CN114920868A

CN114920868A - Fluoropolymer capable of improving adhesive force, preparation process and application

Info

Publication number: CN114920868A
Application number: CN202210713282.4A
Authority: CN
Inventors: 刘懿平; 赵帅; 马磊; 王刚; 纪学顺; 孙家宽
Original assignee: Wanhua Chemical Sichuan Battery Material Technology Co Ltd; Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Sichuan Battery Material Technology Co Ltd; Wanhua Chemical Group Co Ltd
Priority date: 2022-06-22
Filing date: 2022-06-22
Publication date: 2022-08-19
Anticipated expiration: 2042-06-22
Also published as: CN114920868B

Abstract

The invention discloses a fluoropolymer for improving adhesive force, a preparation process and application thereof, wherein the fluoropolymer is prepared by suspension polymerization of the following components in the presence of an initiator, a polymerization stabilizer and optionally other additives; a component a: vinylidene fluoride; and (b) component b: fluorine-containing or non-fluorine-containing comonomers; and (b) component c: an ethylenically unsaturated silane; wherein the amount of the component b is 0-10wt% of the addition amount of the component a; the component c is used in an amount of 0.01 to 5wt% of the amount of the component a. The ethylenically unsaturated silane of the present invention as a comonomer can improve the adhesion of the fluoropolymer to the substrate while maintaining good electrochemical stability.

Description

Fluoropolymer capable of improving adhesive force, preparation process and application

Technical Field

The invention relates to a fluorine-containing polymer, in particular to a fluorine-containing polymer capable of improving adhesive force, a preparation process and application.

Background

Polyvinylidene fluoride (PVDF) is mainly characterized by having both C-F and C-H bonds in the family of fluorine-containing polymer materials, wherein the C-F bond provides structural stability, excellent mechanical properties, aging resistance, high and low temperature resistance, insulation, chemical resistance, sun resistance and flame retardance, and the C-H bond provides solubility, so that the PVDF is easy to process. Therefore, the PVDF resin is particularly suitable for being prepared into coatings and viscous glue solutions, such as coatings, lithium battery diaphragm coatings, photovoltaic back plate coatings, lithium battery positive pole adhesives and the like.

Polyvinylidene fluoride is known in the art as being suitable as a binder for use in the manufacture of electrodes, particularly positive electrodes, for use in the manufacture of composite separators, and/or for coating porous separators for use in non-aqueous based electrochemical devices such as batteries. Fluoropolymers are traditionally used in applications requiring special properties, such as low surface energy, high resistance to chemical attack, aging resistance and electrochemical stability. However, these advantageous properties also make the fluoropolymer difficult to handle and limit its application. For example, the lack of polar functional groups on the fluoropolymer makes it difficult to adhere to the substrate, difficult to promote crosslinking, difficult to provide sites for subsequent chemical modification, difficult to wet with water, and difficult to increase hydrophilicity.

Therefore, it is necessary to modify the molecular segment of polyvinylidene fluoride by copolymerization or grafting, and a polar functional group capable of improving the performance of the fluoropolymer is added to the molecular segment of the polymer by various ways to enhance the special performance of the fluoropolymer, such as improving the adhesion of the fluoropolymer to polar substrates such as metal and glass. However, since fluorine atoms or fluorine-containing radicals have superior electronegativity and anti-intrusion characteristics, it is difficult to directly add functional group monomers to a polymer backbone being polymerized, especially in a random intercalation manner.

For example, patent CN101679563B discloses a process for the preparation of a linear semicrystalline fluoropolymer by copolymerizing vinylidene fluoride with 0.05-10% of a hydrophilic (meth) acrylic monomer (most preferably acrylic acid or hydroxyethyl acrylate) and continuously feeding an aqueous solution of the (meth) acrylic comonomer at a polymerization pressure of 4.43Mpa above the VDF critical pressure, the (meth) acrylic comonomer randomly distributed units in the final fluoropolymer being at least 40%. The fluorine-containing polymerization adhesive has the advantages of obviously improved bonding strength and thermal stability, and is suitable for lithium ion battery adhesives. Although the method can improve the adhesive property of the vinylidene fluoride copolymer to a certain extent, the (methyl) acrylic acid monomer has a serious tendency of easy self-polymerization, the grafting rate is low, and ester bonds in the acrylate are unstable under acidic or alkaline conditions, so that the application range and the application field of the method are limited.

Patent CN108883608B discloses that the fluoropolymer prepared by copolymerizing vinylidene fluoride with trifluoroethylene and an adhesion promoting monomer can improve the adhesion of metal surfaces or glass. Wherein the adhesion promoting monomer is comprised of a non-perfluorinated vinyl or vinylidene monomer having at least one weak acid or weak acid precursor functional group, such as dialkyl vinylphosphonates, bis-vinylphosphonates, and (2-trifluoromethyl) acrylic acid, and the like, wherein the functional monomer is preferably used in an amount of 0.2 to 0.9%. Although the invention creatively uses other fluorine-containing monomers and weakly acidic vinyl monomers to carry out copolymerization modification on the vinylidene fluoride, theoretically, certain performances of the vinylidene fluoride copolymer can be improved, obviously, the copolymerization of a plurality of fluorine-containing and non-fluorine-containing monomers can be influenced by the super electronegativity and anti-intrusion characteristics of fluorine atoms or fluorine-containing free radicals, functional monomer units are difficult to be uniformly polymerized in a polymer skeleton, and the actual use effect is severely limited.

Patent CN104725544B discloses that vinylidene fluoride and at least one fluorine atom modified acrylate monomer are copolymerized (such as trifluoroethyl 2-methacrylate, trifluoromethyl 2-methacrylate, methyl 1, 1-difluoro-2-methacrylate or methyl 2-trifluoromethyl methacrylate, etc.), and the copolymer has a higher average molecular weight, a moderate molecular weight distribution, a higher melting point, and better thermodynamics and bonding properties, and is used as a binder for lithium ion batteries. Although the adhesive property of the vinylidene fluoride copolymer is improved to a certain extent, the fluorine atom modified acrylate monomer has the characteristics of difficult preparation, high price and the like, so that the large-scale use and popularization of the fluorine atom modified acrylate monomer are difficult.

There are also many other patents describing methods for improving the cohesion of vinylidene fluoride polymers, such as patent US2020190239a1, which modify the copolymerization of vinylidene fluoride with acrylate monomers and obtain vinylidene fluoride polymers further comprising recurring units derived from (meth) acrylic monomers, exhibiting good thermal stability, by means of a process which allows precise process control, without sudden heat generation, causing uncontrolled reaction temperatures exceeding the set point. The patent US2013273424a1 adopts a suspension polymerization process, and the comonomer is a carboxyl-containing monomer, such as carboxyethyl acrylate, etc., so that the polymer has higher metal substrate adhesion. Patent US7241817B2 describes the grafting of maleic anhydride onto vinylidene fluoride homopolymers or copolymers; patents WO2013110740a1 and US7351498B2 describe that fluoropolymers are functionalized by monomer grafting or copolymerization; patent US5415958A discloses the copolymerization of vinylidene fluoride with unsaturated dibasic acid monoester polar monomers, introducing carbonyl groups into the PVDF backbone to improve its adhesion to different substrates. However, these methods have some problems which are more or less difficult to avoid, especially the copolymerization of vinylidene fluoride with other polar monomers, which are difficult to copolymerize with each other due to the different reaction characteristics and poor compatibility of the two different types of monomers, and the polymerization rate and distribution are also not optimistic.

In addition, patent CN111925471A discloses a silane modified fluoroethyl ester polymer used as a lithium battery binder and a preparation method thereof, wherein a perfluoro vinyl ester compound and a silane compound are copolymerized (the molar ratio is 0.5-5: 1), so that a block copolymer with a silane soft segment structure being in mutual match with a perfluoro alkenyl ester hard segment structure is prepared, the structure and the function of the polymer are enriched due to the synergistic effect between the soft and hard molecular chains, the hard segment fluoroethyl ester structure is used as a framework to endow the polymer with strong mechanical property and cohesiveness, and the soft segment silane is used as a buffering agent to accommodate the huge volume change of silicon particles, so that the flexibility and the film forming property of the polymer molecular chains are improved, and the stability of the electrochemical property of a silicon-based lithium ion battery is facilitated. However, the product can only be used as a silicon-based lithium battery cathode material binder, and the prepared fluoroethyl ester polymer has small molecular weight (the number of copolymerization units is less than or equal to 20), poor mechanical property, heat resistance, solvent resistance and the like, and cannot replace PVDF (polyvinylidene fluoride) to be used in a lithium battery cathode binder.

Aiming at the problem that the vinylidene fluoride polymer still needs to be modified so as to improve the adhesive force of the vinylidene fluoride polymer on polar base materials such as metal, glass and the like, the invention provides a fluorine-containing polymer and a preparation process thereof.

Disclosure of Invention

In order to solve the technical problems, the invention firstly provides a preparation process of the fluoropolymer with improved adhesive force.

The present inventors have found through continuous studies that the prior art has not mentioned a method of preparing a modified fluoropolymer by copolymerizing an ethylenically unsaturated silane compound as a comonomer with vinylidene fluoride in an aqueous solution by a suspension polymerization method. Surprisingly, ethylenically unsaturated silanes as comonomers can improve the adhesion of fluoropolymers to substrates while maintaining good electrochemical stability compared to other functionalized or non-functionalized fluoropolymers.

As another aspect of the present invention, the present invention also provides a fluoropolymer produced by the foregoing production process.

As another aspect of the present invention, the present invention also provides a use of the fluoropolymer produced by the aforementioned production process.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a preparation process of an adhesion-improving fluoropolymer, wherein the fluoropolymer is prepared by suspension polymerization of the following components in the presence of an initiator, a polymerization stabilizer and optionally other auxiliary agents;

a component a: vinylidene fluoride;

and (b) component b: fluorine-containing or non-fluorine-containing comonomers;

and (c) component: an ethylenically unsaturated silane;

wherein, the component b is used in an amount of 0 to 10wt%, preferably 0 to 5wt% of the addition amount of the component a; component c is used in an amount of 0.01 to 5wt%, preferably 0.1 to 3 wt%, based on the amount of component a added.

In a preferred embodiment of the invention, the ethylenically unsaturated silane in component c contains at least one vinyl, allyl or acryloxy group attached to the silicon atom, and at least one Si — O bond;

preferably, the ethylenically unsaturated silane is selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriisopropenoxysilane, vinylmethyldiacetoxysilane, vinyltriacetoxysilane, allyltrimethoxysilane, one or more of allyl methyl dimethoxy silane, allyl triethoxy silane, methacryloxypropyl trimethoxy silane, methacryloxypropyl triethoxy silane, and methacryloxypropyl methyl dimethoxy silane, preferably at least one of vinyl trimethoxy silane, vinyl triethoxy silane, vinyl-tris (2-methoxyethoxy) silane, and methacryloxypropyl trimethoxy silane.

More preferably, the ethylenically unsaturated silane is at least one of vinyltrimethoxysilane (Ailquest A-171, Meiji commercial brand), vinyltriethoxysilane (Ailquest A-151, Meiji commercial brand), vinyl-tris (2-methoxyethoxy) silane (Ailquest A-172, Meiji commercial brand), methacryloxypropyltrimethoxysilane (Ailquest A-174, Meiji commercial brand), in accordance with the contemplation of the present invention.

It should be noted that, in the preparation process of the fluorine-containing polymer, the ethylenically unsaturated silane may be fed at one time to the bottom of the polymerization vessel, or may be fed to the polymerization reaction system in a small amount, continuously or in portions, either alone or together with other monomers and auxiliaries. The aim is to ensure that the ethylenically unsaturated silane reacts with the vinylidene fluoride monomer in an expected manner to achieve the expected use effect.

While the process of the present invention is generally described for the suspension polymerization of vinylidene fluoride, one skilled in the art will recognize that similar polymerization techniques may be applied to produce vinylidene fluoride copolymers with other fluorine-containing or fluorine-free comonomers in the hope of altering the mechanical properties of the fluoropolymer, such as tensile strength, alkali resistance, and adhesion properties. But generally the amount of vinylidene fluoride in the fluoropolymer should be not less than 80 wt% so as not to affect the excellent properties of the fluoropolymer such as chemical resistance, weatherability, and heat resistance.

In a preferred embodiment of the invention, in component b, the fluorine-containing comonomer is selected from one or more of Vinyl Fluoride (VF), trifluoroethylene (TrFE), Tetrafluoroethylene (TFE), Chlorotrifluoroethylene (CTFE), 2,3,3, 3-tetrafluoropropene, Hexafluoropropylene (HFP), Hexafluoroisobutylene (HFIB), Perfluorobutylethylene (PFBE), pentafluoropropene, 3,3, 3-trifluoro-1-propene, 2-trifluoromethyl-3, 3, 3-trifluoropropene, fluorinated vinyl ethers; preferably, the fluorinated vinyl ether is one or more of perfluoromethyl vinyl ether (PMVE), perfluoroethyl vinyl ether (PEVE), perfluoropropyl vinyl ether (PPVE), perfluorobutyl vinyl ether (PBVE);

in the component b, the non-fluorine-containing comonomer is an ethylenic unsaturated monomer, preferably one or more of olefine acids, olefine acid esters, olefine esters, unsaturated nitriles and vinyl aromatic compounds, more preferably one or more of acrylic acid, methacrylic acid, itaconic acid, maleic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinylene carbonate, dimethyl maleate, diethyl maleate, di-n-propyl maleate, diisopropyl maleate, di-2-methoxyethyl maleate, dimethyl fumarate, diethyl fumarate, di-n-propyl fumarate, diisopropyl fumarate, acrylonitrile, styrene, vinyl toluene, alpha-methyl styrene.

The fluoropolymers of the present invention are preferably prepared in aqueous solution by suspension polymerization, although one skilled in the art may apply other polymerization methods (e.g., emulsion polymerization) by routine adjustment to obtain similar products according to the protocols provided herein.

The polymeric stabilizer is used for the purpose of improving dispersibility of vinylidene fluoride and other fluorine-containing or non-fluorine-containing comonomers in water, and in a preferred embodiment of the present invention, the polymeric stabilizer is selected from one or more of celluloses, polyvinyl alcohol, polyethylene glycol, polyacrylic acid, preferably one or more of methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose;

preferably, the addition amount of the polymerization stabilizer is 0.01-1.5% of the addition amount of the vinylidene fluoride.

For a better and more concise description of the present invention, a detailed description of the specific process for preparing the fluoropolymer of the present invention by suspension polymerization is provided below.

A specific preparation process of a fluorine-containing polymer comprises the following steps:

(a) adding deionized water, a polymerization stabilizer and optionally a chain transfer agent into a polymerization reactor, stirring and mixing uniformly, and introducing nitrogen to remove oxygen;

(b) adding an initiator into a polymerization reactor, adding vinylidene fluoride, ethylenically unsaturated silane and optionally other fluorine-containing or non-fluorine-containing comonomers, heating and raising the temperature to start polymerization;

(c) continuously adding the rest of the polymerization monomers, the initiator and optionally the chain transfer agent as required, and keeping the polymerization temperature and the polymerization pressure stable in the required range;

(d) when the addition of the polymerization monomer is finished and the polymerization pressure is less than a set value, the polymerization reaction is finished to prepare the fluorine-containing polymer dispersion liquid;

(e) degassing, washing, filtering and drying are carried out as required to obtain the required fluorine-containing polymer.

The polymerization reactor described in the present invention may be appropriately selected from known polymerization reactors within the range of conditions capable of achieving the suspension polymerization of the present embodiment, including a high-pressure spherical tank, a high-pressure horizontal tank, and a high-pressure vertical tank, wherein the aspect ratio of the polymerization reactor is as small as possible, preferably L/D is less than 2, and more preferably L/D is less than 1.5, in order to ensure the heat transfer and mass transfer effects of the polymerization reaction. In addition, the stirring mode in the polymerization reactor can be one of three-blade inclined paddles, four-blade inclined paddles, anchor type paddles, frame type paddles and helical ribbon type paddles.

In a preferred embodiment of the invention, the initiator is an organic peroxide initiator, preferably diisopropyl peroxydicarbonate, diethyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, 2' -azobis (2, 4-dimethylvaleronitrile), 2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile), tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-amyl peroxypivalate, dibenzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxymaleate, dicumyl peroxide, cumyl hydroperoxide, tert-butyl peroxyacetate, 2' -di (tert-butylperoxy) butane, tert-butylperoxycumene, cumyl peroxide, di (tert-butylperoxy) butane, di (tert-butyl-n-butyl-n-butyl-oxide, di (tert-butyl-n-butyl-n-propyl-oxide, di (tert-butyl-n-butyl-o-n-propyl-oxide), di-butyl-n-butyl-n-oxide, di-butyl-n-butyl-n-oxide, n-butyl-n-butyl-oxide, n-butyl-n-butyl-2, n-butyl-n-butyl-2, n-butyl-n-butyl-n-2, n-butyl-n-butyl-n-butyl-n-butyl-n-butyl-n, n-butyl-n-, One or more of t-butyl peroxyisopropyl carbonate;

preferably, the addition amount of the initiator is 0.01-2%, preferably 0.1-1% of the addition amount of the vinylidene fluoride.

In a preferred embodiment of the invention, the further auxiliaries comprise optionally pH regulators, chain transfer agents.

The chain transfer agent is used for the purpose of adjusting the molecular weight of the resulting fluoropolymer, and may be suitably selected from known compounds capable of being used for adjusting the molecular weight of the fluoropolymer, and is generally selected from, but not limited to, oxygen-containing compounds such as alcohols, carbonates, ketones, esters, and ethers; halogenated hydrocarbons such as chlorohydrocarbons, hydrochlorocarbons, chlorofluorocarbons and hydrochlorofluorocarbons; alkanes such as ethane and propane, and the like. In the invention, the chain transfer agent is preferably one of diethyl carbonate, ethyl acetate and diethyl malonate, and the addition amount of the chain transfer agent is 0.01-1% of the addition amount of the vinylidene fluoride.

In addition, a pH adjusting agent may optionally be included in the polymerization mixture to maintain a controlled pH throughout the polymerization reaction, generally the pH is preferably controlled in the range of about 4 to 8 to minimize the production of undesirable color in the product. The pH adjusting agent may include organic acids and alkali metal salts thereof, inorganic acids and alkali metal salts thereof, and preferred pH adjusting agents in the practice of the present invention include phosphates and acetates. Wherein the phosphate salt may be a salt of phosphoric acid or a mixture of salts thereof.

In general, the polymerization reactor is required to be purged with oxygen in the empty stage or after the addition of the polymerization assistant, and the oxygen content is preferably controlled to 20ppm or less, more preferably 10ppm or less by performing nitrogen substitution a plurality of times in a negative pressure atmosphere.

In the polymerization system of the present invention, it is known to add an appropriate amount of water sufficient to form a suspension, preferably such an amount that the solid content of the vinylidene fluoride dispersion obtained by the polymerization is 20 to 50%, preferably 20 to 40%.

In a preferred embodiment of the present invention, the polymerization temperature is 40 to 100 ℃ and the pressure is 3.0 to 15.0MPa gauge.

In the embodiment provided by the present invention, the pressure in the polymerization reactor is sufficiently above the critical pressure (4.38MPa) of vinylidene fluoride by raising the temperature in the reactor to the polymerization initiation temperature, typically at the maximum in the polymerization reaction. Therefore, vinylidene fluoride in the vinylidene fluoride-containing monomer is mainly used for polymerization in a supercritical fluid state, and the pressure in the reaction system generally decreases as the vinylidene fluoride-containing monomer is used for polymerization, so that the vinylidene fluoride monomer generally needs to be continuously supplemented to maintain the stability of the pressure in the polymerization reaction kettle. When the pressure in the reactor at the time of heating the reaction system to the polymerization initiation temperature is too high, a vessel having high pressure resistance may be required, and when the pressure is too low, the polymerization reaction time may be prolonged, and the productivity may be lowered. The pressure in the reactor at the time when the reaction system is heated to the initial polymerization temperature is preferably 3MPa or more, and more preferably 4.4MPa or more, from the viewpoint of shortening the reaction time. In addition, the pressure is preferably 15MPa or less, and more preferably 13MPa or less, for example, from the viewpoint of reducing the cost of the polymerization reactor. The pressure may be adjusted depending on various factors such as the supply amount of vinylidene fluoride and comonomer, the initial polymerization temperature, and the monomer density.

Meanwhile, the polymerization initiation temperature may be suitably determined within a temperature range sufficient for bringing vinylidene fluoride in the reactor into a supercritical state. Within this range, when the polymerization initiation temperature is too low, the reaction time of suspension polymerization becomes long, and thus the productivity of the vinylidene fluoride polymer may be low, and when the polymerization initiation temperature is too high, the pressure of the reaction system of suspension polymerization may be high, and a reactor having higher pressure resistance may be required. The polymerization initiation temperature is preferably 40 ℃ or higher, and more preferably 45 ℃ or higher, from the viewpoint of improving the productivity of the vinylidene fluoride polymer. From the viewpoint of suppressing the rise in pressure of the reaction system, the polymerization initiation temperature is preferably 100 ℃ or lower, and more preferably 70 ℃.

In the present invention, the end point control of the suspension polymerization is appropriately selected in consideration of the balance between the reduction of the amount of the unreacted monomer and the prolongation of the polymerization time (i.e., the productivity of the product polymer). For example, the end point of the suspension polymerization can be determined by sampling the reaction product, and by the temperature rise in the reaction system and the pressure fluctuation caused thereby.

In the preparation process provided by the invention, the fluorine-containing polymer is obtained in the form of powder, and the powder is obtained by dehydrating, washing and drying polymer slurry after suspension polymerization is finished. According to the preparation process provided by the invention, the reaction efficiency can be improved, and the polymerization time can be shortened. Specifically, the polymerization time from the time point when the starting material is fed to the reactor and the polymerization initiation temperature is reached to the end of the polymerization is preferably within 20 hours, more preferably within 15 hours.

The invention also provides an adhesion-promoting fluoropolymer prepared by the process as described above.

The present invention also provides the use of the fluoropolymer having improved adhesion, prepared by the process described above, in an electrode binder for a non-aqueous electrolyte secondary battery, in particular, in a positive electrode binder for a non-aqueous electrolyte secondary battery.

The present invention also includes an electrode binder composition for a nonaqueous electrolyte secondary battery comprising the fluoropolymer, the electrode active material, the nonaqueous solvent and the like provided above, and a method for producing an electrode for a nonaqueous electrolyte secondary battery obtained by coating the electrode binder composition for a nonaqueous electrolyte secondary battery on a metal current collector and drying the same. According to the needs, the method for testing the electrode for the nonaqueous electrolyte secondary battery mainly comprises the peeling strength of the electrode binder composition for the nonaqueous electrolyte secondary battery on the metal current collector.

The electrode active material is not particularly limited, and conventionally known electrode active materials for negative electrodes and active materials for positive electrodes can be used. The negative electrode active material may be a carbon material, a silicon material, a metal/alloy material, a metal oxide, or the like, and among them, preferred are carbon materials including artificial graphite, natural graphite, non-graphitizable carbon, and the like. One kind of carbon material may be used alone, or two or more kinds may be used. As the positive electrode active material, a lithium-based positive electrode active material containing lithium, such as lithium cobaltate, lithium manganate, lithium iron phosphate, and nickel cobalt manganese ternary material, is generally used. The active ingredient content of the electrode adhesive composition is 0.5-10 parts by mass, preferably 1-5 parts by mass, of the fluorine-containing polymer, and 90-99.5 parts by mass, preferably 95-99 parts by mass, of the active material.

The electrode binder composition for a nonaqueous electrolyte secondary battery further contains a nonaqueous solvent, with which a fluorine-containing polymer is dissolved, and may be selected from one or more of N-methyl-2-pyrrolidone, dimethylformamide, N-dimethylacetamide, N-dimethyl sulfoxide, hexamethylphosphoramide, dioxane, tetrahydrofuran, tetramethylurea, triethyl phosphate, trimethyl phosphate, acetone, methyl ethyl ketone, tetrahydrofuran, and the like. The amount of the nonaqueous solvent to be used is generally 4 to 100 times, preferably 6 to 50 times, the amount of the fluorine-containing polymer, and within this range, the solution viscosity of the electrode composition becomes moderate, and handling becomes easy.

The electrode binder composition for a nonaqueous electrolyte secondary battery may further contain a conductive aid in addition to the fluoropolymer, the nonaqueous solvent and the electrode active material to improve the electrochemical performance of the electrode composition. The conductive auxiliary is generally selected from one or more of carbon substances such as carbon black, carbon nanotubes, graphite fine powder and graphite fibers, and metal fine powder or metal fibers such as nickel and aluminum. The conductive assistant is usually 0.02 to 4 times, more preferably 0.1 to 2 times the amount of the fluorine-containing polymer.

The method for producing the electrode binder composition for a nonaqueous electrolyte secondary battery is not particularly limited as long as the components are mixed by a known method, and the order of mixing the components is not particularly limited. In the case where the electrode active material is added to the electrode binder composition, the electrode active material may be directly added to the electrode binder composition, or the electrode active material may be added to the nonaqueous solvent and stirred and mixed to obtain the electrode binder composition.

The present invention also includes a method for manufacturing an electrode for a nonaqueous electrolyte secondary battery, which is obtained by coating the electrode binder composition for a nonaqueous electrolyte secondary battery on a metal current collector and drying the same. The metal current collector is a base material of the electrode, is a terminal for taking out electricity, and is made of iron, stainless steel, copper, aluminum, nickel, titanium, and the like, preferably, aluminum foil is used as the metal current collector, and the thickness of the metal current collector is usually 5 to 100 μm, preferably 5 to 20 μm. The coating method of the electrode composition may be selected from a wire bar coater, a blade coater, a roll coater, and the like, and the electrode composition is coated on at least one surface, preferably both surfaces, of the current collector. The drying temperature of the electrode composition is preferably 50 to 150 ℃, the drying time is preferably 30 to 300 minutes, and the pressure during drying is not particularly limited, and is usually carried out under atmospheric pressure or reduced pressure. In addition, after the electrode composition is dried, the composition may be subjected to a pressing treatment to increase the electrode energy density.

The present invention also includes a method for testing an electrode for a nonaqueous electrolyte secondary battery, which mainly includes testing the peel strength of an electrode binder composition for a nonaqueous electrolyte secondary battery on a metal current collector.

Detailed Description

The present invention is further illustrated by the following specific examples, which are intended to be illustrative of the invention and are not to be construed as limiting the scope of the invention.

The main test methods involved in the following embodiments are as follows:

<1> method for measuring molecular weight of polymer

The molecular weight of the polymer is tested by a liquid gel chromatograph, and the related testing instrument and method are as follows: sample preparation: dissolving 5g of sample in 5mL of DMF solution, ultrasonically dissolving at normal temperature, and filtering by using a 0.45-micron organic filter membrane to obtain a sample with the concentration of 1 mg/mL; mobile phase: DMF; flow rate: 1 mL/min; detector temperature: 36 ℃; an injection system: 717plus auto-sampler from Waters; injection volume: 250 mu L; a pump: vortes Corp No gradient Pump model 515; type of chromatographic column: three in total, namely WAT.044226, WAT.054466 and WAT.044223; a detector: vortex refractive index model 2414; data acquisition and processing software: wottish Empower.

<2> crystallinity test method

Performing DSC test in N2 atmosphere by using differential scanning calorimeter (DSC, Mettler-Torlo), heating to 200 deg.C at a speed of 10 deg.C/min, and maintaining the temperature for 10min to eliminate thermal history; the temperature was reduced to-80 ℃ at the same rate and then increased at the same rate to determine the melting behavior. The area of the exothermic peak of crystal melting is closely related to the crystallinity, the melting enthalpy delta Hf is calculated according to the area of the melting peak of a heating DSC curve, and the crystallinity of the polymer is calculated according to the following formula:

X＝△Hf/△Hc*100％

where Δ Hf is the melting enthalpy of the test sample, and Δ Hc is the enthalpy value when the polyvinylidene fluoride is completely crystallized, and it is known from the literature that Δ Hc is 104.76J/g.

<3> rotational viscosity test

Accurately weighing 10.28g of fluoropolymer sample in a 250mL beaker, then weighing 100mL of N-methylpyrrolidone in the beaker by using a pipette, stirring for 120min by using a magnetic stirring device at 500r/min, adjusting to the test temperature of 30 +/-0.5 ℃, ensuring that the time fully reaches the test temperature, selecting a No. 3 rotor and a rotation speed of 20r/min by using a Brookfield DV3THA viscometer, putting the rotor into a measurement container, completely immersing, starting an instrument, measuring the viscosity of the sample after the instrument is stabilized, reading and recording the test result, and performing parallel test to obtain an average value twice.

<4> production of electrode for nonaqueous electrolyte secondary battery

5g of the fluoropolymer prepared was added to 100g N-methylpyrrolidone and stirred at high speed until the fluoropolymer was completely dissolved. Then 3.75g of ultra fine carbon powder Super P, 1.25g of carbon nanotubes were added to the solution and mixed uniformly using a mechanical stirrer. Then 240g of electrode active material (nickel-cobalt-manganese ternary material) is added into the mixture, and the mixture is mixed, defoamed and stood at high speed to obtain the pasty electrode binder composition for the secondary battery, which has the viscosity and fineness meeting the requirements, and has no oil stain, bubbles and suspended particles in appearance. The obtained electrode binder composition for a secondary battery was then uniformly coated on an aluminum foil with a wet thickness of 350 μm by a coater, heated in a vacuum oven at 120 ℃ for 150 minutes, and compacted by a roll press to obtain a coating-containing electrode for a non-aqueous electrolyte secondary battery.

<5> bond Strength test

The nonaqueous electrolyte secondary battery prepared in <4> was cut into a strip-shaped electrode sheet of 20cm × 2.5cm, the strip-shaped electrode sheet was bonded to a rigid aluminum plate using a double-sided adhesive (the double-sided adhesive was coated on the side of the strip-shaped electrode sheet containing the coating), and a peel test was performed by fixing the rigid aluminum plate at one end and the strip-shaped electrode sheet at the other end using a tensile tester with a GOTECH model of AI-7000-LA. The test standard was ISO 4624 adhesion pull-off test, the peel angle was 180 °, and the displacement rate of the jaws was set to 100mm/min, to determine the peel strength between the electrode adhesive composition for a nonaqueous electrolyte secondary battery and the metal current collector (aluminum foil).

<6> test of cycle Performance of Battery

In an argon atmosphere glove box which meets the requirements of environmental standards, 30 parts by mass of ethylene carbonate, 20 parts by mass of diethyl carbonate and 45 parts by mass of ethyl methyl carbonate are uniformly mixed, and 5.0 parts by mass of lithium hexafluorophosphate is added into the mixture to prepare an electrolyte; the diaphragm adopts a 12 mu m polyethylene base film and a 4 mu m ceramic coating; the electrode for a nonaqueous electrolyte secondary battery (as a positive electrode), the electrolyte solution, the separator, and the lithium sheet manufactured as described above were assembled by a usual assembly method to obtain a pseudo lithium ion battery (half battery). The prepared lithium ion battery was subjected to cycle performance testing using an electrochemical workstation at a current density of 0.5C. The capacity retention rate of the battery after 100 cycles was calculated using the following formula:

capacity retention (%) after 100 cycles was the discharge capacity after 100 cycles/the discharge capacity after the first cycle.

[ example 1 ]

At room temperature, 4480g of deionized water, 2.5g of hydroxypropyl methylcellulose (HPMC, Shandong Hedada chemical product brand HEADCEL75HD100) as a polymerization stabilizer and 3.6g of diethyl carbonate as a chain transfer agent (DEC, Jinan Pulai chemical Co., Ltd.) were put into a high-pressure polymerization kettle with an effective volume of 10 liters, and stirred until the rotation speed reaches 600rpm, and the bottom liquid was uniformly mixed. Oxygen was removed by nitrogen displacement under vacuum (oxygen content < 20ppm), and then 3.0g of t-butyl peroxypivalate (TBPP, Kannos technologies, Hubei), 2560g of vinylidene fluoride, and 0.8g of vinyltrimethoxysilane (Ailquest A-171, Mach Corp.) were added as an initiator. The temperature was raised to 50 ℃ to start the polymerization. In the reaction process, the temperature is reduced by circulating water, 1200g of 1 percent vinyl trimethoxy silane (Ailquest A-171, Ma diagram) aqueous solution is continuously added after the reaction temperature is stable, the reaction pressure is maintained at 9.0Mpa, 200g of 2.5 percent tert-butyl peroxypivalate and 3.6 percent diethyl carbonate aqueous dispersion are continuously added, and the stirring speed is gradually adjusted according to the liquid level change in a polymerization kettle. After the reaction raw materials are added, the reaction temperature is continuously kept at 50 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 2 ]

At room temperature, 4350g of deionized water, 1.0g of polyethylene glycol 1000 (Beijing Yinuoka Tech Co., Ltd.) as a polymerization stabilizer, 1.8g of hydroxypropyl methylcellulose (HPMC, Shandong He Hada chemical product brand number HEADCEL75HD100) and 3.6g of diethyl carbonate (DEC, Ji nan Lai Hua chemical Co., Ltd.) as a chain transfer agent were put into a high-pressure polymerization reactor having an effective volume of 10 liters, stirred at a rotation speed of 500rpm, and the bottom liquid was mixed uniformly. Oxygen was removed by nitrogen displacement under vacuum (oxygen content < 20ppm), and 3.0g of t-butyl peroxypivalate (TBPP, Kannos technologies, Hubei) as an initiator, 2710g of vinylidene fluoride, and 2.0g of methacryloxypropyltrimethoxysilane (Ailquest A-174, Ma., USA) were added. The temperature was raised to 50 ℃ to start the polymerization. During the reaction, the temperature is reduced by circulating water, 1350g of 2% methacryloxypropyltrimethoxysilane (Ailquest A-174 in America) aqueous solution is continuously added after the reaction temperature is stable, the reaction pressure is maintained at 9.0Mpa, 220g of 3.0% tert-butyl peroxypivalate and 3.6% diethyl carbonate aqueous dispersion are continuously added, and the stirring speed is gradually adjusted according to the liquid level change in a polymerization kettle. After the reaction raw materials are added, the reaction temperature is continuously kept at 50 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 3 ]

At room temperature, 4620g of deionized water, 4.8g of hydroxypropyl methylcellulose (HPMC, shandong hada chemical product brand HEADCEL75HD100), and 2.1g of diethyl carbonate (DEC, ju, junan plel chemical limited) as a chain transfer agent were put into a high-pressure polymerization kettle having an effective volume of 10 liters, and stirred until the rotation speed reached 600rpm, so as to uniformly mix the bottom liquid. Under vacuum condition, nitrogen is introduced for a plurality of times to displace and remove oxygen (oxygen content is less than 20ppm), and then 2.5g of initiator tert-amyl peroxypivalate (TAPP, Zibo Zhenghua assistant Co., Ltd.), 2800g of vinylidene fluoride and 3.5g of vinyl triethoxysilane (Ailquest A-151, a U.S. Megaku) are added. The temperature was raised to 45 ℃ to start the polymerization. In the reaction process, the temperature is reduced by circulating water, 1050g of 3% vinyl triethoxysilane (Ailquest A-151, Mayer diagram) aqueous solution is continuously added after the reaction temperature is stable, the reaction pressure is maintained at 8.4Mpa, 240g of aqueous dispersion containing 2.5% tert-amyl peroxypivalate and 1.6% diethyl carbonate is continuously supplemented, and the stirring speed is gradually adjusted according to the liquid level change in a polymerization kettle. After the reaction raw materials are added, the reaction temperature is kept at 45 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 4 ] A method for producing a polycarbonate

At room temperature, 4750g of deionized water, 2.4g of polyvinyl alcohol PVA17-88 (Beijing Yinuoka Tech Co., Ltd.), 1.5g of hydroxypropyl methylcellulose (HPMC, Shandong Hechada chemical product brand number HEADPEL 75HD100) and 3.0g of chain transfer agent diethyl carbonate (DEC, Jinan Leihua chemical Co., Ltd.) were put into a high-pressure polymerization reactor having an effective volume of 10 liters, stirred at a rotation speed of 500rpm, and the bottom liquid was mixed uniformly. Oxygen is removed by nitrogen displacement under vacuum conditions (oxygen content is less than 20ppm), and then 2.5g of tert-amyl peroxypivalate (TAPP, Zibozhen Hua assistant Co., Ltd.), 2440g of vinylidene fluoride and 4.6g of vinyl-tris (2-methoxyethoxy) silane (Ailquest A-172, Mayer diagram, USA) are added. The temperature was raised to 45 ℃ to start the polymerization. In the reaction process, the temperature is reduced by circulating water, 1260g of a 4% vinyl triethoxysilane (Ailquest A-151, Mayer diagram) aqueous solution is continuously added after the reaction temperature is stable, the reaction pressure is maintained at 8.4Mpa, 300g of an aqueous dispersion containing 2.5% tert-amyl peroxypivalate and 1.6% diethyl carbonate is continuously supplemented, and the stirring speed is gradually adjusted according to the liquid level change in a polymerization kettle. After the reaction raw materials are added, the reaction temperature is kept at 45 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 5 ]

At room temperature, 4450g of deionized water, 3.0g of hydroxypropyl methylcellulose (HPMC, Shandong Hauda chemical product brand HEADCEL75HD100) as a polymerization stabilizer and 2.5g of diethyl carbonate (DEC, Jinan Polilai chemical Co., Ltd.) as a chain transfer agent were put into a high-pressure polymerization kettle with an effective volume of 10 liters, and stirred until the rotation speed was 500rpm, so that the bottom liquid was uniformly mixed. Oxygen was removed by nitrogen displacement under vacuum (oxygen content < 20ppm), and then 3.0g of t-butyl peroxypivalate (TBPP, Hubei Carnoss technologies, Ltd.), 2560g of vinylidene fluoride, 30g of acrylic acid, and 1.5g of vinyltrimethoxysilane (Ailquest A-171, Ma., USA) were added as an initiator. The temperature was raised to 50 ℃ to start the polymerization. In the reaction process, the temperature is reduced by circulating water, 1200g of 2% vinyl trimethoxy silane (Ailquest A-171, Mayer diagram) aqueous solution is continuously added after the reaction temperature is stable, the reaction pressure is maintained at 9.0Mpa, 200g of aqueous dispersion containing 2.5% tert-butyl peroxypivalate and 3.6% diethyl carbonate is continuously added, and the stirring speed is gradually adjusted according to the liquid level change in a polymerization kettle. When the reaction raw materials are supplemented, the reaction temperature is kept at 50 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 6 ]

At room temperature, 4560g of deionized water, 1.5g of polyethylene glycol 1000 (Beijing Yinuoka science and technology Co., Ltd.) as a polymerization stabilizer, 2.4g of hydroxypropyl methylcellulose (HPMC, Shandong He Hada chemical product brand number HEADCEL75HD100) and 1.5g of diethyl carbonate (DEC, Ji nan Lai Hua chemical Co., Ltd.) as a chain transfer agent were put into a high-pressure polymerization reactor having an effective volume of 10 liters, stirred at a rotation speed of 500rpm, and the bottom liquid was uniformly mixed. Oxygen was removed by nitrogen displacement under vacuum (oxygen content < 20ppm), and then 3.0g of t-butyl peroxypivalate (TBPP, Kanus technologies, Hubei), 2640g of vinylidene fluoride, 56g of hydroxyethyl methacrylate, and 1.0g of methacryloxypropyltrimethoxysilane (Ailquest A-174, Ma., USA) were added as an initiator. The temperature was raised to 50 ℃ to start the polymerization. Cooling by circulating water in the reaction process, continuously adding 1160g of 1.5% of methacryloxypropyltrimethoxysilane (Ailquest A-174 in Ma of America) aqueous solution after the reaction temperature is stable, maintaining the reaction pressure at 9.0Mpa, continuously supplementing 250g of 3.0% of tert-butyl peroxypivalate and 2.5% of diethyl carbonate aqueous dispersion liquid, and gradually adjusting the stirring speed according to the liquid level change in a polymerization kettle. After the reaction raw materials are added, the reaction temperature is continuously kept at 50 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 7 ] A method for producing a polycarbonate

At room temperature, 4720g of deionized water, 3.6g of hydroxypropyl methylcellulose (HPMC, yatohoheda chemical product brand HEADCEL75HD100), and 2.1g of chain transfer agent diethyl carbonate (DEC, denamplalia chemical limited) were put into a high-pressure polymerization reactor having an effective volume of 10 liters, and stirred until the rotation speed was 450rpm, and the bottom liquid was uniformly mixed. Under the vacuum condition, nitrogen is introduced for a plurality of times for removing oxygen (the oxygen content is less than 20ppm), and then 2.5g of tert-amyl peroxypivalate (TAPP, Zibo Zhenghua auxiliary agent Co., Ltd.) as an initiator, 2510g of vinylidene fluoride, 120g of hexafluoropropylene and 2.4g of vinyltriethoxysilane (Ailquest A-151, a U.S. Megaku) are added. The temperature was raised to 45 ℃ to start the polymerization. In the reaction process, the temperature is reduced by circulating water, after the reaction temperature is stable, 1120g of 2% vinyl triethoxysilane (Ailquest A-151, May, USA) aqueous solution is continuously added, the reaction pressure is maintained at 8.4Mpa, 240g of aqueous dispersion containing 2.5% tert-amyl peroxypivalate and 3.0% diethyl carbonate is continuously supplemented, and the stirring speed is gradually adjusted according to the liquid level change in the polymerization kettle. After the reaction raw materials are added, the reaction temperature is kept at 45 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

[ example 8 ]

At room temperature, 4580g of deionized water, 3.6g of polyvinyl alcohol PVA17-88 (Beijing Yinuoka Tech Co., Ltd.), 1.5g of hydroxypropyl methylcellulose (HPMC, Shandong Hechada chemical product brand number HEADPEL 75HD100), and 3.0g of chain transfer agent diethyl carbonate (DEC, Jinan Lailai chemical Co., Ltd.) were put into a high-pressure polymerization reactor having an effective volume of 10 liters, stirred at a rotation speed of 600rpm, and the bottom liquid was mixed uniformly. Under the vacuum condition, nitrogen is introduced for a plurality of times for replacing and removing oxygen (the oxygen content is less than 20ppm), and then 2.5g of tert-amyl peroxypivalate (TAPP, Zibo Zhenghua auxiliary agent Co., Ltd.), 2620g of vinylidene fluoride, 84g of perfluoroethyl vinyl ether (PEVE) and 2.0g of vinyl-tris (2-methoxyethoxy) silane (Ailquest A-172 in a Mediakupffer). The temperature was raised to 45 ℃ to start the polymerization. Cooling by circulating water in the reaction process, continuously adding 1350g of 1% vinyl triethoxysilane (Ailquest A-151 in America) aqueous solution after the reaction temperature is stable, maintaining the reaction pressure at 9.0Mpa, continuously supplementing 220g of aqueous dispersion containing 2.5% tert-amyl peroxypivalate and 3.0% diethyl carbonate, and gradually adjusting the stirring speed according to the liquid level change in the polymerization kettle. After the reaction raw materials are added, the reaction temperature is kept at 45 ℃, and when the reaction pressure is reduced to 3.0Mpa, the polymerization reaction is finished. The resulting polymer dispersion was degassed, washed with water, filtered, and dried at 90 ℃ for 10 hours to obtain a fluoropolymer resin.

Comparative example 1

Fluoropolymer resin was prepared in substantially the same manner as in example 1, except that: no vinyltrimethoxysilane is added in the whole process.

Comparative example 2

Fluoropolymer resin was prepared in substantially the same manner as in example 6, except that: the whole process does not add any methacryloxypropyltrimethoxysilane.

[ COMPARATIVE EXAMPLE 3 ]

At room temperature, 5000g of trifluorotrichloroethane solvent is added into a high-pressure polymerization kettle with the effective volume of 10 liters, stirring is started, nitrogen is introduced for a plurality of times to displace and remove oxygen under the vacuum condition, 3.6g of tert-amyl peroxypivalate as initiator (TAPP, Zibozhenhua auxiliary agent Co., Ltd.), 1600g of vinylidene fluoride and 12.8g of vinyltrimethoxysilane (Ailquest A-171, Ma-Tu-U.S.A.). Then heating to 50 ℃, starting polymerization reaction, then starting circulating water to reduce the temperature, controlling the temperature between 50 ℃ and 70 ℃ in the polymerization process, and controlling the maximum polymerization pressure to be 6.0 Mpa. When the polymerization pressure is less than 1.5MPa, the reaction temperature is lowered and the polymerization is terminated. And then drying the obtained polymerization product at high temperature, and removing the organic solvent to obtain the fluorine-containing polymer resin.

The fluoropolymer resins obtained in the examples and comparative examples were used to prepare electrodes for non-aqueous electrolyte secondary batteries, respectively, according to the methods described above, and to test the adhesive strength between the electrode binder composition and the metal current collector (aluminum foil), and to prepare lithium ion batteries and to perform battery cycle performance tests, the test results are shown in table 1:

TABLE 1 results of Performance test

The test results show that the performances of the fluoropolymer prepared in the examples are obviously superior to those of a comparative example, and show that the invention can improve the bonding strength between the electrode adhesive composition for the nonaqueous electrolyte secondary battery and a metal current collector (aluminum foil) by carrying out copolymerization modification on the ethylenically unsaturated silane and the vinylidene fluoride through a suspension polymerization method and introducing siloxane groups into a fluoropolymer chain segment, thereby improving the electrochemical performance and the service life of the electrode for the nonaqueous electrolyte secondary battery.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for a person skilled in the art, several modifications and additions can be made without departing from the method of the present invention, and these modifications and additions should also be considered as the protection scope of the present invention.

Claims

1. The preparation process of the fluoropolymer for improving the adhesion is characterized in that the fluoropolymer is prepared by suspension polymerization of the following components in the presence of an initiator, a polymerization stabilizer and optionally other auxiliary agents;

a component a: vinylidene fluoride;

and (b) component b: fluorine-containing or non-fluorine-containing comonomers;

and (c) component: an ethylenically unsaturated silane;

wherein, the component b is used in an amount of 0 to 10wt%, preferably 0 to 5wt% of the addition amount of the component a; the component c is used in an amount of 0.01 to 5wt%, preferably 0.1 to 3 wt%, based on the amount of component a added.

2. The process for preparing an adhesion-promoting fluoropolymer according to claim 1, wherein in component b, the fluorine-containing comonomer is selected from one or more of vinyl fluoride, trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene, 2,3,3, 3-tetrafluoropropene, hexafluoropropylene, hexafluoroisobutylene, perfluorobutylethylene, pentafluoropropene, 3,3, 3-trifluoro-1-propene, 2-trifluoromethyl-3, 3, 3-trifluoropropene, fluorinated vinyl ether; preferably, the fluorinated vinyl ether is one or more of perfluoromethyl vinyl ether, perfluoroethyl vinyl ether, perfluoropropyl vinyl ether and perfluorobutyl vinyl ether;

in the component b, the non-fluorine-containing comonomer is an ethylenic unsaturated monomer, preferably one or more of olefinic acid, olefinic ester, unsaturated nitrile and vinyl aromatic compound, more preferably one or more of acrylic acid, methacrylic acid, itaconic acid, maleic acid, methyl acrylate, methyl methacrylate, ethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl benzoate, vinylene carbonate, dimethyl maleate, diethyl maleate, di-n-propyl maleate, diisopropyl maleate, di-2-methoxyethyl maleate, dimethyl fumarate, diethyl fumarate, di-n-propyl fumarate, diisopropyl fumarate, acrylonitrile, styrene, vinyl toluene, alpha-methyl styrene.

3. The process for preparing an adhesion-promoting fluoropolymer according to claim 2, wherein the ethylenically unsaturated silane in component c contains at least one vinyl, allyl or acryloxy group attached to the silicon atom, and at least one Si-O bond;

preferably, the ethylenically unsaturated silane is selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltris (2-methoxyethoxy) silane, vinyltriisopropenoxysilane, vinylmethyldiacetoxysilane, vinyltriacetoxysilane, allyltrimethoxysilane, one or more of allylmethyldimethoxysilane, allyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, methacryloxypropylmethyldimethoxysilane, preferably at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris (2-methoxyethoxy) silane, methacryloxypropyltrimethoxysilane.

4. The process for preparing an adhesion-promoting fluoropolymer according to any of claims 1 to 3, wherein the polymeric stabilizer is selected from one or more of celluloses, polyvinyl alcohols, polyethylene glycols, polyacrylic acids, preferably one or more of methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose;

5. The process for preparing an adhesion-promoting fluoropolymer according to claim 4, wherein the initiator is an organic peroxide initiator, preferably diisopropyl peroxydicarbonate, diethyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di-2-ethylhexyl peroxydicarbonate, 2' -azobis (2, 4-dimethylvaleronitrile), 2' -azobis (4-methoxy-2, 4-dimethylvaleronitrile), tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, tert-amyl peroxypivalate, dibenzoyl peroxide, tert-butyl peroxy2-ethylhexanoate, tert-butyl peroxymaleate, dicumyl peroxide, tert-butyl peroxycumyl peroxyacetate, 2' -di (tert-butylperoxy) butane, di (tert-butylperoxy) n-butyl peroxyl, di (tert-butyl peroxyl) n-butyl peroxyl, di (2, di-butyl-n-butyl peroxyl) butane, di (tert-butyl peroxyl) n-butyl peroxyl, di (2, di (tert-butyl peroxyl) n-butyl peroxyl, di (tert-butyl) n-butyl peroxyl, di (2, di (tert-butyl) n-butyl) peroxyl) n-butyl) n-butyl peroxyl, o-butyl) peroxyl, o-butyl peroxyl, o-butyl, 2, o-butyl, One or more of tert-butyl cumyl peroxide and tert-butyl isopropyl carbonate;

6. The process of claim 5 wherein the other auxiliary agents include optionally pH adjusting agents, chain transfer agents.

7. The process of any of claims 1-3 wherein the polymerization temperature is 40-100 ℃ and the pressure is 3.0-15.0MPa gauge.

8. An adhesion promoting fluoropolymer made by the process of any of claims 1-7.

9. Use of the adhesion-improving fluoropolymer obtained by the process according to any one of claims 1 to 7 in an electrode binder for a non-aqueous electrolyte secondary battery.