the binder is crucial. Traditional polyvinylidene fluoride (PVDF) binders are linear polymers that bond through relatively weak van der Waals forces, making them prone to failure under the drastic volume changes of silicon. Although some novel binders (such as polyacrylic acid PAA, sodium alginate SA, and sodium carboxymethyl cellulose CMC) have been studied, which improve adhesion through stronger hydrogen bonding, they are mostly brittle materials with insufficient elasticity, unable to effectively absorb and dissipate the stress generated by silicon expansion, and cracks still appear after long-term cycling.

[0004] Therefore, developing a deformation-resistant negative electrode binder and its preparation method is of great practical significance. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the present invention aims to provide a deformation-resistant negative electrode binder and its preparation method, which solves the problem that the existing negative electrode binders have poor deformation resistance, which makes the negative electrode structure prone to collapse, capacity decay and cycle life shortening after long-term cycling.

[0006] The objective of this invention can be achieved through the following technical solutions: In a first aspect, this application provides a deformation-resistant negative electrode binder, comprising the following components in parts by weight: 100-110 parts of binder base material, 9-25 parts of polyfluorinated organic framework; The polyfluorinated organic framework is prepared by the following steps: Step a1: Add terephthalaldehyde and concentrated sulfuric acid to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir the reaction at 20-25℃ and 300-400 r / min for 20-30 min. Then add N-bromosuccinimide and continue stirring at 70-75℃ for 4-6 h. After the reaction is complete, cool the reaction product to room temperature and add it to ice water. Then filter under vacuum and add the filter cake to dichloromethane. Wash the filter cake 2-3 times with saturated sodium bicarbonate solution and saturated brine solution. Dry the filter cake with anhydrous magnesium sulfate and then filter under vacuum. Remove the solvent by rotary evaporation to obtain brominated terephthalaldehyde. Step a2: Add terephthalaldehyde bromide, 3,5-bis(trifluoromethylphenylboronic acid), tetra(triphenylphosphine)palladium, sodium carbonate, deionized water, and toluene to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir the reaction at 20-25℃ and a stirring rate of 300-400 r / min for 20-30 min. Then raise the temperature to 80-85℃ and continue stirring for 20-30 h. After the reaction is complete, cool the reaction product to room temperature and extract it 2-3 times with ethyl acetate. Combine the extracts and wash them 2-3 times with saturated brine. Dry with anhydrous magnesium sulfate and then filter under vacuum. Remove the solvent by rotary evaporation of the filtrate to obtain polyfluoroterephthalaldehyde. Step a3: Add polyfluorinated terephthalaldehyde, melamine, n-butanol, o-dichlorobenzene, and acetic acid solution to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir the reaction at 20-25℃ and 300-400 r / min for 20-30 min. Then raise the temperature to 110-120℃ and continue stirring for 36-48 h. After the reaction is complete, cool the reaction product to room temperature, then remove the solvent by rotary evaporation. Then soak in distilled water, tetrahydrofuran, and acetone for 10-15 h in sequence. Finally, place it in a vacuum drying oven and dry at 80-90℃ for 2-4 h to obtain the polyfluorinated organic framework.

[0007] In a preferred embodiment of the present invention, the ratio of terephthalaldehyde, concentrated sulfuric acid and N-bromosuccinimide used in step a1 is 1g: 15-20mL: 2.8-3.2g.

[0008] In a preferred embodiment of the present invention, the concentrated sulfuric acid in step a1 has a mass fraction of 98%.

[0009] In a preferred embodiment of the present invention, the ratio of the amounts of terephthalaldehyde bromide, 3,5-bis(trifluoromethyl)phenylboronic acid, tetra(triphenylphosphine)palladium, sodium carbonate, deionized water and toluene in step a2 is 10 mmol: 21-23 mmol: 0.15-0.25 g: 25-30 mmol: 10-15 mL: 50-60 mL.

[0010] In a preferred embodiment of the present invention, the ratio of the polyfluoroalkyl terephthalaldehyde, melamine, n-butanol, o-dichlorobenzene and acetic acid solution in step a3 is 15 mmol: 10 mmol: 60-70 mL: 60-70 mL: 20-25 mL.

[0011] In a preferred embodiment of the present invention, the molar concentration of the acetic acid solution in step a3 is 5-6 mol / L.

[0012] In a preferred embodiment of the present invention, the adhesive base material is prepared by the following steps: Butyl acrylate, acrylamide, hydroxyethyl acrylate, α-linolenic acid, and methacryloyloxypropyltrimethoxysilane were added to a three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred for 10-20 minutes at a temperature of 20-25℃ and a stirring rate of 300-400 r / min. Then, an azobisisobutyronitrile-xylene solution was added dropwise while stirring, with the dropping rate controlled at 1-3 drops / s. After the addition was completed, the temperature was raised to 60-70℃ and the reaction was continued with stirring for 2-4 hours. After the reaction was completed, the reaction product was cooled to room temperature and then poured into methanol. The mixture was then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried for 2-4 hours at a temperature of 50-60℃ to obtain the binder base material.

[0013] In a preferred embodiment of the present invention, the ratio of butyl acrylate, acrylamide, hydroxyethyl acrylate, α-linolenic acid, methacryloyloxypropyltrimethoxysilane, and azobisisobutyronitrile-xylene solution is 40 mmol: 10-12 mmol: 10-12 mmol: 10-20 mmol: 5-25 mmol: 80-90 mL.

[0014] In a preferred embodiment of the present invention, the mass fraction of the azobisisobutyronitrile-xylene solution is 0.5-1.3%.

[0015] Secondly, this application provides a method for preparing a deformation-resistant negative electrode binder, comprising the following steps: Step 1: Weigh out 100-110 parts of the adhesive base and 9-25 parts of the polyfluorinated organic framework according to the weight ratio, and set aside; Step 2: Add the binder base material and polyfluorinated organic framework to the mixer and mix evenly. Then pulverize to 50-100 mesh to obtain the deformation-resistant negative electrode binder.

[0016] The beneficial effects of this invention are: This invention discloses an anti-deformation negative electrode binder and its preparation method. The binder binder and a polyfluorinated organic framework are added to a mixer and mixed evenly, then pulverized to obtain the anti-deformation negative electrode binder. The binder binder uses the binder binder as the main raw material. The binder binder contains multiple active groups that can adsorb and bind to the negative electrode components, achieving tight adhesion and effectively preventing excessive expansion of the negative electrode components. Adding a polyfluorinated organic framework enhances its electrochemical performance and chemical stability, further improving the expansion suppression effect of the negative electrode components, ultimately enhancing the anti-deformation ability of the negative electrode sheet and significantly improving its cycle performance and service life.

[0017] In the process of preparing the deformation-resistant negative electrode binder, a binder base material was first prepared. This binder base material was formed by polymerization of butyl acrylate, acrylamide, hydroxyethyl acrylate, α-linolenic acid, and methacryloyloxypropyltrimethoxysilane as monomers. The molecular structure of this binder base material contains a large number of alkenyl, amino, hydroxyl, and siloxane groups, giving it high reactivity and enabling it to bond tightly with the negative electrode components, thus improving the stability of the negative electrode. Furthermore, the multiple alkenyl groups on the α-linolenic acid can enhance the cross-linking degree of the binder base material, further improving the internal density of the negative electrode and significantly enhancing its chemical stability.

[0018] In the process of preparing the deformation-resistant negative electrode binder, a polyfluorinated organic framework was also prepared. N-bromosuccinimide was used as a brominating agent to bromate terephthalaldehyde, introducing bromine atoms onto the benzene ring of terephthalaldehyde to obtain brominated terephthalaldehyde. The reaction of brominated terephthalaldehyde with 3,5-bis(trifluoromethyl)phenylboronic acid resulted in the bromine atoms on the brominated terephthalaldehyde reacting with the boric acid groups on 3,5-bis(trifluoromethyl)phenylboronic acid, introducing a large number of fluorine atoms to obtain polyfluorinated terephthalaldehyde. The polyfluorinated terephthalaldehyde... The reaction of formaldehyde and melamine allows the aldehyde group on the polyfluorinated terephthalaldehyde to form a Schiff base structure with the amino group on the melamine, resulting in a Schiff base covalent organic framework structure and a polyfluorinated organic framework. This polyfluorinated organic framework is characterized by rigidity, porosity, and high surface area, which is conducive to rapid ion transport and provides a buffering effect, thus enabling it to adapt to volume changes during charging and discharging. Moreover, the large number of fluorine atoms can significantly improve its chemical stability, thereby enhancing the stability of the negative electrode and endowing it with excellent deformation resistance.

[0019] Eliminate the following numbers: (27, 32, 63, 69, 01, 07, 14, 16, 22, 23, 24, 26, 36, 46, 47, 50, 61, 62, 72) Select numbers (74 13 19 65 77 36 32 06, 10, 18, 22, 24, 26, 40, 42, 44, 54, 66 29, 35, 37, 43, 51, 53, 57, 65, 77) Remove the eliminated numbers from the number selection. Eliminate the following numbers: (27, 32, 63, 69, 01, 07, 14, 16, 22, 23, 24, 26, 36, 46, 47, 50, 61, 62, 72) Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1:

[0022] This embodiment describes a method for preparing a deformation-resistant negative electrode binder, comprising the following steps: Step S1: Add 1g of terephthalaldehyde and 15mL of 98% concentrated sulfuric acid to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir for 20min at 20℃ and 300r / min. Then add 2.8g of N-bromosuccinimide and continue stirring at 70℃ for 4h. After the reaction is complete, cool the reaction product to room temperature and add it to ice water. Then filter under vacuum and add the filter cake to dichloromethane. Wash twice with saturated sodium bicarbonate solution and saturated brine, then dry with anhydrous magnesium sulfate. Then filter under vacuum and evaporate the filtrate by rotary evaporation to remove the solvent, to obtain terephthalaldehyde bromide. Step S2: 10 mmol of terephthalaldehyde bromide, 21 mmol of 3,5-bis(trifluoromethylphenylboronic acid), 0.15 g of tetra(triphenylphosphine)palladium, 25 mmol of sodium carbonate, 10 mL of deionized water, and 50 mL of toluene were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 20 °C and a stirring rate of 300 r / min for 20 min. Then, the temperature was raised to 80 °C and the mixture was stirred for another 20 h. After the reaction was completed, the reaction product was cooled to room temperature and then extracted twice with ethyl acetate. The extracts were combined and washed twice with saturated brine. The mixture was then dried with anhydrous magnesium sulfate and vacuum filtered. The solvent was removed by rotary evaporation of the filtrate to obtain polyfluoroterephthalaldehyde. Step S3: 15 mmol of polyfluoro-based terephthalaldehyde, 10 mmol of melamine, 60 mL of n-butanol, 60 mL of o-dichlorobenzene, and 20 mL of acetic acid solution with a molar concentration of 5 mol / L were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 20 °C and a stirring rate of 300 r / min for 20 min. Then, the temperature was raised to 110 °C and the stirring was continued for 36 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. Then, the product was soaked in distilled water, tetrahydrofuran, and acetone for 10 h in sequence. Finally, it was placed in a vacuum drying oven and dried at 80 °C for 2 h to obtain the polyfluoro-based organic framework. Step S4: Add 40 mmol butyl acrylate, 10 mmol acrylamide, 10 mmol hydroxyethyl acrylate, 10 mmol α-linolenic acid, and 5 mmol methacryloyloxypropyltrimethoxysilane to a three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel, and gas delivery tube. Purge with nitrogen for protection and stir at 20°C and 300 r / min for 10 min. Then, while stirring, add 80 mL of 0.5% azobisisobutyronitrile-xylene solution dropwise at a rate of 1 drop / s. After the addition is complete, raise the temperature to 60°C and continue stirring for 2 h. After the reaction is complete, cool the reaction product to room temperature and pour it into methanol. Then, vacuum filter the mixture and place the filter cake in a vacuum drying oven at 50°C for 2 h to obtain the binder base material. Step S5: Weigh out 100 parts of the adhesive base and 9 parts of the polyfluorinated organic framework according to the weight ratio, and set aside; Step S6: Add the binder base material and polyfluorinated organic framework to the mixer and mix evenly. Then pulverize to 50 mesh to obtain the deformation-resistant negative electrode binder.

[0023] Example 2:

[0024] This embodiment describes a method for preparing a deformation-resistant negative electrode binder, comprising the following steps: Step S1: Add 1g of terephthalaldehyde and 18mL of 98% concentrated sulfuric acid to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 22℃ and 350r / min for 25min. Then add 3g of N-bromosuccinimide and continue stirring at 72℃ for 5h. After the reaction is complete, cool the reaction product to room temperature and add it to ice water. Then filter under vacuum and add the filter cake to dichloromethane. Wash the filter cake twice with saturated sodium bicarbonate solution and saturated brine solution, then dry it with anhydrous magnesium sulfate. Then filter under vacuum and evaporate the filtrate by rotary evaporation to remove the solvent, to obtain terephthalaldehyde bromide. Step S2: 10 mmol of terephthalaldehyde bromide, 22 mmol of 3,5-bis(trifluoromethylphenylboronic acid), 0.2 g of tetra(triphenylphosphine)palladium, 28 mmol of sodium carbonate, 12 mL of deionized water, and 55 mL of toluene were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 22 °C and a stirring rate of 350 r / min for 25 min. Then, the temperature was raised to 82 °C and the mixture was stirred for another 25 h. After the reaction was completed, the reaction product was cooled to room temperature and then extracted twice with ethyl acetate. The extracts were combined and washed twice with saturated brine. The mixture was then dried with anhydrous magnesium sulfate and vacuum filtered. The solvent was removed by rotary evaporation of the filtrate to obtain polyfluoroterephthalaldehyde. Step S3: 15 mmol of polyfluoro-based terephthalaldehyde, 10 mmol of melamine, 65 mL of n-butanol, 65 mL of o-dichlorobenzene, and 22 mL of acetic acid solution with a molar concentration of 5.5 mol / L were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 22 °C and a stirring rate of 350 r / min for 25 min. Then, the temperature was raised to 115 °C and the stirring was continued for 42 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. Then, the product was soaked in distilled water, tetrahydrofuran, and acetone for 12 h in sequence. Finally, it was placed in a vacuum drying oven and dried at 85 °C for 3 h to obtain the polyfluoro-based organic framework. Step S4: Add 40 mmol butyl acrylate, 11 mmol acrylamide, 11 mmol hydroxyethyl acrylate, 15 mmol α-linolenic acid, and 15 mmol methacryloyloxypropyltrimethoxysilane to a three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel, and gas delivery tube. Purge with nitrogen for protection and stir at 22°C and 350 r / min for 15 min. Then, while stirring, add 85 mL of 0.9% azobisisobutyronitrile-xylene solution dropwise at a rate of 2 drops / s. After the addition is complete, raise the temperature to 65°C and continue stirring for 3 h. After the reaction is complete, cool the reaction product to room temperature and pour it into methanol. Then, vacuum filter the mixture and place the filter cake in a vacuum drying oven at 55°C for 3 h to obtain the binder base material. Step S5: Weigh out 105 parts of the adhesive base and 17 parts of the polyfluorinated organic framework according to the weight ratio, and set aside; Step S6: Add the binder base material and polyfluorinated organic framework to the mixer and mix evenly. Then pulverize to 75 mesh to obtain the deformation-resistant negative electrode binder.

[0025] Example 3:

[0026] This embodiment describes a method for preparing a deformation-resistant negative electrode binder, comprising the following steps: Step S1: Add 1g of terephthalaldehyde and 20mL of 98% concentrated sulfuric acid to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 25℃ and 400r / min for 30min. Then add 3.2g of N-bromosuccinimide and continue stirring at 75℃ for 6h. After the reaction is complete, cool the reaction product to room temperature and add it to ice water. Then filter under vacuum and add the filter cake to dichloromethane. Wash the filter cake three times with saturated sodium bicarbonate solution and saturated brine solution. Dry the filter cake with anhydrous magnesium sulfate and then filter under vacuum. Remove the solvent by rotary evaporation to obtain terephthalaldehyde bromide. Step S2: 10 mmol of terephthalaldehyde bromide, 23 mmol of 3,5-bis(trifluoromethylphenylboronic acid), 0.25 g of tetra(triphenylphosphine)palladium, 30 mmol of sodium carbonate, 15 mL of deionized water, and 60 mL of toluene were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 25 °C and a stirring rate of 400 r / min for 30 min. Then, the temperature was raised to 85 °C and the mixture was stirred for another 30 h. After the reaction was completed, the reaction product was cooled to room temperature and then extracted three times with ethyl acetate. The extracts were combined and washed three times with saturated brine. The product was then dried with anhydrous magnesium sulfate and vacuum filtered. The solvent was removed by rotary evaporation of the filtrate to obtain polyfluoroterephthalaldehyde. Step S3: 15 mmol of polyfluoro-based terephthalaldehyde, 10 mmol of melamine, 70 mL of n-butanol, 70 mL of o-dichlorobenzene, and 25 mL of acetic acid solution with a molar concentration of 6 mol / L were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 25 °C and a stirring rate of 400 r / min for 30 min. Then, the temperature was raised to 120 °C and the stirring was continued for 48 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. Then, the product was soaked in distilled water, tetrahydrofuran, and acetone for 15 h in sequence. Finally, it was placed in a vacuum drying oven and dried at 90 °C for 4 h to obtain the polyfluoro-based organic framework. Step S4: Add 40 mmol butyl acrylate, 12 mmol acrylamide, 12 mmol hydroxyethyl acrylate, 20 mmol α-linolenic acid, and 25 mmol methacryloyloxypropyltrimethoxysilane to a three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel, and gas delivery tube. Purge with nitrogen for protection and stir at 25°C and 400 r / min for 20 min. Then, while stirring, add 90 mL of 1.3% azobisisobutyronitrile-xylene solution dropwise at a rate of 3 drops / s. After the addition is complete, raise the temperature to 70°C and continue stirring for 4 h. After the reaction is complete, cool the reaction product to room temperature and pour it into methanol. Then, vacuum filter the mixture and place the filter cake in a vacuum drying oven at 60°C for 4 h to obtain the binder base material. Step S5: Weigh out 110 parts of the adhesive base and 25 parts of the polyfluorinated organic framework according to the weight ratio, and set aside; Step S6: Add the binder base material and polyfluorinated organic framework to the mixer and mix evenly. Then pulverize to 100 mesh to obtain the deformation-resistant negative electrode binder.

[0027] Comparative Example 1: The comparative example is Solvay PVDF 6008 from the United States.

[0028] Comparative Example 2: This comparative example illustrates a method for preparing a deformation-resistant negative electrode binder, comprising the following steps: 40 mmol butyl acrylate, 12 mmol acrylamide, 12 mmol hydroxyethyl acrylate, 20 mmol α-linolenic acid, and 25 mmol methacryloyloxypropyltrimethoxysilane were added to a three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 25 °C and a stirring rate of 400 r / min for 20 min. Then, 90 mL of a 1.3% (w / w) azobisisobutyronitrile-xylene solution was added dropwise while stirring, with the dropping rate controlled at 3 drops / s. After the addition was completed, the temperature was raised to 70 °C and the reaction was continued with stirring for 4 h. After the reaction was completed, the reaction product was cooled to room temperature and then poured into methanol. The mixture was then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at 60 °C for 4 h to obtain the deformation-resistant negative electrode binder.

[0029] Comparative Example 3: This comparative example illustrates a method for preparing a deformation-resistant negative electrode binder, comprising the following steps: Step S1: 15 mmol of terephthalaldehyde, 10 mmol of melamine, 70 mL of n-butanol, 70 mL of o-dichlorobenzene, and 25 mL of acetic acid solution with a molar concentration of 6 mol / L were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 25 °C and a stirring rate of 400 r / min for 30 min. Then, the temperature was raised to 120 °C and the stirring was continued for 48 h. After the reaction was completed, the reaction product was cooled to room temperature, and the solvent was removed by rotary evaporation. Then, the product was soaked in distilled water, tetrahydrofuran, and acetone for 15 h in sequence. Finally, it was placed in a vacuum drying oven and dried at 90 °C for 4 h to obtain the organic framework. Step S2: 40 mmol butyl acrylate, 12 mmol acrylamide, 12 mmol hydroxyethyl acrylate, 20 mmol α-linolenic acid, and 25 mmol methacryloyloxypropyltrimethoxysilane were added to a three-necked flask equipped with a stirrer, thermometer, constant pressure dropping funnel, and gas delivery tube. Nitrogen gas was introduced for protection, and the mixture was stirred at 25°C and a stirring rate of 400 r / min for 20 min. Then, while stirring, 90 mL of a 1.3% (w / w) azobisisobutyronitrile-xylene solution was added dropwise at a rate of 3 drops / s. After the addition was complete, the temperature was raised to 70°C and the reaction was continued for 4 h. After the reaction was completed, the reaction product was cooled to room temperature and then poured into methanol. The mixture was then vacuum filtered, and the filter cake was placed in a vacuum drying oven and dried at 60°C for 4 h to obtain the binder base material. Step S3: Weigh out 110 parts of the binder base and 25 parts of the organic skeleton according to the weight ratio, and set aside; Step S4: Add the binder base material and organic skeleton to the mixer and mix evenly. Then pulverize to 100 mesh to obtain the deformation-resistant negative electrode binder.

[0030] Silicon powder, Super P, and the binders of Examples 1-3 and Comparative Examples 1-3 were mixed with solvent (NMP for Comparative Example 1 and DMF for the rest) in a ratio of 7:2:1 to obtain a uniform slurry. The slurry was then coated onto copper foil, vacuum dried, and then cut to obtain a negative electrode sheet. Using lithium metal sheets as the counter electrode, the negative electrode, counter electrode, separator, electrolyte, gasket, spring sheet and battery case are assembled into a CR2032 coin cell. The separator is Celgard 2400 and the electrolyte is 1M LiPF6 (the volume ratio of methyl ethyl carbonate, ethylene carbonate and diethyl carbonate is 1:1:1).

[0031] The performance of the CR2032 button cells was tested, and the results are shown in the table below:

[0032] Referring to the data in the table above, and based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the anti-deformation negative electrode binder of this application has a high capacity retention rate and a low active material thickness expansion rate, indicating that the anti-deformation negative electrode binder can improve the anti-deformation ability of the electrode sheet and enhance its cycle stability.

[0033] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0034] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A deformation-resistant negative electrode binder, characterized in that, Includes the following components by weight: 100-110 parts of binder base material, 9-25 parts of polyfluorinated organic framework; The polyfluorinated organic framework is prepared by the following steps: Step a1: Terephthalaldehyde and concentrated sulfuric acid are stirred and reacted, then N-bromosuccinimide is added and the reaction is continued. After the reaction is completed, the reaction product is cooled and then added to ice water. After vacuum filtration, the filter cake is added to dichloromethane, then washed and dried. After vacuum filtration, the filtrate is evaporated by rotary evaporation to obtain terephthalaldehyde bromide. Step a2: Terephthalaldehyde bromide, 3,5-bis(trifluoromethylphenylboronic acid), tetra(triphenylphosphine)palladium, sodium carbonate, deionized water and toluene were stirred and reacted. After the reaction was completed, the reaction product was cooled and then extracted. The extract was washed, dried and then vacuum filtered. The filtrate was then evaporated by rotary evaporation to obtain polyfluoroterephthalaldehyde. Step a3: The polyfluorinated terephthalaldehyde, melamine, n-butanol, o-dichlorobenzene and acetic acid solution were stirred and reacted. After the reaction was completed, the reaction product was cooled to room temperature, then evaporated by rotary evaporation, then soaked and dried to obtain the polyfluorinated organic framework.

2. The anti-deformation negative electrode binder according to claim 1, characterized in that, The ratio of terephthalaldehyde, concentrated sulfuric acid, and N-bromosuccinimide used in step a1 is 1g: 15-20mL: 2.8-3.2g.

3. The deformation-resistant negative electrode binder according to claim 1, characterized in that, The concentrated sulfuric acid in step a1 has a mass fraction of 98%.

4. The deformation-resistant negative electrode binder according to claim 1, characterized in that, The ratio of the amounts of brominated terephthalaldehyde, 3,5-bis(trifluoromethyl)phenylboronic acid, tetra(triphenylphosphine)palladium, sodium carbonate, deionized water and toluene in step a2 is 10 mmol: 21-23 mmol: 0.15-0.25 g: 25-30 mmol: 10-15 mL: 50-60 mL.

5. The anti-deformation negative electrode binder according to claim 1, characterized in that, The ratio of the polyfluoroalkyl terephthalaldehyde, melamine, n-butanol, o-dichlorobenzene and acetic acid solution used in step a3 is 15 mmol: 10 mmol: 60-70 mL: 60-70 mL: 20-25 mL.

6. The anti-deformation negative electrode binder according to claim 1, characterized in that, The molar concentration of the acetic acid solution in step a3 is 5-6 mol / L.

7. The deformation-resistant negative electrode binder according to claim 1, characterized in that, The adhesive base material is prepared by the following steps: Butyl acrylate, acrylamide, hydroxyethyl acrylate, α-linolenic acid, and methacryloyloxypropyltrimethoxysilane were stirred and reacted. Then, an azobisisobutyronitrile-xylene solution was added dropwise and the reaction was continued with stirring. After the reaction was completed, the reaction product was cooled and then poured into methanol. After vacuum filtration, the filter cake was dried to obtain the binder base material.

8. The deformation-resistant negative electrode binder according to claim 7, characterized in that, The ratio of butyl acrylate, acrylamide, hydroxyethyl acrylate, α-linolenic acid, methacryloyloxypropyltrimethoxysilane, and azobisisobutyronitrile-xylene solution is 40 mmol: 10-12 mmol: 10-12 mmol: 10-20 mmol: 5-25 mmol: 80-90 mL.

9. The deformation-resistant negative electrode binder according to claim 7, characterized in that, The mass fraction of the azobisisobutyronitrile-xylene solution is 0.5-1.3%.

10. A method for preparing the anti-deformation negative electrode binder as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Weigh out 100-110 parts of the adhesive base and 9-25 parts of the polyfluorinated organic framework according to the weight ratio, and set aside; Step 2: Add the binder base material and polyfluorinated organic framework to the mixer and mix evenly. Then pulverize to 50-100 mesh to obtain the deformation-resistant negative electrode binder.

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