CN114380930A - Polymer electrolyte, preparation method thereof and battery - Google Patents

Polymer electrolyte, preparation method thereof and battery Download PDF

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CN114380930A
CN114380930A CN202111630191.6A CN202111630191A CN114380930A CN 114380930 A CN114380930 A CN 114380930A CN 202111630191 A CN202111630191 A CN 202111630191A CN 114380930 A CN114380930 A CN 114380930A
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polymer electrolyte
monomer
lithium
battery
polymer
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CN114380930B (en
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黄均庭
李真棠
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Guangdong Carriage Power Technology Co ltd
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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
    • C08F120/00—Homopolymers 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
    • C08F120/02—Monocarboxylic acids having less than ten carbon atoms; Derivatives thereof
    • C08F120/10—Esters
    • C08F120/34—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate
    • C08F120/36—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate containing oxygen in addition to the carboxy oxygen, e.g. 2-N-morpholinoethyl (meth)acrylate or 2-isocyanatoethyl (meth)acrylate
    • 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
    • C08F220/10—Esters
    • C08F220/12—Esters of monohydric alcohols or phenols
    • C08F220/14—Methyl esters, e.g. methyl (meth)acrylate
    • 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
    • C08F220/10—Esters
    • C08F220/34—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate
    • 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
    • C08F220/10—Esters
    • C08F220/34—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate
    • C08F220/36—Esters containing nitrogen, e.g. N,N-dimethylaminoethyl (meth)acrylate containing oxygen in addition to the carboxy oxygen, e.g. 2-N-morpholinoethyl (meth)acrylate or 2-isocyanatoethyl (meth)acrylate
    • 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
    • C08F220/42—Nitriles
    • C08F220/44—Acrylonitrile
    • C08F220/48—Acrylonitrile with nitrogen-containing monomers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0565—Polymeric materials, e.g. gel-type or solid-type
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention discloses a polymer electrolyte, a preparation method thereof and a battery, wherein the polymer electrolyte comprises a polymer matrix, and the polymer electrolyte comprises a polymer matrixThe polymer matrix is formed by polymerizing monomers with the structure shown in the formula (I);
Figure DDA0003439735790000011
wherein A is selected from-F and-CH3-CN or-H; r1Selected from the group containing guanidine, triazazine, triazole or triazole structure; n takes the value of 0 or 1. The polymer matrix in the polymer electrolyte can form a stable five-membered or six-membered ring coordination structure with the transition metal ions dissolved out from the anode material to play a strong chelation role, and the problems of solid electrolyte interface degradation, battery cycle and rate performance reduction caused by the shuttle of the transition metal ions to the cathode interface are effectively solved.

Description

Polymer electrolyte, preparation method thereof and battery
Technical Field
The invention relates to the technical field of batteries, in particular to a polymer electrolyte, a preparation method thereof and a battery.
Background
The lithium ion battery is used as a green chemical power supply with high output voltage, high energy density, no memory effect and environmental friendliness, has good economic benefit, social benefit and strategic significance, and is widely applied to various fields such as mobile communication, consumer digital products, new energy automobiles and the like. With the wide application of power batteries, people have higher and higher requirements on energy density of batteries. At present, a high-nickel NCM ternary material is mainly used as a positive electrode material to improve the energy density of the battery, but in the circulation process of the high-nickel NCM ternary material, the cycle performance and the rate performance of the battery are reduced due to the dissolution of positive electrode transition metal ions, so that the battery is finally failed, and the safety performance of the high-nickel NCM ternary system liquid battery is poor. In order to solve the problem of metal elution of the positive electrode, the main improvement direction at present is to coat the positive electrode to improve the stability of the positive electrode and to add a positive electrode film-forming additive to the liquid electrolyte. The addition of the film-forming additive of the positive electrode can increase the impedance of the battery, reduce the multiplying power and the cycle performance of the battery, and the safety performance of the high-nickel NCM ternary liquid battery is poor. In addition, although the conventional polymer electrolyte can reduce the dissolution of metal ions to a certain extent, most of the metal ions still shuttle to the negative electrode due to the weak chelating action between the polymer matrix and the metal ions (difficult to form stable five-membered ring or six-membered ring coordination), thereby causing the performance reduction of the battery.
Accordingly, the prior art is yet to be improved and developed.
Disclosure of Invention
In view of the above-mentioned shortcomings of the prior art, the present invention aims to provide a polymer electrolyte, a preparation method thereof and a battery, and aims to solve the problem of poor battery cycle performance and rate capability caused by the dissolution of transition metal ions in the prior cathode material.
The technical scheme of the invention is as follows:
in a first aspect of the present invention, a polymer electrolyte is provided, wherein the polymer electrolyte comprises a polymer matrix, and the polymer matrix is formed by polymerizing a monomer having a structure represented by formula (I);
Figure BDA0003439735770000021
wherein A is selected from-F and-CH3-CN or-H;
R1selected from the group containing guanidine, triazazine, triazole or triazole structure;
n takes the value of 0 or 1.
Alternatively, the R is1One selected from the following structures:
Figure BDA0003439735770000022
wherein the content of the first and second substances,
Figure BDA0003439735770000023
indicates the attachment site.
Alternatively, the polymer matrix is formed by homopolymerizing a monomer with a structure shown in formula (I), or the polymer matrix is formed by copolymerizing the monomer with the structure shown in formula (I) and a first monomer.
Optionally, the first monomer is selected from the group consisting of N-monosubstituted acrylamide, acrylonitrile, acrylamide, cyanoacrylate, polyethylene glycol monomethyl ether (meth) acrylate, polyethylene glycol diacrylate, methyl methacrylate, polytetrahydrofuran dimethacrylate, poly (t-butyl methacrylate), poly (ethyl methacrylate), poly (vinyl methacrylate), poly (ethyl methacrylate), and poly (ethyl methacrylate), poly (vinyl methacrylate), and,
Figure BDA0003439735770000031
Acrylic anhydride, acrylic acid anhydride, and acrylic acid anhydride,
Figure BDA0003439735770000032
In (1)One or more of; wherein B is selected from-O-or-NH-, C-Selected from PF6D is selected from-H and-CH3or-F, v is an integer from 1 to 4.
Optionally, the polymer electrolyte further comprises a metal salt, wherein the metal salt comprises one of a lithium salt and a sodium salt, and the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium dioxalate borate, lithium oxalyldifluoroborate, lithium bis-fluorosulfonylimide, lithium bis-trifluoromethylsulfonyl imide, lithium difluorophosphate and lithium 4, 5-dicyano-2-trifluoromethylimidazole; the sodium salt is selected from one or more of sodium perchlorate, sodium hexafluorophosphate, sodium bistrifluorosulfonylimide and sodium bistrifluorosulfonylimide.
Optionally, the polymer electrolyte further comprises an organic additive selected from one or more of ethylene carbonate, ethyl methyl carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl propyl carbonate, butyrolactone, methyl formate, methyl acetate, methyl butyrate, succinonitrile, hexanetricarbonitrile, 4-methyl-1, 3-dioxolane, triethylene glycol dimethyl ether, 1, 2-dimethoxyethane, 1, 3-cyclopentane oxide, 1,3, 5-oxahexane, tetrahydrofuran, vinylene carbonate, ethylene sulfite, fluoroethylene carbonate, propylene sulfite, N-dimethyltrifluoroacetamide.
Optionally, the mass of the metal salt is 0.06% to 40% of the mass of the polymer matrix.
In a second aspect of the present invention, there is provided a method for preparing a polymer electrolyte, comprising the steps of:
the monomer of the present invention having the structure represented by the formula (I) above
Figure BDA0003439735770000033
Mixing with metal salt, and polymerizing monomer to obtain the polymer electrolyte; or, the monomer with the structure shown in the formula (I) is mixed with metal salt and organic additive, and then monomer polymerization is carried out, so as to obtain the polymer electrolyte.
Alternatively, the monomer polymerization is carried out using an initiator initiation method or a uv light initiation method.
In a third aspect of the invention, a battery is provided, wherein the battery comprises the polymer electrolyte as described above, or the battery comprises the polymer electrolyte prepared by the preparation method as described above.
Has the advantages that: the invention provides a polymer electrolyte, a preparation method thereof and a battery, wherein a polymer matrix in the polymer electrolyte can form a stable five-membered or six-membered ring coordination structure with transition metal ions dissolved out from a positive electrode material so as to generate strong chelation, so that the problems of solid electrolyte interface degradation, battery cycle and rate performance reduction caused by the shuttle of the transition metal ions to a negative electrode interface can be solved; because the polymer matrix is Lewis base, the polymer matrix can remove water and acid and has the functions of improving the transference number of lithium ions and reducing the concentration polarization of the battery; meanwhile, the polymer electrolyte has excellent oxidation stability (oxidative decomposition voltage >5.5V) and excellent mechanical properties (tensile strength >20MPa, elongation at break > 200%). The polymer electrolyte can ensure that the battery has good cycle performance, rate capability and safety performance.
Drawings
FIG. 1 is a graph showing the mechanical properties of a polymer electrolyte in example 1 of the present invention.
Fig. 2 is a diagram illustrating a cycle test result of the battery cell in embodiment 2 of the present invention.
Fig. 3 is a diagram illustrating a cycle test result of the battery cell in embodiment 3 of the present invention.
Detailed Description
The present invention provides a polymer electrolyte, a method for preparing the same, and a battery, and the present invention is further described in detail below in order to make the objects, technical solutions, and effects of the present invention clearer and clearer. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The embodiment of the invention provides a polymer electrolyte, wherein the polymer electrolyte comprises a polymer matrix, and the polymer matrix is formed by polymerizing a monomer with a structure shown in a formula (I);
Figure BDA0003439735770000051
wherein A is selected from-F and-CH3-CN or-H;
R1selected from the group containing guanidine, triazazine, triazole or triazole structure;
n takes the value of 0 or 1.
In the polymer matrix of this embodiment, the ester carbonyl group or/and the electron-rich carbamate carbonyl group site, and the electron-rich N site may form a stable five-or six-membered ring coordination structure with the transition metal ions dissolved out from the positive electrode material, so as to play a role in chelating strong transition metal ions, thereby preventing the transition metal ions (e.g., nickel ions, manganese ions, cobalt ions, etc.) dissolved out from the positive electrode material from shuttling to the negative electrode interface. Therefore, the polymer matrix of the embodiment can generate strong chelation with the transition metal ions dissolved out from the anode material through the formed stable five-membered or six-membered ring coordination structure, and effectively solves the problems of solid electrolyte interface degradation, battery cycle and rate performance reduction caused by the shuttle of the transition metal ions to the cathode interface. Because the polymer matrix is Lewis base, the polymer matrix can also remove water and acid and has the functions of improving the transference number of lithium ions and reducing the concentration polarization of the battery. In addition, the use of a polymer electrolyte (solid or semi-solid) having excellent oxidation stability (oxidative decomposition voltage >5.5V) and excellent mechanical properties (tensile strength >20MPa, elongation at break > 200%) can solve the problem of poor safety of the high-nickel ternary liquid battery, which can further improve the safety of the battery.
Specifically, in the charge and discharge cycle process of the battery containing the polymer electrolyte described in this embodiment, transition metal ions eluted from the positive electrode material and N sites and ester carbonyl sites rich in electrons in the polymer matrix, or transition metal ions eluted from the positive electrode material and N sites and carbamate carbonyl sites rich in electrons in the polymer matrix, or transition metal ions eluted from the positive electrode material and N sites, ester carbonyl sites and carbamate carbonyl sites rich in electrons in the polymer matrix form a stable five-membered or six-membered ring coordination structure, which exerts a strong chelating effect on transition metal ions to lock the transition metal ions in the polymer electrolyte, so that the transition metal ions eluted from the positive electrode material cannot shuttle to the surface of the negative electrode, thereby improving the cycle and rate performance of the battery.
In this embodiment, A is selected from the group consisting of-F and-CH3-CN or-H. These groups ensure that the polymerization reaction is carried out>A monomer conversion of 99.5% and a selected from-F groups can impart excellent flame retardancy to the electrolyte.
In one embodiment, the R is1One selected from the following structures:
Figure BDA0003439735770000061
Figure BDA0003439735770000062
wherein the content of the first and second substances,
Figure BDA0003439735770000063
indicates the attachment site.
In this embodiment, R1One selected from the above-mentioned structures, on the one hand, can ensure>99.5 percent of monomer conversion rate, avoids interface instability failure (including a positive electrode/electrolyte interface and a negative electrode/electrolyte interface) caused by excessive monomer residues, is intrinsically strong in Lewis basicity, can remove acidic substances (mainly from water or electrolyte decomposition) generated in the battery, and avoids performance reduction and potential safety hazard of the battery caused by the acidic substances.
In one embodiment, the polymer matrix is formed by homopolymerizing a monomer having a structure represented by formula (I), or copolymerizing a monomer having a structure represented by formula (I) with a first monomer. In specific implementation, the polymer matrix is obtained by polymerizing 10-100% by mass of a monomer with a structure shown in a formula (I) and 0-90% by mass of a first monomer. For example, the polymer matrix is obtained by polymerizing 10 mass percent of monomer with a structure shown in a formula (I) and 90 mass percent of first monomer; the polymer matrix is obtained by polymerizing 20 mass percent of monomer with a structure shown in a formula (I) and 80 mass percent of first monomer; for example, the polymer matrix is obtained by polymerizing 90 mass percent of a monomer with a structure shown in a formula (I) and 10 mass percent of a first monomer.
When the polymer matrix is composed of
Figure BDA0003439735770000071
When homopolymerized, it has the structural formula
Figure BDA0003439735770000072
Wherein x is polymerization degree and takes the value of 50-2000.
In one embodiment, the first monomer is selected from the group consisting of N-monosubstituted acrylamide, Acrylonitrile (AN), Acrylamide (AM), cyanoacrylate (ECA), polyethylene glycol monomethyl ether (meth) acrylate, polyethylene glycol diacrylate, methyl methacrylate, polytetrahydrofuran dimethacrylate, poly (ethylene glycol) methyl methacrylate, poly (ethylene glycol) ethyl acrylate, poly (ethylene glycol) s, and poly (ethylene glycol) s,
Figure BDA0003439735770000073
Acrylic anhydride, acrylic acid anhydride, and acrylic acid anhydride,
Figure BDA0003439735770000074
(v is an integer of 1 to 4),
Figure BDA0003439735770000075
(v is an integer of 1 to 4),
Figure BDA0003439735770000076
But are not limited thereto; wherein B is selected from-O-or-NH-, C-Selected from PF6D is selected from-H and-CH3or-F,.
By way of example, when the first monomer is selected from acrylonitrile, it is reacted with
Figure BDA0003439735770000077
The structure formula of the polymer matrix obtained by copolymerization is shown in the specification
Figure BDA0003439735770000078
Wherein x and y are polymerization degrees, the value of x is 50-2000, and the value of y is 1-1000.
In one embodiment, the polymer electrolyte further comprises a metal salt, the metal salt comprises one of a lithium salt and a sodium salt, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium dioxalate borate, lithium oxalatedifluoroborate, lithium bis-fluorosulfonylimide, lithium bis-trifluoromethylsulfonylimide, lithium difluorophosphate, lithium 4, 5-dicyano-2-trifluoromethylimidazolium, but is not limited thereto; the sodium salt is selected from one or more of sodium perchlorate, sodium hexafluorophosphate, sodium bistrifluorosulfonylimide and sodium bistrifluorosulfonylimide, but is not limited thereto.
In one embodiment, the metal salt is present in an amount of 0.06% to 40% by mass of the polymer matrix. This ratio can give polymer electrolyte membranes having excellent oxidative stability (oxidative decomposition voltage >5.5V) and excellent mechanical properties (tensile strength >20MPa, elongation at break > 200%).
In one embodiment, the polymer electrolyte further includes an organic additive selected from one or more of ethylene carbonate, ethyl methyl carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl propyl carbonate, butyrolactone, methyl formate, methyl acetate, methyl butyrate, succinonitrile, hexanetricarbonitrile, 4-methyl-1, 3-dioxolane, triethylene glycol dimethyl ether, 1, 2-dimethoxyethane, 1, 3-epoxypentane, 1,3, 5-oxahexane, tetrahydrofuran, vinylene carbonate, ethylene sulfite, fluoroethylene carbonate, propylene sulfite, N-dimethyltrifluoroacetamide, but not limited thereto. In specific implementation, the mass of the organic additive accounts for 0-98% of the sum of the mass of the organic additive and the mass of the metal salt. Further, in particular implementations, the polymer electrolyte includes a polymer matrix, a metal salt, and an organic additive.
In one embodiment, the polymer electrolyte may further include an inorganic fast ion conductor including one or more of an oxide-based electrolyte, a sulfide-based electrolyte (e.g., lipsccl), a phosphate, an anti-perovskite material, but is not limited thereto. In specific implementation, the mass of the inorganic fast ion conductor accounts for 0-98% of the sum of the mass of the inorganic fast ion conductor and the mass of the metal salt. Further, in particular implementations, the polymer electrolyte includes a polymer matrix, a metal salt, and an inorganic fast ion conductor. In further embodiments, the polymer electrolyte includes a polymer matrix, a metal salt, an inorganic fast ion conductor, and an organic additive.
The embodiment of the invention also provides a preparation method of the polymer electrolyte, which comprises the following steps:
the monomer of the present invention having the structure represented by the formula (I) in the above embodiment
Figure BDA0003439735770000091
Mixing with metal salt, and polymerizing monomer to obtain the polymer electrolyte; or, the monomer of the present invention having the structure represented by formula (I) in the above embodiment
Figure BDA0003439735770000092
And mixing the electrolyte with metal salt and organic additive, and polymerizing the monomer to obtain the polymer electrolyte.
In one embodiment, the monomer of the present invention having a structure represented by formula (I) in the above example
Figure BDA0003439735770000093
The step of mixing with metal salt and organic additive also includes adding inorganic fast ion conductor.
In one embodiment, the monomer polymerization is carried out using an initiator-initiated process or a UV light initiated process.
When an initiator initiation process is employed, monomers of the present invention having the structure shown in formula (I) in the above example are prepared
Figure BDA0003439735770000094
And mixing the initiator with metal salt (or metal salt and organic additive), and polymerizing the monomer to obtain the polymer electrolyte.
When the ultraviolet light initiation method is adopted, the monomer with the structure shown in the formula (I) in the embodiment of the invention is used
Figure BDA0003439735770000095
And (3) mixing metal salt (or metal salt and organic additive), and polymerizing the monomer to obtain the polymer electrolyte.
In one embodiment, the initiator used in the initiator initiation method is azobisisobutyronitrile, peroxybenzoic acid, or a mixture of azobisisobutyronitrile and a reversible addition-fragmentation chain transfer (RAFT) reagent, but is not limited thereto.
In one embodiment, the amount of the initiator is 0 to 5% by mass of the polymer matrix.
The embodiment of the invention also provides a battery, wherein the battery comprises the polymer electrolyte provided by the invention in the embodiment, or the battery comprises the polymer electrolyte prepared by the preparation method provided by the invention in the embodiment.
In one embodiment, the battery is a lithium ion battery, a sodium ion battery, a lithium metal battery, a sodium metal battery, a lithium sulfur battery, or a sodium sulfur battery, but is not limited thereto.
In one embodiment, the battery further comprises a positive electrode comprising a positive active material, the positive active material may be selected from one or more of lithium cobaltate, lithium nickel manganese oxide, lithium iron phosphate, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, sulfur, or the positive active material is selected from organic conjugated material, sodium vanadium phosphate, NaMnPO4、NaFePO4、NaxMO4(M ═ Co, Mn, V, or Fe) and sulfur.
In one embodiment, the positive electrode further includes a conductive agent, and the conductive agent may be selected from one or more of conductive carbon black, acetylene black, superconducting carbon black (ketjen black), conductive graphite, conductive carbon fiber, carbon nanotube, graphene, metal powder, and carbon fiber, but is not limited thereto.
In one embodiment, the positive electrode further includes a binder, and the binder may be selected from one or more of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, acrylonitrile, acrylate, and polyethylene oxide, but is not limited thereto.
In one embodiment, the positive electrode comprises, in mass percent:
60-99 wt% of positive active material, 0.1-25 wt% of conductive agent and 0.1-25 wt% of binder, and the sum of the three is 100 wt%.
In one embodiment, the battery further includes a negative electrode including a negative active material, which may be selected from one or more of artificial graphite, natural graphite, mesocarbon microbeads, soft carbon, hard carbon, silicon-based materials (including silicon negative materials, silicon oxygen negative materials, silicon carbon negative materials), graphite-silicon composite materials, lithium titanate, sodium titanate, two-dimensional metal carbides, two-dimensional metal nitrides, lithium metal and alloys thereof, sodium metal and alloys thereof, but is not limited thereto.
In one embodiment, the negative electrode further includes a conductive agent, and the conductive agent may be selected from one or more of conductive carbon black, acetylene black, superconducting carbon black (ketjen black), conductive graphite, conductive carbon fiber, carbon nanotube, graphene, metal powder, and carbon fiber, but is not limited thereto.
In one embodiment, the negative electrode further includes a binder, and the binder may be selected from one or more of sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, polyvinylidene fluoride, acrylic acid, acrylonitrile, acrylate, and polyethylene oxide, but is not limited thereto.
In one embodiment, the negative electrode comprises, in mass percent:
60-99 wt% of negative electrode active material, 0.1-25 wt% of conductive agent and 0.1-25 wt% of binder, and the sum of the three is 100 wt%.
In one embodiment, the battery may further include a separator, which may be selected from, but not limited to, an uncoated or ceramic-coated or ceramic + glue-coated PP, PE, PP/PE separator.
In a specific embodiment, the separator is disposed between the positive electrode and the negative electrode, and the polymer electrolyte is filled between the positive electrode and the negative electrode.
The invention is further illustrated by the following specific examples.
Unless otherwise specified, the experimental methods used in the following examples are all conventional methods; the reagents, materials, instruments and the like used in the following examples and comparative examples are all conventional reagents, conventional materials and conventional instruments.
Example 1
Preparing a positive plate: adding an NCM523 ternary material, acetylene black and polyvinylidene fluoride into a stirring tank according to the mass ratio of 95.5:2.5:2, adding an N-methylpyrrolidone solvent, uniformly stirring, and sieving with a 200-mesh sieve to prepare anode active material layer slurry with the solid content of 75 wt%; coating the slurry on a positive current collector (aluminum foil) by using a coating machine, drying at 120 ℃, and rolling to obtain the positive plate.
Preparing a negative plate: mixing graphite (solid phase diffusion coefficient of 10) with a mass ratio of 95:2:1.2:1.8-14cm2·s-1) Adding conductive carbon black, CMC and SBR into a stirring tank, adding deionized water, stirring uniformly, and sieving with a 200-mesh sieve to prepare cathode active material layer slurry with a solid content of 45 wt%; coating the slurry on a negative current collector (copper foil) by using a coating machine, drying at 100 ℃, and rolling to obtain a negative plate.
Preparation of polymer electrolyte precursor solution: according to the following steps of 20: 60: 19.9: 0.1 mass ratio of the monomers to be polymerized
Figure BDA0003439735770000121
And uniformly mixing succinonitrile, lithium hexafluorophosphate and azobisisobutyronitrile, and preparing to obtain the polymer electrolyte precursor solution.
Assembling the battery cell: and (3) laminating the prepared negative plate, the positive plate and the diaphragm together to form a laminated core (the design capacity is 10Ah), packaging by using an aluminum-plastic film, baking at 85 ℃ to remove moisture, injecting the polymer electrolyte precursor solution, treating at 80 ℃ for 12h, (at the temperature, the polymer electrolyte precursor solution can be polymerized into polymer electrolyte), and performing hot pressing to obtain the battery core.
Example 2
The only difference from the cell preparation process in example 1 is that:
the positive electrode is made of NCM622 material;
according to the following steps: 5: 80: 9.5: 0.5 mass ratio of
Figure BDA0003439735770000122
And uniformly mixing acrylonitrile, propylene carbonate, LiDFOB and benzoyl peroxide, and preparing to obtain the polymer electrolyte precursor solution.
Example 3
The only difference from the cell preparation process in example 1 is that:
the anode is made of lithium cobaltate material;
according to the following steps: 9: 85: 4: 1, by mass ratio of
Figure BDA0003439735770000123
And uniformly mixing methyl methacrylate, LiPSCl, lithium hexafluorophosphate and azobisisobutyronitrile, and preparing to obtain the polymer electrolyte precursor solution.
Example 4
The only difference from the cell preparation process in example 1 is that the following steps were performed in the order of 9: 1: 85: 4: 1, by mass ratio of
Figure BDA0003439735770000124
Uniformly mixing acrylic anhydride, diethyl carbonate, lithium hexafluorophosphate and benzoyl peroxide, and preparing to obtain the polymer electrolyte precursor solution.
Comparative example 1
The only difference from the cell preparation process of example 2 is that a commercially available conventional liquid electrolyte was used.
Testing
1. The cell of example 1 was disassembled, and the polymer electrolyte was removed for mechanical property testing. As a result, as shown in FIG. 1, the tensile strength of the resulting polymer electrolyte membrane was 23MPa, and the elongation at break was 352%.
2. The cell of example 2 was subjected to a cycle test (voltage interval: 2.8-4.2V, charging current 1.0C, discharging current 1.0C). The results are shown in fig. 2, and it can be seen from fig. 2 that the NCM 622/graphite battery assembled with the electrolyte circulates 400 cycles, the capacity is kept at 96%, the average coulombic efficiency is 99.91%, and the battery has better cycle performance.
3. The battery core in example 3 was subjected to a cycle test (voltage interval: 2.8-4.4V, charging current 2.0C, and discharging current 2.0C), and as shown in fig. 3, it can be seen from fig. 3 that after the assembled lithium cobaltate/graphite battery was cycled for 200 cycles at room temperature, the capacity was maintained at 97%, the average coulombic efficiency was 99.92%, and the battery had better cycle performance.
4. After the cyclic example 2 and the comparative example 1 are discharged to 2.8V and then disassembled, and the cathode sheets of the two are respectively subjected to an inductively coupled plasma mass spectrometry (ICP-MS) test, the result shows that the cathode sheet in the comparative example 1 has a large amount of elements such as Ni, Mn, Co and the like, while the cathode sheet in the example 2 almost has no elements such as Ni, Mn, Co and the like, which fully shows that the example 2 of the invention can effectively inhibit the dissolution and migration of the cathode metal to the cathode.
In summary, the invention provides a polymer electrolyte, a preparation method thereof and a battery, wherein a polymer matrix in the polymer electrolyte can form a stable five-membered or six-membered ring coordination structure with transition metal ions dissolved out from a positive electrode material to generate strong chelation, so that the problems of solid electrolyte interface degradation, battery cycle and rate performance reduction caused by shuttling of the transition metal ions to a negative electrode interface are effectively solved; because the polymer matrix is Lewis base, the polymer matrix can remove water and acid and has the functions of improving the transference number of lithium ions and reducing the concentration polarization of the battery; meanwhile, the polymer electrolyte has excellent oxidation stability (oxidative decomposition voltage >5.5V) and excellent mechanical properties (tensile strength >20MPa, elongation at break > 200%). The polymer electrolyte can ensure that the battery has good cycle performance, rate capability and safety performance.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (10)

1. A polymer electrolyte is characterized by comprising a polymer matrix, wherein the polymer matrix is formed by polymerizing a monomer with a structure shown in a formula (I);
Figure FDA0003439735760000011
wherein A is selected from-F and-CH3-CN or-H;
R1selected from the group containing guanidine, triazazine, triazole or triazole structure;
n takes the value of 0 or 1.
2. The polymer electrolyte of claim 1, wherein R is1One selected from the following structures:
Figure FDA0003439735760000012
wherein the content of the first and second substances,
Figure FDA0003439735760000013
indicates the attachment site.
3. The polymer electrolyte of claim 1, wherein the polymer matrix is formed by homopolymerizing a monomer having a structure represented by formula (i), or copolymerizing a monomer having a structure represented by formula (i) with a first monomer.
4. The polymer electrolyte of claim 3, wherein the first monomer is selected from the group consisting of N-monosubstituted acrylamide, acrylonitrile, acrylamide, cyanoacrylate, polyethylene glycol monomethyl ether (meth) acrylate, polyethylene glycol diacrylate, methyl methacrylate, polytetrahydrofuran dimethacrylate, poly (t-butyl methacrylate), and poly (t-butyl acrylate), and the polymer electrolyte,
Figure FDA0003439735760000021
Acrylic anhydride, acrylic acid anhydride, and acrylic acid anhydride,
Figure FDA0003439735760000022
Figure FDA0003439735760000023
One or more of; wherein B is selected from-O-or-NH-, C-Selected from PF6 -D is selected from-H and-CH3or-F, v is an integer from 1 to 4.
5. The polymer electrolyte of claim 1, further comprising a metal salt, wherein the metal salt comprises one of a lithium salt and a sodium salt, and the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium dioxalate borate, lithium oxalyldifluoroborate, lithium bis fluorosulfonylimide, lithium bis-trifluoromethylsulfonyl imide, lithium difluorophosphate, and lithium 4, 5-dicyano-2-trifluoromethylimidazole; the sodium salt is selected from one or more of sodium perchlorate, sodium hexafluorophosphate, sodium bistrifluorosulfonylimide and sodium bistrifluorosulfonylimide.
6. The polymer electrolyte of claim 5, further comprising an organic additive selected from one or more of ethylene carbonate, ethyl methyl carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methylpropyl carbonate, butyrolactone, methyl formate, methyl acetate, methyl butyrate, succinonitrile, hexanetricarbonitrile, 4-methyl-1, 3-dioxolane, triethylene glycol dimethyl ether, 1, 2-dimethoxyethane, 1, 3-cyclopentane oxide, 1,3, 5-oxahexane, tetrahydrofuran, vinylene carbonate, ethylene sulfite, fluoroethylene carbonate, propylene sulfite, N-dimethyltrifluoroacetamide.
7. The polymer electrolyte of claim 5, wherein the metal salt is present in an amount of 0.06-40% by mass based on the mass of the polymer matrix.
8. A method for preparing a polymer electrolyte, comprising the steps of:
mixing a monomer having a structure represented by the formula (I) in claim 1 with a metal salt, and polymerizing the monomer to obtain the polymer electrolyte; or, the polymer electrolyte is obtained by mixing a monomer having a structure represented by formula (I) in claim 1 with a metal salt and an organic additive and then polymerizing the monomer.
9. The method of claim 8, wherein the monomer is polymerized by an initiator initiation method or a UV light initiation method.
10. A battery comprising the polymer electrolyte according to any one of claims 1 to 7, or a polymer electrolyte produced by the production method according to any one of claims 8 to 9.
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