CN112409527B - Vinylidene fluoride copolymer containing metal ions and preparation method thereof - Google Patents
Vinylidene fluoride copolymer containing metal ions and preparation method thereof Download PDFInfo
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- CN112409527B CN112409527B CN202011315830.5A CN202011315830A CN112409527B CN 112409527 B CN112409527 B CN 112409527B CN 202011315830 A CN202011315830 A CN 202011315830A CN 112409527 B CN112409527 B CN 112409527B
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F214/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen
- C08F214/18—Monomers containing fluorine
- C08F214/22—Vinylidene fluoride
- C08F214/225—Vinylidene fluoride with non-fluorinated comonomers
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/04—Acids; Metal salts or ammonium salts thereof
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- C08F220/00—Copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride ester, amide, imide or nitrile thereof
- C08F220/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
- C08F220/52—Amides or imides
- C08F220/54—Amides, e.g. N,N-dimethylacrylamide or N-isopropylacrylamide
- C08F220/56—Acrylamide; Methacrylamide
Abstract
The vinylidene fluoride copolymer containing the metal ions comprises a polyvinylidene fluoride structural unit, an acrylamide structural unit and a vinyl lithium carbonate structural unit; the preparation method comprises the following steps: and respectively adding a vinylidene fluoride monomer, an acrylamide monomer, a vinyl lithium carbonate monomer and an initiator into a reaction device, and carrying out one-step copolymerization by using a polymerization reaction method to obtain the high-performance ethylene-propylene-diene monomer. The invention reserves the advantageous structure of polyvinylidene fluoride, ensures that the copolymer has enough mechanical strength and thermal stability, overcomes the defects of the existing PVDF as the polymer lithium ion battery material by introducing a lithium ion high-efficiency transmission structural unit, a polar group and a large number of ultrastable structural units, optimizes the transmission efficiency of lithium ions, improves the ionic conductivity of the lithium battery, reduces the polarization of the battery in the charging process, improves the charge and discharge performance of the battery, and provides a new material and a new method for further development and application of the lithium battery.
Description
Technical Field
The invention relates to a lithium ion polymer and a preparation method thereof, in particular to a vinylidene fluoride copolymer containing metal ions and a preparation method thereof, belonging to the technical field of production and manufacture of lithium ion polymer batteries.
Background
The polymer lithium ion battery has the characteristics of small volume, light weight, high energy density, small self-discharge, no memory effect, good safety performance, capability of being made into any shape and the like, becomes the most advanced rechargeable battery at present, and is researched and developed vigorously by major scientific and technological strong countries in the world at present.
Lithium polymer batteries are mainly composed of a positive electrode, a negative electrode, separator paper, and the like, and in lithium polymer batteries developed at present, polymer materials are mainly applied to the positive electrode and an electrolyte.
The high-molecular material polyvinylidene fluoride (PVDF) is a homopolymer of VDF, and is a thermoplastic fluorine-containing polymer, and the repeating unit of the molecular chain of the polymer is-CH2-CF2The PVDF fluororesin has the characteristics of both fluorine-containing resin and general resin due to the special molecular structure, has good chemical stability and thermal stability, and has excellent electrochemical performance which is widely applied to lithium batteries as a positive electrode material, a binder, a negative electrode material, a battery diaphragm and the like.
Since the operation process of the lithium battery can be regarded as the "reciprocating motion" of lithium ions between two electrodes, along with the cyclic intercalation and deintercalation of the lithium ions, the polymer used in the lithium battery has higher requirements on the conductivity, lithium ion mobility and electrochemical stability of the material.
However, because polyvinylidene fluoride is a crystalline polymer, the crystallinity is between 60% and 80%, the dielectric constant and the ohmic resistance are high, and the crystal melting temperature is about 140 ℃, under the normal use temperature of the battery, the PVDF polymer is purely used as a battery material, and the crystalline unit of the PVDF polymer can obstruct the transmission of ions in the electrolytic liquid, thereby greatly reducing the transmission efficiency of the ions and seriously influencing the charge and discharge performance of the lithium battery.
In addition, the stronger acting force among the PVDF molecules enables the internal free volume of the polymer to be smaller, so that the number of internal ion transfer channels is reduced;
more seriously, the smaller internal free volume of PVDF polymer can reduce the adsorption capacity of the electrolyte and reduce the "back-and-forth" mobility of lithium ions.
At present, aiming at the defects of PVDF in lithium batteries, the prior art mainly introduces a conductive agent containing a lithium sulfonate component in a blending mode to improve the ion transmission performance of materials, such as:
the invention patent application (application number: 201611173765.0) provides a single ion gel polymer electrolyte and a preparation method thereof;
the invention patent application (application number: 201611145093.2) provides a lithium single-ion conductive solid polymer electrolyte, and the like.
However, although the addition of the conductive agent is effective in improving the electrochemical performance of the material, it reduces the compatibility of PVDF with other materials, weakens the adhesive force of the polymer material itself and the durability of the adhesive force, and causes problems such as easy partial or complete peeling of the electrode binder layer from the current collector, deterioration of load characteristics, and capacity deterioration.
In addition, there is also a related art that introduces a lithium sulfonate structure into a PVDF structure by way of copolymerization to improve ion conductivity, such as:
the invention relates to a process for manufacturing an electrolyte membrane special for a solid lithium ion battery, which is provided by the patent application (application number: 02138204.2).
However, the copolymer obtained in this way has lower chemical stability and other properties than those of the corresponding PVDF homopolymer because of the introduction of a large number of carbon-hydrogen bonds (C-H) in the copolymerization process and the stability of the copolymer is not as high as that of the carbon-fluorine bonds (C-F) in the PVDF structure.
Therefore, the chemical structure of the PVDF homopolymer is optimized to obtain the vinylidene fluoride multipolymer with more excellent performance, the lithium ion mobility of the PVDF copolymer is effectively improved, and the method has important significance for the development and application of the lithium ion battery.
Disclosure of Invention
In order to overcome the defects of the related technology, the invention provides a vinylidene fluoride copolymer containing metal ions and a preparation method thereof, aiming at:
the structural advantage of PVDF is retained, and meanwhile, a structural unit with high ion transmission efficiency (lithium carbonate structural unit) is introduced into the structure in a copolymerization mode, so that a high-speed lithium ion transmission channel can be constructed in the material, the purposes of optimizing the transmission efficiency of PVDF ions and improving the ionic conductivity of the lithium battery are finally realized, and the polarization of the battery in the charging process can be reduced, so that the charging and discharging performance of the battery is improved, and an important polymer material is provided for the further research and application of the lithium battery;
in addition, acrylamide units in the copolymer structure can improve the hydrophilicity of the PVDF polymer, and effectively increase the adsorption capacity of the electrolyte and the migration rate of lithium ions;
in addition, a large amount of polar groups (ester bonds and carbonic acid bonds) are introduced into the copolymer, so that the physical and chemical properties (viscosity, solubility, crystallinity and the like) of the copolymer can be effectively regulated and controlled by regulating the proportion of the polar units.
In order to achieve the above object, the present invention provides a vinylidene fluoride copolymer containing metal ions, the copolymer comprising:
the copolymer consists of three compound structural units, namely a polyvinylidene fluoride structural unit (A) consisting of x molar parts of vinylidene fluoride monomers, a acrylamide structural unit (B) consisting of y molar parts of acrylamide monomers and a vinyl lithium carbonate structural unit (C) consisting of z molar parts of vinyl lithium carbonate monomers; and is
The copolymer has the following structural general formula:
among the acrylamide units, it:
r is-H, -CH3、-CH(CH3)2、-CH2CH3、-(CH2)3-OCH3、-CH2-OH、-(CH2)11-CH3、-(CH2)3-N(CH3)2、-C(CH3)3、-CH(CH3)2、-CH2C6H5、-C6H5Any one of the above;
among the vinyl lithium carbonate structural units, it:
n is an integer or a half number of 0 or more;
the respective mole fractions of the polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit are respectively as follows:
x/(x+y+z)＝0.50～0.80，y/(x+y+z)＝0.10～0.40，z/(x+y+z)＝0.10～0.40。
further, the method comprises the following steps:
in the acrylamide structural unit, the following:
r is-H, - (CH)2)3-N(CH3)2、-CH3、-CH(CH3)2Any one of the above;
among the vinyl lithium carbonate structural units, it:
n is any one of 1, 2 and 3;
the respective mole fractions of the polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit are respectively as follows:
x/(x+y+z)＝0.60～0.80，y/(x+y+z)＝0.10～0.30，z/(x+y+z)＝0.10～0.30。
further, the invention also provides a preparation method of the vinylidene fluoride copolymer containing the metal ions, which comprises the following steps:
in a reaction device, adding a vinylidene fluoride monomer, a acrylamide monomer, a vinyl lithium carbonate monomer and an initiator according to respective mole fractions of a polyvinylidene fluoride structural unit, a acrylamide structural unit and a vinyl lithium carbonate structural unit, and copolymerizing by adopting a polymerization reaction method to prepare the vinylidene fluoride copolymer containing the metal ions, wherein the reaction formula is as follows:
further, in the above preparation method:
the reaction device is a high-pressure reaction kettle;
in the step of respectively adding the vinylidene fluoride monomer, the acrylamide monomer, the vinyl lithium carbonate monomer and the initiator, the method specifically comprises the following steps:
firstly, adding a acrylamide monomer, a vinyl lithium carbonate monomer and an initiator into the high-pressure reaction kettle, repeatedly evacuating to remove oxygen, then filling a vinylidene fluoride monomer gas in a nitrogen atmosphere, and keeping the pressure in the high-pressure reaction kettle between 1.25 and 1.85 MPa;
the step of preparing the vinylidene fluoride copolymer containing the metal ions by copolymerization through a polymerization reaction method specifically comprises the following steps:
slowly heating the materials in the high-pressure reaction kettle to 75-135 ℃, reacting for 12-36 hours by a polymerization reaction method under mechanical stirring, cooling to room temperature, releasing unreacted gas to obtain a vinylidene fluoride copolymer emulsion containing metal ions, demulsifying the emulsion by using an ethanol solution to obtain a broken emulsion, washing the broken emulsion to remove an emulsifier and unreacted vinylidene fluoride monomer, acrylamide monomer and vinyl lithium carbonate monomer, and drying to obtain the vinylidene fluoride copolymer containing metal ions.
Further:
the initiator is one of benzoyl peroxide, azo compounds or persulfate;
the polymerization reaction method is any one of emulsion polymerization, suspension polymerization or aqueous solution polymerization.
And further:
the emulsion polymerization method further comprises an emulsifier, wherein the emulsifier is ammonium perfluorooctanoate.
And further:
the aqueous phase solution polymerization method further comprises a dispersion medium, wherein the dispersion medium is trifluorotrichloroethane.
Further, the method comprises the following steps:
and after the emulsion is demulsified by an ethanol solution to obtain a demulsified emulsion, dissolving the demulsified solution in an organic solvent to wait for the subsequent washing and drying operation steps, wherein the organic solvent is one or a mixture of more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, ethanol, isopropanol, dimethyl sulfoxide or ethyl acetate.
Compared with the prior art, the invention has the beneficial effects and remarkable progresses that:
1) the vinylidene fluoride copolymer containing the metal ions, provided by the invention, adopts a copolymerization mode to introduce a vinyl lithium carbonate conduction unit into a PVDF structure, so that a new method is provided for applying a PVDF material to the field of lithium batteries;
2) according to the vinylidene fluoride copolymer containing the metal ions, a functional high-efficiency lithium ion transmission structure unit is introduced into the copolymer through vinyl lithium carbonate;
3) the vinylidene fluoride copolymer containing the metal ions provided by the invention contains a lithium carbonate structure, and the vinylidene fluoride-acrylamide-vinyl lithium carbonate copolymer is prepared by one-step copolymerization without a subsequent alkali treatment process, so that the chemical degradation of the PVDF structure is avoided;
4) the monomer vinyl lithium carbonate in the vinylidene fluoride copolymer containing the metal ions has a self-emulsifying function, and an emulsifier is avoided in the emulsion polymerization process;
5) the acrylamide unit in the vinylidene fluoride copolymer containing the metal ions can improve the hydrophilicity of the PVDF copolymer, and effectively increase the adsorption capacity of electrolyte and the migration rate of lithium ions;
6) the vinylidene fluoride copolymer containing the metal ions provided by the invention retains the structural advantages of PVDF, and simultaneously introduces a large number of polar groups (ester bonds and carbonate bonds), so that the physicochemical properties of the copolymer, such as the viscosity, the solubility, the crystallinity and the like of the copolymer, can be effectively regulated and controlled;
7) the lithium carbonate structural unit in the vinylidene fluoride copolymer containing the metal ions is connected with the controllable chain segment, so that the crystallinity and the ionic conductivity of the copolymer can be effectively controlled.
Detailed Description
In order to make the objects, technical solutions, advantages and significant progress of the present invention clearer, the following will clearly and completely describe embodiments and examples provided by the present invention, and obviously, all the described embodiments and examples are only part of the embodiments and examples of the present invention, but not all of them;
all other embodiments or examples, which can be derived by a person skilled in the art from the embodiments presented herein without making any inventive step, are within the scope of the claimed invention.
It should be noted that:
the terms "first," "second," "again," and the like in the description and in the claims of the present invention are used for distinguishing between different objects and not for describing a particular order;
moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements but may alternatively include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus;
in addition, in the description and claims of the present invention:
the copolymer consists of three compound structural units, namely a polyvinylidene fluoride structural unit (A) consisting of x molar parts of vinylidene fluoride monomers, a acrylamide structural unit (B) consisting of y molar parts of acrylamide monomers and a vinyl lithium carbonate structural unit (C) consisting of z molar parts of vinyl lithium carbonate monomers; and is
The copolymer has the following structural general formula:
further, in the above structural general formula:
x, y and z are respectively the respective mole fractions of a polyvinylidene fluoride structural unit, a acrylamide structural unit and a vinyl lithium carbonate structural unit; and is provided with
The polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit respectively account for the following molar parts in the structure of the vinylidene fluoride copolymer containing metal ions:
x/(x + y + z), y/(x + y + z), and z/(x + y + z).
It should also be noted that:
the following specific embodiments and examples may be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments and examples; and is
The reaction apparatus, monomer compounds, initiators, emulsifiers, demulsifiers, organic solvents, and the like, referred to in the following examples and illustrations, are commercially available.
The technical solution of the present invention will be described in detail below with specific examples and examples.
Example one
This example provides a vinylidene fluoride copolymer containing metal ions.
The vinylidene fluoride copolymer containing metal ions provided in this embodiment includes:
the copolymer consists of three compound structural units, namely a polyvinylidene fluoride structural unit (A) consisting of x molar parts of vinylidene fluoride monomers, a acrylamide structural unit (B) consisting of y molar parts of acrylamide monomers and a vinyl lithium carbonate structural unit (C) consisting of z molar parts of vinyl lithium carbonate monomers; and is
The copolymer has the following structural general formula:
wherein:
among the acrylamide units, it:
r is-H, -CH3、-CH(CH3)2、-CH2CH3、-(CH2)3-OCH3、-CH2-OH、-(CH2)11-CH3、-(CH2)3-N(CH3)2、-C(CH3)3、-CH(CH3)2、-CH2C6H5、-C6H5Any one of the above;
among the vinyl lithium carbonate structural units, it:
n is an integer or a half number of 0 or more;
the respective mole fractions of the polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit are respectively as follows:
x/(x+y+z)＝0.50～0.80，y/(x+y+z)＝0.10～0.40，z/(x+y+z)＝0.10～0.40。
as a preferred technical solution, further:
in the acrylamide structural unit, the following components:
r is-H, - (CH)2)3-N(CH3)2、-CH3、-CH(CH3)2Any one of the above;
among the vinyl lithium carbonate structural units, it:
n is any one of 1, 2 and 3;
the respective mole fractions of the polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit are respectively as follows:
x/(x+y+z)＝0.60～0.80，y/(x+y+z)＝0.10～0.30，z/(x+y+z)＝0.10～0.30。
from the above description and the general structural formulae, it can be found that:
firstly, the vinylidene fluoride copolymer containing metal ions provided by this embodiment retains the structural advantages of PVDF, and introduces a structural unit (lithium carbonate structural unit) with high ion transmission efficiency into the structure by copolymerization, so as to construct a high-speed lithium ion transmission channel in the material, and finally achieve the purposes of optimizing the transmission efficiency of PVDF ions and improving the ionic conductivity of lithium batteries, and reduce the polarization of the batteries during charging, thereby improving the charge and discharge performance of the batteries, and providing an important polymer material for further research and application of the lithium batteries;
in addition, acrylamide units in the copolymer structure can improve the hydrophilicity of the PVDF polymer, and effectively increase the adsorption capacity of the electrolyte and the migration rate of lithium ions;
in addition, a large amount of polar groups (ester bonds and carbonic acid bonds) are introduced into the copolymer, so that the physical and chemical properties (viscosity, solubility, crystallinity and the like) of the copolymer can be effectively regulated and controlled by regulating the proportion of the polar units.
Example two
This example provides a method for preparing a vinylidene fluoride copolymer containing metal ions.
The preparation method of the vinylidene fluoride copolymer containing the metal ions provided by the embodiment comprises the following steps:
in a reaction device, adding a vinylidene fluoride monomer, a acrylamide monomer, a vinyl lithium carbonate monomer and an initiator according to respective mole fractions of a polyvinylidene fluoride structural unit, a acrylamide structural unit and a vinyl lithium carbonate structural unit, and copolymerizing by adopting a polymerization reaction method to prepare the vinylidene fluoride copolymer containing the metal ions, wherein the reaction formula is as follows:
further, in the above preparation method:
the reaction device is a high-pressure reaction kettle;
in the step of respectively adding the vinylidene fluoride monomer, the acrylamide monomer, the vinyl lithium carbonate monomer and the initiator, the method specifically comprises the following steps:
firstly, adding a acrylamide monomer, a vinyl lithium carbonate monomer and an initiator into the high-pressure reaction kettle, repeatedly evacuating to remove oxygen, then filling a vinylidene fluoride monomer gas in a nitrogen atmosphere, and keeping the pressure in the high-pressure reaction kettle between 1.25 and 1.85 MPa;
the step of preparing the vinylidene fluoride copolymer containing the metal ions by copolymerization through a polymerization reaction method specifically comprises the following steps:
slowly heating the materials in the high-pressure reaction kettle to 75-135 ℃, reacting for 12-36 hours by a polymerization reaction method under mechanical stirring, cooling to room temperature, releasing unreacted gas to obtain a vinylidene fluoride copolymer emulsion containing metal ions, demulsifying the emulsion by using an ethanol solution to obtain a broken emulsion, washing the broken emulsion to remove an emulsifier and unreacted vinylidene fluoride monomer, acrylamide monomer and vinyl lithium carbonate monomer, and drying to obtain the vinylidene fluoride copolymer containing metal ions.
In this embodiment:
the initiator can be one of benzoyl peroxide, azo compounds or persulfate;
the polymerization method may be any of emulsion polymerization, suspension polymerization, or aqueous solution polymerization.
During the preparation process by using the emulsion polymerization method, an emulsifier can be further included, and the emulsifier is ammonium perfluorooctanoate.
In the preparation process by using the aqueous phase solution polymerization method, the aqueous phase solution polymerization method also comprises a dispersion medium, and the dispersion medium can be trifluorotrichloroethane.
In addition, after the emulsion is demulsified by the ethanol solution to obtain a demulsified emulsion, the demulsified solution can be dissolved in an organic solvent to wait for the subsequent washing and drying operation steps;
the organic solvent may be one or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, ethanol, isopropanol, dimethylsulfoxide, or ethyl acetate.
From the above description, it can be found that:
first, in the preparation method of the vinylidene fluoride copolymer containing the metal ions provided in this embodiment, a polymerization reaction method is adopted to copolymerize three monomers including vinylidene fluoride, acrylamide, and vinyl lithium carbonate into a whole in one step, and a subsequent alkali treatment process is not required, so that an advantageous skeleton structure (-CH) in the copolymer is avoided2CF2-) chemical degradation;
in addition, the vinyl lithium carbonate in the comonomer has a self-emulsifying function, so that an emulsifier is not needed or used little in the polymerization process, the production can be ensured, the production cost can be reduced, and the waste discharge can be reduced, thereby having great popularization and application values.
In addition, the preparation method of the vinylidene fluoride copolymer containing metal ions provided by this embodiment may:
controlling the molecular weight, free volume, molecular weight distribution and crystallinity of the copolymer by adjusting the feeding molar ratio of the three monomers;
the crystallinity and the ionic conductivity of the copolymer are further regulated and controlled by regulating the length of an alkyl linking group in the vinyl lithium carbonate;
by selecting different types of acrylamide monomers, the hydrophilicity of the PVDF copolymer is further regulated and controlled, and the adsorption capacity of the electrolyte and the migration rate of lithium ions are effectively increased.
According to the above description, it can be seen that the vinylidene fluoride copolymer containing metal ions and the preparation method thereof provided by the invention have at least the following advantages:
1) according to the vinylidene fluoride copolymer containing the metal ions and the preparation method thereof, a vinyl lithium carbonate conducting unit is introduced into a PVDF structure in a copolymerization mode, so that a new method is provided for applying a PVDF material to the field of lithium batteries;
2) according to the vinylidene fluoride copolymer containing the metal ions and the preparation method thereof, the vinylidene fluoride-acrylamide-vinyl lithium carbonate copolymer is prepared by one-step copolymerization, a subsequent alkali treatment process is not needed, and chemical degradation of a PVDF structure is avoided;
3) in the vinylidene fluoride copolymer containing the metal ions and the preparation method thereof provided by the invention, the vinyl lithium carbonate as a comonomer has a self-emulsifying function, and the use of an emulsifier is avoided in the emulsion polymerization process;
4) in the vinylidene fluoride copolymer containing the metal ions and the preparation method thereof provided by the invention, the acrylamide unit can improve the hydrophilicity of the PVDF copolymer, and effectively increase the adsorption capacity of electrolyte and the migration rate of lithium ions;
5) in the vinylidene fluoride copolymer containing metal ions and the preparation method thereof provided by the invention, a large number of polar groups (ester bonds and carbonic acid bonds) are introduced, so that the physicochemical properties of the copolymer, such as the viscosity, the solubility, the crystallinity and the like of the copolymer, can be effectively regulated and controlled;
6) in the vinylidene fluoride copolymer containing the metal ions and the preparation method thereof provided by the invention, the lithium carbonate structural unit in the copolymer is connected with the controllable chain segment, so that the crystallinity and the ionic conductivity of the copolymer can be effectively controlled.
In summary, it can be seen that:
the vinylidene fluoride copolymer containing the metal ions and the preparation method thereof provided by the invention are extremely novel and creative and have extremely high popularization and application values.
To further assist understanding of the technical solutions of the present invention, the technical solutions of the present invention are described in more detail below by providing several specific implementation examples.
Examples 1A,
Adding CH with the structural formula into a high-pressure reaction kettle which can endure 10MPa2＝CHCONH2Acrylamide monomer and structural formula of2＝CH-C2H4-COOLi+Repeatedly evacuating to remove oxygen, then filling into a mixture with a structural formula of CH in a nitrogen atmosphere2＝CF2Vinylidene fluoride gas of (a);
wherein:
is represented by the structural formula CH2＝CF2The polyvinylidene fluoride structural unit formed by the vinylidene fluoride gas has a structural formula of CH2＝CHCONH2Acrylamide structural unit composed of acrylamide monomer, and a monomer having a structural formula of CH2＝CH-C2H4-COOLi+The mol fraction ratio of the vinyl lithium carbonate structural unit formed by the vinyl lithium carbonate monomer is as follows:
vinylidene fluoride structural unit, acrylamide structural unit and vinyl lithium carbonate structural unit are 0.55: 0.35: 0.10;
keeping the pressure of the reaction kettle between 1.25MPa, slowly heating to 100 ℃, adding ammonium perfluorooctanoate as an emulsifier under mechanical stirring, and carrying out polymerization reaction for 24 hours by adopting an emulsion polymerization method;
after the reaction is finished, cooling the feed liquid to room temperature, releasing unreacted gas to obtain uniform copolymer emulsion, demulsifying the emulsion by using an ethanol solution, washing, removing an emulsifier, unreacted vinylidene fluoride monomer, acrylamide monomer and vinyl lithium carbonate monomer, and drying to obtain a target product.
Examples 2,
The operation process and method of the present example are substantially the same as those of example 1, except that:
the added acrylamide monomer has a structural formula: CH (CH)2＝CHCONH2(ii) a The structural formula of the added vinyl lithium carbonate monomer is as follows: CH (CH)2＝CH-C2H4-COOLi+；
Further:
is represented by the structural formula CH2＝CF2The polyvinylidene fluoride structural unit formed by the vinylidene fluoride gas has a structural formula of CH2＝CHCONH2Acrylamide structural unit composed of acrylamide monomer, and a monomer having a structural formula of CH2＝CH-C2H4-COOLi+The mol fraction ratio of the vinyl lithium carbonate structural unit formed by the vinyl lithium carbonate monomer is as follows:
vinylidene fluoride structural unit, acrylamide structural unit and vinyl lithium carbonate structural unit are 0.70: 0.20: 0.10;
the pressure of the reaction kettle is kept at 1.50MPa, and the materials are slowly heated and kept at about 95 ℃;
in addition, the polymerization reaction still adopts emulsion polymerization method without adding emulsifier, and vinyl lithium carbonate structural unit itself is taken as emulsifier to carry out polymerization reaction.
Examples 3,
The operation process and method of the present example are substantially the same as those of example 1, except that:
the initiator adopts azo compound;
the added acrylamide monomer has a structural formula: CH (CH)2＝CHCONH2；
The structural formula of the added vinyl lithium carbonate monomer is as follows: CH (CH)2＝CH-(C2H4)2-COOLi+；
Further:
is represented by the structural formula CH2＝CF2The polyvinylidene fluoride structural unit formed by the vinylidene fluoride gas has a structural formula of CH2＝CHCONH2Acrylamide structural unit composed of acrylamide monomer, and a monomer having a structural formula of CH2＝CH-(C2H4)2-COOLi+The mol fraction ratio of the vinyl lithium carbonate structural unit formed by the vinyl lithium carbonate monomer is as follows:
vinylidene fluoride structural unit, acrylamide structural unit and vinyl lithium carbonate structural unit are 0.60: 0.10: 0.30;
the pressure of the reaction kettle is kept at 1.85MPa, and the materials are slowly heated and kept at about 75 ℃;
in addition, the polymerization reaction adopts a suspension polymerization method and does not add an emulsifier.
Examples 4,
The operation process and method of the present example are substantially the same as those of example 3, except that:
the added acrylamide monomer has a structural formula: CH (CH)2＝CHCONH2；
The structural formula of the added vinyl lithium carbonate monomer is as follows: CH (CH)2＝CH-C5H10-COOLi+；
Further:
is represented by the structural formula CH2＝CF2The polyvinylidene fluoride structural unit formed by the vinylidene fluoride gas has a structural formula of CH2＝CHCONH2Acrylamide structural unit composed of acrylamide monomer, and a monomer having a structural formula of CH2＝CH-C5H10-COOLi+The mol fraction ratio of the vinyl lithium carbonate structural unit formed by the vinyl lithium carbonate monomer is as follows:
vinylidene fluoride structural unit, acrylamide structural unit and vinyl lithium carbonate structural unit are 0.80: 0.10;
the pressure of the reaction kettle is kept at 1.60MPa, and the materials are slowly heated and kept at about 135 ℃.
Examples 5,
The operation process and method of the present example are substantially the same as those of example 1, except that:
the initiator adopts sulfate;
the added acrylamide monomer has a structural formula: CH (CH)2＝CHCONHCH3；
The structural formula of the added vinyl lithium carbonate monomer is as follows: CH (CH)2＝CH-(C2H4)3-COOLi+；
Further:
is represented by the structural formula CH2＝CF2The polyvinylidene fluoride structural unit formed by the vinylidene fluoride gas has a structural formula of CH2＝CHCONHCH3Acrylamide structural unit composed of acrylamide monomer, and a monomer having a structural formula of CH2＝CH-(C2H4)3-COOLi+The mol fraction ratio of the vinyl lithium carbonate structural unit formed by the vinyl lithium carbonate monomer is as follows:
vinylidene fluoride structural unit, acrylamide structural unit and vinyl lithium carbonate structural unit are 0.58: 0.28: 0.14;
the pressure of the reaction kettle is kept at 1.75MPa, and the materials are slowly heated and kept at about 85 ℃;
in addition, the polymerization reaction adopts an aqueous solution polymerization method, and the emulsifier is not added, but trifluorotrichloroethane is added as a dispersion medium to carry out polymerization reaction to obtain polyvinylidene fluoride, acrylamide and vinyl lithium carbonate copolymer emulsion;
and demulsifying the emulsion by using an ethanol solution, dissolving the emulsion in one or more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, ethanol, isopropanol, dimethyl sulfoxide or ethyl acetate for storage, washing when necessary, removing an emulsifier, an organic solvent and unreacted structural units, and drying to obtain the target product.
Examples 6,
The operation process and method of the present example are substantially the same as those of example 5, except thatIn the following steps: the structural formula of the added vinyl lithium carbonate monomer is as follows: CH (CH)2＝CH-C2H4-COOLi+；
Further:
is represented by the structural formula CH2＝CF2The polyvinylidene fluoride structural unit formed by the vinylidene fluoride gas has a structural formula of CH2＝CHCONHCH3And a structural unit of acrylamide formed by the acrylamide monomer of (a), and a structural formula of2＝CH-C2H4-COOLi+The mol fraction ratio of the vinyl lithium carbonate structural unit formed by the vinyl lithium carbonate monomer is as follows:
vinylidene fluoride structural units, acrylamide structural units and vinyl lithium carbonate structural units are 0.50: 0.10: 0.40, the pressure of a reaction kettle is kept at 1.55MPa, and the materials are slowly heated and maintained at about 105 ℃.
The following are specifically mentioned: the above cases are provided only to illustrate some embodiments of the present invention, and are for vinyl-alkyl carbonates
The lithium structural units have the general structural formula, in addition to the monomers of the specific structural formulae listed in the above cases:
CH2＝CH-(C2H4)n-COOLi+
the related products obtained after copolymerization of the monomers marked with n being an integer or half of 0 or more, especially n being an integer or half of 1-3, also have the same or similar functions and effects as the products obtained in the above cases, and the copolymerization method and control conditions thereof are also the same or similar to the methods and conditions listed in the above cases and are included in the ranges listed in the above examples, therefore, the related processes and control methods are not repeated and only summarized and described.
To further illustrate the embodiments of the present invention and the advantages achieved by the various cases, the following description will be made with reference to specific effect embodiments.
It should be noted that:
the detection instrument and the detection reagent according to the following effect examples are commercially available, and the detection method used is a conventional technique that can be searched.
Effect embodiment:
1) determination of the average molecular weight of the copolymer
The average molecular weight is obtained by measuring the weight average relative molecular weight of the copolymer by a PL-22 type high temperature gel permeation chromatograph.
In the detection process, N-dimethylformamide is taken as a solvent, the detection is carried out at 160 ℃, and data are processed by a universal correction method with narrow distribution vinylidene fluoride as a standard sample.
The average molecular weight values of the copolymers of cases 1 to 6 obtained by the test are shown in Table 1.
2) Determination of copolymer crystallinity
The crystallinity of the copolymer was measured by DSC2910 Differential Scanning Calorimeter (British name: Differential Scanning Calorimeter) manufactured by TA of America, and the copolymer was tested under nitrogen protection according to the method specified in GB/T19466.3-2004.
During detection, the sample is heated from room temperature to 150 ℃ at the speed of 10 ℃/min, is kept warm for 5min, is naturally cooled to room temperature, is subjected to temperature rise scanning at the speed of 10 ℃/min (from room temperature to 150 ℃), and is recorded with a corresponding DSC curve to obtain the corresponding melting enthalpy delta HfThen, the percent crystallinity of each copolymer was calculated according to the following formula:
Xi＝(ΔHf÷293)×100％
in the formula:
ΔHfis the enthalpy of fusion of the sample polymer in units of J.g-1；
293 is the enthalpy of fusion at 100% crystallinity of polyethylene, in J.g-1。
The percent crystallinity of each copolymer obtained in cases 1 to 6 was examined and is shown in Table 1.
3) Determination of the free volume of the copolymer:
the free volume of the copolymer is measured by soaking the copolymer in 80 ℃ propylene carbonate serving as an electrolyte of a lithium battery for 10 hours, measuring the volume of the copolymer before and after soaking, and determining the difference value of the volume before and after soaking as the free volume of the copolymer, namely:
Vf＝V－Vo
in the formula:
Vois the volume of the initial copolymer sample;
v is the volume of the copolymer sample after soaking.
The free volume of each copolymer of cases 1 to 6 obtained by the examination is shown in Table 1.
4) Determination of the ionic conductivity of the copolymer:
the determination of the ionic conductivity of the copolymer is to thermally press each copolymer into a film at 150 ℃, then test the film resistance R of the film after swelling propylene carbonate on the film by adopting a two-electrode method, the adopted detection instrument is an electrochemical workstation Autolab PGSTA302, the frequency interval is 106-10 Hz, and the conductivity is calculated by the following calculation formula:
σ＝L/RS
in the formula:
σ is the conductivity (s/cm) of the sample after swelling;
l is the thickness (cm) of the swollen membrane;
r is the resistance (omega) of the membrane after swelling;
s is the area (cm) of the test portion of the sample after swelling2)。
The ionic conductivity of the copolymers obtained in cases 1 to 6 was measured and is shown in Table 1.
TABLE 1
| Molecular weight | Crystallinity (%) | Ion conductivity (S/cm) | |
| Example 1 | 420000 | 38 | 3.9×10-4 |
| Example 2 | 430000 | 36 | 4.5×10-4 |
| Example 3 | 460000 | 32 | 2.9×10-3 |
| Example 4 | 440000 | 30 | 2.1×10-3 |
| Example 5 | 435000 | 34 | 0.6×10-4 |
| Example 6 | 450000 | 33 | 0.2×10-4 |
The test results are as follows: molecules of examples 1-6The amount is 420000-460000, the crystallinity is 30-38%, and the ionic conductivity is 0.2X 10-4-2.9×10-3. The results prove that the polymeric material provided by the invention has better stability, crystallinity and ionic conductivity.
In the course of the description of the above description:
the description of the terms "present embodiment," "present example," "further," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention;
in this specification, the schematic representations of the terms used above are not necessarily for the same embodiment or example, and the particular features, structures, materials, or characteristics described, etc., may be combined or brought together in any suitable manner in any one or more embodiments or examples;
furthermore, those of ordinary skill in the art may combine or combine features of different embodiments or examples and features of different embodiments or examples described in this specification without undue conflict.
Finally, it should be noted that:
although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made on the technical solutions described in the foregoing embodiments, or some or all of the technical features of the embodiments can be equivalently replaced, and the corresponding technical solutions do not depart from the technical solutions of the embodiments of the present invention.
Claims (9)
1. A vinylidene fluoride copolymer containing metal ions, comprising:
the copolymer consists of three compound structural units, namely a polyvinylidene fluoride structural unit (A) consisting of x molar parts of vinylidene fluoride monomers, a acrylamide structural unit (B) consisting of y molar parts of acrylamide monomers and a vinyl lithium carbonate structural unit (C) consisting of z molar parts of vinyl lithium carbonate monomers; and is
The copolymer has the following structural general formula:
among the acrylamide units, it:
r is-H, -CH3、-CH(CH3)2、-CH2CH3、-(CH2)3-OCH3、-CH2-OH、-(CH2)11-CH3、-(CH2)3-N(CH3)2、-C(CH3)3、-CH(CH3)2、-CH2C6H5、-C6H5Any one of the above;
among the vinyl lithium carbonate structural units, it:
n is an integer or a half number of 0 or more;
the respective mole fractions of the polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit are respectively as follows:
x/(x+y+z)＝0.50～0.80，y/(x+y+z)＝0.10～0.40，z/(x+y+z)＝0.10～0.40。
2. the metal ion-containing vinylidene fluoride copolymer of claim 1, wherein:
in the acrylamide structural unit, the following:
r is-H, - (CH)2)3-N(CH3)2、-CH3、-CH(CH3)2Any one of the above;
among the vinyl lithium carbonate structural units, it:
n is any one of 1, 2 and 3;
the respective mole fractions of the polyvinylidene fluoride structural unit, the acrylamide structural unit and the vinyl lithium carbonate structural unit are respectively as follows:
x/(x+y+z)＝0.60～0.80，y/(x+y+z)＝0.10～0.30，z/(x+y+z)＝0.10～0.30。
3. the method for preparing vinylidene fluoride copolymer containing metal ions as claimed in claim 1 or 2, characterized by comprising the steps of:
in a reaction device, adding a vinylidene fluoride monomer, a acrylamide monomer, a vinyl lithium carbonate monomer and an initiator according to respective mole fractions of a polyvinylidene fluoride structural unit, a acrylamide structural unit and a vinyl lithium carbonate structural unit, and copolymerizing by adopting a polymerization reaction method to prepare the vinylidene fluoride copolymer containing the metal ions, wherein the reaction formula is as follows:
4. the method for preparing vinylidene fluoride copolymer containing metal ion as claimed in claim 3, wherein:
the reaction device is a high-pressure reaction kettle;
in the step of respectively adding the vinylidene fluoride monomer, the acrylamide monomer, the vinyl lithium carbonate monomer and the initiator, the method specifically comprises the following steps:
firstly, adding a acrylamide monomer, a vinyl lithium carbonate monomer and an initiator into the high-pressure reaction kettle, repeatedly evacuating to remove oxygen, then filling a vinylidene fluoride monomer gas in a nitrogen atmosphere, and keeping the pressure in the high-pressure reaction kettle between 1.25 and 1.85 MPa;
the step of preparing the vinylidene fluoride copolymer containing the metal ions by copolymerization through a polymerization reaction method specifically comprises the following steps:
slowly heating the materials in the high-pressure reaction kettle to 75-135 ℃, reacting for 12-36 hours by a polymerization reaction method under mechanical stirring, cooling to room temperature, releasing unreacted gas to obtain a vinylidene fluoride copolymer emulsion containing metal ions, demulsifying the emulsion by using an ethanol solution to obtain a broken emulsion, washing the broken emulsion to remove an emulsifier and unreacted vinylidene fluoride monomer, acrylamide monomer and vinyl lithium carbonate monomer, and drying to obtain the vinylidene fluoride copolymer containing metal ions.
5. The method for preparing vinylidene fluoride copolymer containing metal ion as claimed in claim 4, wherein: the initiator is one of benzoyl peroxide, azo compounds or persulfate.
6. The method for preparing vinylidene fluoride copolymer containing metal ion as claimed in claim 4, wherein: the polymerization reaction method is any one of emulsion polymerization, suspension polymerization or aqueous solution polymerization.
7. The method for preparing a vinylidene fluoride copolymer containing a metal ion according to claim 6, wherein: the emulsion polymerization method further comprises an emulsifier, wherein the emulsifier is ammonium perfluorooctanoate.
8. The method for preparing vinylidene fluoride copolymer containing metal ion as claimed in claim 6, wherein: the aqueous phase solution polymerization method further comprises a dispersion medium, wherein the dispersion medium is trifluorotrichloroethane.
9. The method for preparing vinylidene fluoride copolymer containing metal ion as claimed in claim 4, wherein: and after the emulsion is demulsified by an ethanol solution to obtain a demulsified emulsion, dissolving the demulsified solution in an organic solvent to wait for the subsequent washing and drying operation steps, wherein the organic solvent is one or a mixture of more of N, N-dimethylformamide, N-dimethylacetamide, N-methylpyrrolidone, ethanol, isopropanol, dimethyl sulfoxide or ethyl acetate.
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