CN114649570B

CN114649570B - A polymerizable electrolyte and its preparation method and application

Info

Publication number: CN114649570B
Application number: CN202011491494.XA
Authority: CN
Inventors: 俞会根; 杨萌; 程勇斌
Original assignee: Beijing Weilan New Energy Technology Co ltd
Current assignee: Beijing Weilan New Energy Technology Co ltd
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2024-11-26
Anticipated expiration: 2040-12-17
Also published as: CN114649570A

Abstract

The present application provides a polymerizable electrolyte and a preparation method and application thereof. The electrolyte includes a boron trifluoride salt, and the structure of the boron trifluoride salt is shown in general formula I. The electrolyte provided in the present application has a polymerizable group and a functionalized group, so that it has a variety of applications in batteries. It can be used as a functional additive to form a passivation film on the electrode surface to prevent the electrode from decomposing the components of the electrolyte; it can be used as a main salt, the main function of which is to provide the battery with transportable ions, and the secondary function is to form a passivation film on the electrode surface; it can be polymerized in situ/ex situ to form a single ion conductor polymer electrolyte and a polymer skeleton application, providing the battery with higher ionic conductivity, higher electrochemical stability, and better mechanical properties. Therefore, the battery prepared from the electrolyte has excellent long cycle stability, good battery life, and the raw material price is low, with good economic benefits.

Description

Polymerizable electrolyte and preparation method and application thereof

Technical Field

The application relates to the technical field of batteries, in particular to a polymerizable electrolyte and a preparation method and application thereof.

Background

The secondary battery has the advantages of high energy density, long service life, no memory effect and the like, so that the secondary battery is rapidly developed and has wider application range. At present, the secondary battery mainly comprises a liquid battery, but the liquid battery has low energy density and poor safety. Mainly because the electrochemical window of the liquid electrolyte used at present is narrower, the liquid electrolyte cannot be matched with high-voltage anode materials (such as high-voltage lithium cobalt oxide, lithium nickel manganese oxide and the like) for use; the boiling point of the organic solvent is low, so that the organic solvent is easy to leak liquid, and the risks of fire explosion and the like occur; conventional salts are easy to decompose at high temperature (such as lithium hexafluorophosphate), are easy to corrode aluminum foils (such as lithium bis (trifluoromethyl) sulfonimide and lithium bis (fluorosulfonyl) imide), and are easy to produce gas (such as lithium difluorooxalate phosphate), so that the service life of the battery is influenced.

The prior solution method mainly comprises two steps, namely, a layer of passivation film can be formed on the surface of an electrode by adding some functional additives into the liquid electrolyte, so that the catalytic decomposition of the liquid electrolyte by the electrode is effectively relieved, but the passivation layer formed on the surface of the electrode by decomposing the conventional functional additives is not compact, and ions from an anode are consumed in the process of forming the passivation layer, so that the first-week efficiency and the specific volume of discharge are low. Secondly, solid-state batteries are developed, namely, the liquid electrolyte for transmitting ions is replaced by the solid-state electrolyte, so that the safety of the battery is greatly improved by the solid-state electrolyte, thermal runaway is not easy to occur, and the high-temperature stability is good. The solid electrolyte commonly used at present comprises oxide electrolyte, sulfide electrolyte and polymer electrolyte, wherein the electrochemical window of the oxide electrolyte is wider, but the rigidity is too strong; sulfide electrolyte has plasticity, but has a narrow electrochemical window and is extremely easy to generate hydrogen sulfide gas; the polymer electrolyte has good mechanical properties, but has lower ionic conductivity and low ion migration number. Worldwide, all solid-state batteries are in a starting stage, and still cannot achieve high energy density, long cycle and intrinsic safety. At present, more solid-liquid and gel batteries are mixed, and the advantages of the liquid battery and the all-solid battery can be considered, however, the disadvantages of the liquid electrolyte still determine the performance of the battery. Therefore, there is an urgent need to develop an additive which has good heat stability, stable passivation layer and provides ions by itself, develop new salts with good stability and high conductivity, and develop single ion conductors with high ion conductivity and high migration number.

Disclosure of Invention

In view of the above, the embodiments of the present application provide a polymerizable electrolyte, and a preparation method and application thereof, so as to solve the technical defects existing in the prior art.

The application provides a polymerizable electrolyte, which comprises boron trifluoride salt, wherein the structure of the boron trifluoride salt is shown as a general formula I:

Wherein, R ⁺ is selected from any one of positive monovalent metal cations, R ₁ is selected from any one of blank, first ring or chain containing substituent or not containing substituent, and R ₂ is selected from second ring which contains substituent or not containing substituent and can be polymerized;

The first ring includes a ring composed of carbon atoms and a ring containing at least one heteroatom, the chain includes a chain composed of only carbon atoms and a chain containing at least one heteroatom, and the substituents include cyclic substituents, chain substituents, and halogen atoms.

Further, R ⁺ is selected from any one of sodium ion, lithium ion and potassium ion;

The first ring is a three-membered ring-sixteen membered ring, the first ring comprises a saturated carbocycle, an unsaturated carbocycle, a saturated heterocycle and an unsaturated heterocycle, the chain is a chain consisting of 1-20 atoms, the chain consisting of carbon atoms only and the chain containing at least one heteroatom both comprise a saturated chain and an unsaturated chain containing an unsaturated bond, and the unsaturated bond comprises a double bond and/or a triple bond;

The second ring is a three-membered ring-ten-membered ring, and the second ring is selected from any one of cycloolefin, cyclic ether, cyclic acetal, cyclic ester, cyclic anhydride, cyclic carbonate, cyclic amide, cyclic amine, cyclic thioether, cyclic disulfide, cyclosiloxane and cyclophosphazene;

The cyclic substituent includes a substituted or unsubstituted three-membered to twenty-membered ring, and a polycyclic substituent having two or more ring structures at the same time;

the chain substituent includes substituted or unsubstituted alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, alkinyl, alkylthio, c=o-containing substituent, =o, =s.

Further, in the case where R ₂ is selected from cycloolefins, R ₂ is a four-membered ring, a five-membered ring, a seven-membered ring, an eight-membered ring, a nine-membered ring, or a ten-membered ring which may have a substituent;

In the case where R ₂ is selected from cyclic ethers, R ₂ is a three-, four-, five-or seven-membered ring with or without substituents;

in the case where R ₂ is selected from cyclic acetals, R ₂ is a six-membered or eight-membered ring with or without substituents;

In the case where R ₂ is selected from cyclic esters, R ₂ is a four-, six-, seven-or eight-membered ring with or without substituents;

In the case where R ₂ is selected from cyclic anhydrides, R ₂ is a five-, seven-or eight-membered ring with or without substituents;

In the case where R ₂ is selected from cyclic carbonates, R ₂ is a six-to eight-membered ring with or without substituents;

In the case where R ₂ is selected from cyclic amides, R ₂ is a four-membered to eight-membered ring with or without substituents;

In the case where R ₂ is selected from cyclic amines, R ₂ is a three-, four-or seven-membered ring with or without substituents;

In the case where R ₂ is selected from cyclic sulfides, R ₂ is a three-or four-membered ring with or without substituents;

In the case where R ₂ is selected from cyclodisulfide, R ₂ is a four-membered to eight-membered ring with or without substituents;

In the case where R ₂ is selected from cyclosiloxanes, R ₂ is a six-, eight-, or ten-membered ring with or without substituents;

In the case where R ₂ is selected from cyclophosphazene, R ₂ is a six-membered ring containing a substituent or not.

Further, where R ₂ is selected from cycloalkenes, the structure of formula I includes:

in the case where R ₂ is selected from cyclic ethers, the structure of formula I includes:

In the case where R ₂ is selected from cyclic acetals, the structure of formula I includes:

In the case where R ₂ is selected from cyclic esters, the structure of formula I includes:

in the case where R ₂ is selected from cyclic anhydrides, the structure of formula I includes:

in the case where R ₂ is selected from cyclic carbonates, the structure of formula I includes:

in the case where R ₂ is selected from cyclic amides, the structure of formula I includes:

in the case where R ₂ is selected from cyclic amines, the structure of formula I includes:

in the case where R ₂ is selected from cyclic sulfides, the structure of formula I includes:

In the case where R ₂ is selected from the group consisting of cyclodithio, the structure of formula I includes:

in the case where R ₂ is selected from cyclosiloxanes, the structure of formula I includes:

In the case where R ₂ is selected from cyclophosphazene, the structure of formula I includes:

wherein Q represents

R ₃、R₄、R₅、R₆、R₇、R₈、R₉、R₁₀ is selected from any one or a combination of a plurality of hydrogen atoms, rings or chains containing substituent groups or not containing substituent groups, halogen atoms and metal cations.

Further, the chain substituent includes a hydrogen atom, a halogen atom, an ether oxygen bond/group, an ether sulfur bond/group, a nitro group, an amide, a sulfonamide group, a sulfo group, a sulfonic acid group, a salt substituent, a c=o substituent, an N substituent, an alkyl group, a heteroalkyl group, an alkenyl group, a heteroalkenyl group, an alkynyl group, an alkinyl group, =o, =s;

the cyclic substituent comprises a ternary ring, a quaternary ring, a five-membered ring, a six-membered ring, a seven-membered ring, an eight-membered ring and a polycyclic substituent simultaneously containing two or more ring structures;

the halogen atom includes chlorine atom, bromine atom, iodine atom and fluorine atom.

Further, the substituents include:

Hydrogen atom, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group, isopentyl group, sec-pentyl group, neopentyl group, n-hexyl group, isohexyl group, sec-hexyl group, neohexyl group, n-heptyl group, isoheptyl group, neoheptyl group, n-octyl group, isooctyl group, sec-octyl group, neooctyl group, vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, heptenyl group, ethynyl group, propynyl group, butynyl group, pentynyl group, hexynyl group, heptynyl group, cyclohexyl group, cyclopentyl group, phenyl group, ester group, sulfoalkyl group, amide group, sulfonamide group, sulfonyl group, sulfonic group, aldehyde group, ether oxygen bond/group, ether sulfur bond/group, nitro group 、-COOCH₃、COOCH₂CH₃、-SCH₃、＝O、-N(CH₃)₂、-CO-N(CH₃)₂、-S-、-O-、

Further, all or part of the hydrogen atoms on all carbon atoms in any one of the general formulas I are independently substituted with halogen atoms;

preferably, all or part of the hydrogen atoms on all carbon atoms in any one of the formulae I are independently replaced by fluorine atoms.

The present application also provides a process for preparing a polymerizable electrolyte according to any one of the above paragraphs, which comprises reacting a monomer containing an-OH group, a boron trifluoride compound and a source of R ⁺ to give a product, i.e., a polymer containing an organic compoundBoron trifluoride salt structure of (a).

The present application also provides a use of the polymerizable electrolyte according to any one of the preceding paragraphs in a secondary battery, the use being: the boron trifluoride salt can be used as an additive of an electrolyte, can be used as a salt, and can be used as a single-ion conductor and a polymer frame after a monomer containing a polymerizable group is polymerized.

Further, the applications include applications in liquid electrolytes, gel electrolytes, mixed solid-liquid electrolytes, quasi-solid electrolytes, all-solid electrolytes, each independently including the electrolyte described in any one of the above paragraphs;

preferably, the use further comprises use as a battery or battery pack comprising an electrolyte as described in any of the preceding paragraphs, and a positive electrode, a negative electrode and a packaging housing; the liquid electrolyte, gel electrolyte, mixed solid-liquid electrolyte, quasi-solid electrolyte, and all-solid electrolyte may be applied to a liquid battery, a mixed solid-liquid battery, a semi-solid battery, a gel battery, a quasi-solid battery, and an all-solid battery, the battery pack including the batteries.

The technical effects are as follows:

The boron-containing organic compound provided by the application can be used as an additive in a battery, can form a stable and compact passivation film on the surface of an electrode of the battery, prevents electrolyte from being in direct contact with electrode active substances, inhibits decomposition of each component of the electrolyte, widens an electrochemical window of the whole electrolyte system, and can obviously improve the specific discharge capacity, coulomb efficiency and cycle performance of the battery; in addition, the boron-containing organic compound is an ion conductor, and is used as an additive, so that a passivation layer is formed on the surface of an electrode, active ions separated from a positive electrode are less consumed, and the first coulomb efficiency and the first-week discharge specific capacity of the battery can be obviously improved. And when the electrolyte containing the boron-containing organic compound, the existing high-voltage high-specific-volume positive electrode material and the low-voltage high-specific-volume negative electrode material are compounded into the battery, the electrochemical performance of the battery is improved. In addition, the structure of the present application can be used in combination with conventional additives, i.e., dual or multi-additive, and batteries using the dual or multi-additive exhibit more excellent electrochemical performance.

The boron-containing organic compound provided by the application can be used as main salt in a battery, and contained ions are easier to dissociate, so that the ion conductivity is higher, and the electrochemical performance of the assembled battery is excellent.

If the boron-containing organic compound provided by the application contains a polymerizable group, the boron-containing organic compound can also form a single-ion conductor and polymer skeleton after polymerization, so that good ion conductivity, good mechanical property and good comprehensive performance of the battery can be provided.

In addition, the boron trifluoride salt has the advantages of abundant raw material sources, wide raw material selectivity, low cost, simple preparation process, mild reaction conditions and excellent industrial application prospect.

In addition, the application can also adopt metals such as sodium, potassium and the like except for traditional lithium to form salt, which provides more possibility for later application, cost control or raw material selection and the like of the application, and has great significance.

Therefore, the polymerizable electrolyte provided by the application can be applied to liquid batteries, mixed solid-liquid batteries, gel batteries, quasi-solid batteries and all-solid batteries, can improve the electrochemical performance of the batteries, and has the advantages of improving the energy density of the batteries, improving the circulation stability, prolonging the service life of the batteries, along with simple synthesis process, low raw material price and good economic benefit.

Drawings

FIGS. 1 to 12 are nuclear magnetic resonance hydrogen spectra of the products shown in examples 1 to 12;

FIGS. 13 to 16 are graphs showing the effect of the cells 1/6/9/14 prepared from examples 1/6/9/14 as liquid electrolyte additives, respectively, compared with the corresponding comparative cells 1/4/7/11 not containing the examples of the present invention;

FIGS. 17 to 18 are graphs showing the effect of the battery 1/7 of example 1/7 as a liquid electrolyte salt and the corresponding comparative battery 1/7 not containing the example of the present invention, respectively;

fig. 19 is an effect diagram of the polymer electrolyte battery 2 produced by polymerizing the monomer in example 2;

fig. 20 is an effect diagram of the polymer electrolyte battery 10 produced by polymerizing the monomer in example 10.

Detailed Description

The following describes specific embodiments of the present application with reference to the drawings.

In the present invention, unless otherwise indicated, scientific and technical terms used herein have the meanings commonly understood by one of ordinary skill in the art. Also, reagents, materials, and procedures used herein are reagents, materials, and conventional procedures widely used in the corresponding field. Meanwhile, in order to better understand the present invention, definitions and explanations of related terms are provided below.

In the present invention, if a group is required to be linked to a two-part structure, it has two linkages to be linked, and if it is not explicitly indicated which two atoms are linked to the linked part, any one of the atoms containing H may be linked.

In the present invention, if one C contains a plurality of H, any one or several of the plurality of H may be substituted with a substituent, or all of the H may be substituted with a substituent, and in the case where two or more H are substituted with a substituent, the substituents may be the same or different. Such asR ₀₁ and R ₀₂ each represent C to which they are attached, which may be substituted with either one or two substituents, e.g. if R ₀₁ is methyl and R ₀₂ is F, the above structures may beIf R ₀₁ is H and R ₀₂ is methyl or F, the above structure may be

In the present invention, if the chemical bond is not drawn on an atom, but is drawn at a position intersecting the bond, e.g.Any H on the cyclohexane can be substituted by a substituent R ₀₄, and can be substituted by one H or two or more H, and the substituents can be the same or different. If two H are contained in one C of cyclohexane, the two H may be substituted by all substituents, or may be substituted by only 1, for example, both H may be substituted by methyl, or one may be substituted by methyl, and one may be substituted by ethyl. In addition, substituents may also be attached to the ring by double bonds. For example, in this structure, if R ₀₄ is methyl, = O, F, the above structure may be

The "Et" is ethyl, and the "Ph" is phenyl.

In the structural formula of the present invention, if a group located in a bracket "()" is contained after a certain atom, it means that the group in the bracket is linked to the atom in front of it. For example-C (CH ₃)₂ -is-CH (CH ₃) -is

The "boron trifluoride-like compound" means boron trifluoride, a compound containing boron trifluoride, a boron trifluoride complex or the like.

The invention provides a monobasic organic boron trifluoride salt which is useful as an electrolyte additive, electrolyte salt and polymerizable monomer, namely, is contained in the organic matterA group, wherein R ⁺ may be Li ⁺、Na⁺ or the like. The boron trifluoride salt can be applied to liquid batteries, mixed solid-liquid batteries, semi-solid batteries, gel batteries, quasi-solid batteries and all-solid batteries. The preparation method of the compound is simple and ingenious, and the yield is high. Namely, raw materials, boron trifluoride compounds and an R ⁺ source react to obtain the boron trifluoride compound, specifically, the-OH in the raw materials participates in the reaction, and other structures do not participate in the reaction. The specific preparation method mainly comprises two steps:

1. Adding the R ⁺ source and the raw materials into a solvent under the nitrogen/argon atmosphere, mixing, reacting for 3-24 hours at 5-60 ℃, and drying the obtained mixed solution under reduced pressure at 20-80 ℃ and a vacuum degree of about-0.1 MPa to remove the solvent to obtain an intermediate; then adding boron trifluoride compound, stirring at 5-60 ℃ for reaction for 6-24 hours, drying the obtained mixed solution under reduced pressure at 20-80 ℃ and a vacuum degree of about-0.1 MPa to obtain a crude product, washing, filtering and drying the crude product to obtain the final product of unitary organic boron trifluoride salt, wherein the yield is 70-95%.

2. Adding the raw materials and boron trifluoride compound into a solvent under the atmosphere of nitrogen/argon, uniformly mixing, reacting for 6-24 hours at 5-60 ℃, drying the obtained mixed solution under reduced pressure at 20-80 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and reacting to obtain an intermediate; adding an R ⁺ source into a solvent, adding the solvent containing the R ⁺ source into an intermediate, stirring and reacting for 3-24 hours at 5-60 ℃ to obtain a crude product, directly washing the crude product or drying the crude product under reduced pressure, washing, filtering and drying to obtain the final product, namely the unitary organic boron trifluoride salt, wherein the yield is 70-95%.

In the above two specific preparation methods, the boron trifluoride-type compound may include boron trifluoride diethyl etherate, boron trifluoride tetrahydrofuran complex, boron trifluoride butyl etherate, boron trifluoride acetic acid complex, boron trifluoride monoethylamine complex, boron trifluoride phosphoric acid complex, etc. Sources of R ⁺ include metallic lithium/sodium, methanolic lithium/sodium, lithium/sodium hydroxide, ethanolic lithium/sodium, butyllithium/sodium, lithium/sodium acetate, and the like. The solvents described in each place are independently alcohols (some liquid alcohols may also be used as the starting materials at the same time), ethyl acetate, DMF, acetone, hexane, dichloromethane, tetrahydrofuran, ethylene glycol dimethyl ether, and the like. The washing can be performed with small polar solvents such as diethyl ether, n-butyl ether, n-hexane, diphenyl ether, etc.

Example 1

Raw materials

The preparation method comprises the following steps: the starting materials (0.88 g,0.01 mol) and lithium hydroxide (0.24 g,0.01 mol) were mixed homogeneously with 10ml of methanol solution under nitrogen atmosphere and reacted at 15℃for 8 hours. The resulting mixed solution was dried under reduced pressure at 30℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Boron trifluoride diethyl etherate (1.45 g,0.01 mol) and 15ml of THF (tetrahydrofuran) were added to the intermediate, the mixture was stirred at 40℃for 6 hours, and the resulting mixture was dried under reduced pressure at 30℃under a vacuum of about-0.1 MPa, and the crude product obtained was filtered through methylene chloride and dried to give product A1. The yield was 86% and the nuclear magnetism was as shown in FIG. 1.

Example 2

Raw materials

The preparation method comprises the following steps: under nitrogen atmosphere, the raw materials (0.90 g,0.01 mol) and boron trifluoride tetrahydrofuran complex (1.40 g,0.01 mol) were uniformly mixed in 15ml of ethylene glycol dimethyl ether and reacted at room temperature for 10 hours. The resulting mixed solution was dried under reduced pressure at 40℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Lithium ethoxide (0.52 g,0.01 mol) is dissolved in 10ml of ethanol and slowly added into the intermediate, the mixture is stirred and reacted for 8 hours at 45 ℃, the obtained mixture is dried under reduced pressure under the condition of 45 ℃ and the vacuum degree of about-0.1 MPa, and the obtained solid is washed three times by n-butyl ether, filtered and dried to obtain a product A2. The yield was 80% and the nuclear magnetism was shown in FIG. 2.

Example 3

Raw materials

The preparation method comprises the following steps: the starting materials (1.15 g,0.01 mol) and boron trifluoride etherate (1.49 g,0.0105 mol) were mixed homogeneously in 15ml of THF (tetrahydrofuran) under an argon atmosphere and reacted at room temperature for 12 hours. The resulting mixed solution was dried under reduced pressure at 30℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. 6.25ml of a hexane solution of butyllithium (c=1.6 mol/L) was added to the intermediate, the reaction was stirred at room temperature for 7 hours, the obtained mixture was dried under reduced pressure at 30℃under a vacuum of about-0.1 MPa, and the obtained crude product was washed 3 times with cyclohexane, filtered and dried to obtain a product A3. The yield was 89% and the nuclear magnetism was shown in FIG. 3.

Example 4

Raw materials

The preparation method comprises the following steps: under nitrogen atmosphere, a certain amount of raw materials (0.74 g,0.01 mol) and lithium methoxide (0.38 g,0.01 mol) were taken, and mixed uniformly with 20ml of methanol, and reacted at room temperature for 10 hours. The resulting mixed solution was dried under reduced pressure at 40℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Boron trifluoride tetrahydrofuran complex (1.40 g,0.01 mol) and 15ml of THF (tetrahydrofuran) were added to the intermediate, the mixture was stirred at room temperature for reaction for 6 hours, the resulting mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa, and the obtained solid was washed three times with isopropyl ether, filtered and dried to give product A4. Yield 81% and nuclear magnetism as shown in figure 4.

Example 5

Raw materials

The preparation method comprises the following steps: the starting materials (0.91 g,0.01 mol) and lithium hydroxide (0.24 g,0.01 mol) were mixed homogeneously with 10ml of methanol solution under nitrogen atmosphere and reacted at room temperature for 8 hours. The resulting mixed solution was dried under reduced pressure at 40℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Boron trifluoride phosphate complex (1.66 g,0.01 mol) and 15ml of THF were added to the intermediate, stirred at 45℃for reaction for 6 hours, and the resulting mixture was dried under reduced pressure at 60℃under a vacuum of about-0.1 MPa, and the crude product obtained was filtered through methylene chloride and dried to give product A5. The yield was 85% and the nuclear magnetism was shown in FIG. 5.

Example 6

Raw materials

The preparation method comprises the following steps: the raw material (0.88 g,0.01 mol) and boron trifluoride acetic acid complex (1.92 g,0.0102 mol) were uniformly mixed in 15ml of THF (tetrahydrofuran) under an argon atmosphere, and reacted at room temperature for 12 hours, and the resulting mixed solution was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa to remove the solvent, to obtain an intermediate. Lithium acetate (0.68 g,0.0102 mol) was dissolved in 10ml of N, N-dimethylformamide and added to the intermediate, the reaction was stirred at 50℃for 8 hours, the resulting mixture was dried under reduced pressure at 80℃under a vacuum of about-0.1 MPa, and the obtained solid was washed three times with diphenyl ether, filtered and dried to give product A6. The yield was 78% and the nuclear magnetism was shown in FIG. 6.

Example 7

Raw materials

The preparation method comprises the following steps: lithium methoxide (0.38 g,0.01 mol) was dissolved in 15ml of methanol under an argon atmosphere, and after mixing well, the mixture was added to the raw material (1.04 g,0.01 mol) and mixed well, and reacted at 45℃for 12 hours, and the resulting mixed solution was dried under reduced pressure at 45℃and a vacuum of about-0.1 MPa to remove the solvent, to obtain an intermediate. Boron trifluoride diethyl etherate (1.45 g,0.01 mol) and 15ml of THF were added to the intermediate, stirred at room temperature for 24 hours, and the resulting mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa, and the resulting solid was washed three times with methylene chloride, filtered and dried to give product A7. The yield was 75%, and the nuclear magnetism was shown in FIG. 7.

Example 8

Raw materials

The preparation method comprises the following steps: the starting materials (1.04 g,0.01 mol) and lithium hydroxide (0.24 g,0.01 mol) were mixed homogeneously with 10ml of methanol solution under nitrogen atmosphere and reacted at 10℃for 8 hours. The resulting mixed solution was dried under reduced pressure at 40℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Boron trifluoride diethyl etherate (1.45 g,0.01 mol) was added to the intermediate, 10ml of ethylene glycol dimethyl ether solvent was added, stirred at room temperature for 24 hours, the resulting mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa, and the resulting solid was washed three times with methylene chloride, filtered and dried to give product A8. The yield was 82% and the nuclear magnetism was shown in FIG. 8.

Example 9

Raw materials

The preparation method comprises the following steps: the starting materials (1.36 g,0.01 mol) and boron trifluoride etherate (1.45 g,0.01 mol) were mixed homogeneously in 15ml of THF (tetrahydrofuran) under an argon atmosphere and reacted at room temperature for 12 hours. The resulting mixed solution was dried under reduced pressure at 30℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. 6.25ml of a hexane solution of butyllithium (c=1.6 mol/L) was added to the intermediate, the reaction was stirred at room temperature for 6 hours, the obtained mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa, and the obtained crude product was washed 3 times with cyclohexane, filtered and dried to obtain a product A9. The yield was 85% and the nuclear magnetism was shown in FIG. 9.

Example 10

Raw materials

The preparation method comprises the following steps: 10ml of THF was added to the starting material (0.84 g,0.01 mol) under an argon atmosphere, 6.25ml of a hexane solution of butyllithium (c=1.6 mol/L) was slowly dropped into a THF solution of 1-cyclobutene-1-methanol, the reaction was stirred at room temperature for 6 hours, and the resultant mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa to obtain an intermediate. Boron trifluoride diethyl etherate (1.45 g,0.01 mol) and 15ml of THF were added to the intermediate and reacted at room temperature for 12 hours. The resulting mixture was dried under reduced pressure at 30℃and a vacuum of about-0.1 MPa to remove the solvent. The crude product obtained was washed 3 times with cyclohexane, filtered and dried to give product a10. The yield was 85% and the nuclear magnetism was shown in FIG. 10.

Example 11

Raw materials

The preparation method comprises the following steps: the starting materials (1.12 g,0.01 mol) and lithium hydroxide (0.24 g,0.01 mol) were mixed homogeneously with 10ml of methanol solution under nitrogen atmosphere and reacted at 10℃for 8 hours. The resulting mixed solution was dried under reduced pressure at 40℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Boron trifluoride diethyl etherate (1.45 g,0.01 mol) was added to the intermediate, 10ml of ethylene glycol dimethyl ether solvent was added, stirred at room temperature for 24 hours, the resulting mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa, and the resulting solid was washed three times with methylene chloride, filtered and dried to give product A11. The yield was 79% and the nuclear magnetism was shown in FIG. 11.

Example 12

Raw materials

The preparation method comprises the following steps: the starting materials (1.30 g,0.01 mol) and boron trifluoride etherate (1.45 g,0.01 mol) were mixed homogeneously in 15ml of THF (tetrahydrofuran) under an argon atmosphere and reacted at room temperature for 12 hours. The resulting mixed solution was dried under reduced pressure at 30℃and a vacuum of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. 6.25ml of a hexane solution of butyllithium (c=1.6 mol/L) was added to the intermediate, the reaction was stirred at room temperature for 6 hours, the obtained mixture was dried under reduced pressure at 40℃under a vacuum of about-0.1 MPa, and the obtained crude product was washed 3 times with cyclohexane, filtered and dried to obtain product A12. The yield was 83%, and the nuclear magnetism was shown in FIG. 12.

Test example 1

The boron trifluoride organic salt protected by the application mainly plays three roles: 1. the electrolyte is used as an additive in the electrolyte (including liquid and solid), mainly plays a role in generating a passivation layer, and plays a role in supplementing consumed ions because the electrolyte can dissociate ions, so that the first-cycle efficiency, the first-cycle discharge specific capacity, the long-cycle stability and the rate capability of the battery are greatly improved; 2. the electrolyte (including liquid and solid) is used as salt, mainly plays a role in providing ion transmission and passivating electrodes, and is used as salt alone or as double salt in combination with the traditional salt, so that the effect is good; 3. the polymer electrolyte is used as a single ion conductor polymer electrolyte after polymerization and is applied to gel batteries and all-solid-state batteries. The performance of the application is illustrated in the following by way of tests.

1. As an additive in liquid electrolytes

Firstly, in a glove box with the water content less than 10ppm, sequentially adding an organic solvent, salt and conventional additives, and fully and uniformly mixing to prepare the basic liquid electrolytes L1-L10.

The organic solvents used in this test example include methyl ethyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and Ethylene Carbonate (EC), and the conventional additives include fluoroethylene carbonate (FEC), vinylene Carbonate (VC), trimethyl phosphate (TMP), and ethylene sulfate (DTD), and the salts include lithium bis (oxalato) borate (LiBOB), lithium difluoro (liodbb), lithium bis (fluoro) sulfonimide (LiFSI), lithium hexafluorophosphate (LiPF ₆), lithium bis (trifluoromethyl) sulfonimide (LiTFSI), lithium tetrafluoroborate (LiBF ₄), and lithium perchlorate (LiClO ₄). Specifically, the results are shown in Table 1.

Table 1 basic liquid electrolyte formulation

The organic matters A1 to a12 obtained in examples 1 to 12 and the base liquid electrolytes L1 to L10 were thoroughly and uniformly mixed to obtain the series of liquid electrolytes E1 to E15, and specific components, proportions, and the like are shown in table 2.

Table 2 liquid electrolytes E1 to E15 prepared from organic substances of examples 1 to 12

Liquid electrolyte	Basic liquid electrolyte	Additive agent	Additive ratio
				E1	L1	A1	0.5％
E2	L1	A1	1％
				E3	L1	A1	2％
E4	L1	A2	1％
				E5	L2	A3	1％
E6	L3	A4	1％
				E7	L4	A5	1％
E8	L5	A6	1％
				E9	L6	A7	1％
E10	L7	A7	1％
				E11	L8	A8	1％
E12	L9	A9	2％
				E13	L10	A10	1％
E14	L10	A11	1％
				E15	L10	A12	1％

The above-obtained basic liquid electrolytes L1 to L10 and series liquid electrolytes E1 to E15 are assembled into a button cell respectively, concretely as follows: the negative electrode shell, the negative electrode plate, the PE/Al ₂O₃ diaphragm, the electrolyte, the positive electrode plate, the stainless steel sheet, the spring piece and the positive electrode shell are assembled into a button cell, and long-cycle test is carried out at room temperature, wherein the cycle mode is 0.1C/0.1C1 week, 0.2C/0.2C5 week and 1C/1C44 week (C represents multiplying power), the positive electrode plate is a wafer with the diameter of 12mm, the negative electrode plate is a wafer with the diameter of 14mm, the diaphragm is a wafer with the diameter of 16.2mm, and the diaphragm is a commercial Al ₂O₃/PE porous diaphragm, and the specific examples are shown in tables 4 and 5.

Wherein, the preparation process of the positive electrode plate and the negative electrode plate of the battery is as follows:

(1) Positive electrode plate

Adding an active material of a positive electrode main material, a conductive additive and a binder into a solvent according to a ratio of 95:2:3, wherein the solvent accounts for 68% of the total slurry, and uniformly mixing and stirring to obtain positive electrode slurry with certain fluidity; and coating the anode slurry on an aluminum foil, and drying and compacting to obtain the usable anode plate. Here, lithium cobaltate (LiCoO ₂, abbreviated LCO), lithium nickel cobalt manganate (NCM 811), lithium nickel cobalt aluminate (LiNi _0.8Co_0.15Al_0.05O₂, abbreviated NCA), lithium nickel manganate (LiNi _0.5Mn_1.5O₄, abbreviated LNMO), carbon Nanotubes (CNT) and SuperP were used as the conductive additive, polyvinylidene fluoride (PVDF) was used as the binder, and N-methylpyrrolidone (NMP) was used as the solvent.

(2) Negative pole piece

Adding a negative electrode main material active substance (except metal lithium), a conductive additive and a binder into solvent deionized water according to a ratio of 95:2:3, wherein the solvent accounts for 45% of the total slurry, and uniformly mixing and stirring to obtain negative electrode slurry with certain fluidity; and coating the negative electrode slurry on a copper foil, and drying and compacting to obtain the usable negative electrode plate. The active materials are graphite (C), silicon oxygen carbon (SiOC 450), lithium metal (Li), carbon Nanotubes (CNT) and SuperP as conductive agents, and carboxymethylcellulose (CMC) and Styrene Butadiene Rubber (SBR) as binders.

The positive and negative electrode systems selected are shown in Table 3:

TABLE 3 Positive and negative electrode systems

Positive and negative electrode system of battery	Positive electrode material	Negative electrode material
			X1	LCO	SiOC450
X2	NCM811	SiOC450
			X3	NCA	C
X4	NCM811	Li
			X5	LNMO	C

The batteries 1 to 16 and the comparative batteries 1 to 12 were tested for initial cycle efficiency, initial cycle discharge specific capacity, and cycle 50 cycle capacity retention at room temperature, the configuration and test patterns of the examples and comparative batteries are shown in table 4, and the test results are shown in table 5.

Table 4 examples and comparative examples battery configurations and test patterns

TABLE 5 comparison of test results of first week efficiency, first week discharge specific Capacity and cycle 50 week Capacity Retention Rate

It can be seen that the battery added with the material provided by the application as an additive has higher first-week discharge specific capacity, higher first-week efficiency, higher capacity retention rate after 50 weeks circulation and better performance than the current conventional additive compared with the comparative battery which is not added. In addition, cells using boron-containing salt additives exhibit more excellent electrochemical performance in the presence of conventional additives.

2. As salt in liquid electrolytes

(1) Preparing liquid electrolyte

A1, A5, A6, A7 and A12 are uniformly mixed with an organic solvent, a conventional additive and conventional salt to obtain series of liquid electrolytes R1, R5, R6, R7 and R12, the conventional salt, the organic solvent and the conventional additive are uniformly mixed to obtain series of conventional liquid electrolytes Q1, Q5, Q6, Q7 and Q12, and the used solvent and the conventional additive both comprise the solvent and the conventional additive described in the test example I. Specific components, proportions, and the like of the liquid electrolyte are shown in table 6.

Table 6 liquid electrolyte formulated with boron-containing organics synthesized as salts

Note that: 1M means 1mol/L.

(2) Battery assembly

The obtained series of liquid electrolytes R (shown in table 6) and the conventional liquid electrolytes Q (shown in table 6) were assembled into button cells, and the positive and negative electrodes, the separator size, the assembly method, and the cycle mode of the cells were the same as those of the button cells shown in the test example "one", namely, the cells (i.e., examples) 1, 5,6, 7, 12 and the corresponding comparative cells, respectively. The specific configuration, cycle mode and voltage ranges of the cells are shown in table 7, and the first-week discharge specific capacity, first-week efficiency and cycle 50-week capacity retention results of the cells (i.e., examples in table 7 or 8) and the comparative cells (i.e., comparative examples in table 7 or 8) at room temperature are shown in table 8.

Table 7 examples and comparative examples button cell configuration and test mode

Table 8 comparative examples and comparative examples comparative button cell test results shown in table 7

In summary, the boron trifluoride salt provided by the invention is independently used as salt for transmitting ions or forms double salts with conventional salt in a nonaqueous solvent, the ions are easy to solvate, higher ionic conductivity is provided for a battery, the stability is high, the boron trifluoride salt has better comprehensive performance, and in a liquid battery system with LCO and NCM811 as positive electrodes and SiOC450 and Li as negative electrodes, the boron trifluoride salt has very excellent electrochemical performance, and the first-week efficiency, the first-week specific discharge capacity and the capacity retention rate are higher, and the performance of the boron trifluoride salt is equal to or slightly better than that of a battery corresponding to the conventional salt.

3. Single ion conductor polymer electrolyte

(1) Preparing electrolyte

The monomers (compounds A1, A2, A4, A5, A9, a10, a11, a12 in the examples of the present application), the plasticizer, the battery additive, the salt, and the initiator were uniformly stirred to form a precursor solution, and the precursors S1, S2, S4, S5, S9, S10, S11, S12 were obtained, with the specific formulation shown in table 9. The initiator used was Azobisisobutyronitrile (AIBN), benzoyl Peroxide (BPO), stannous isooctanoate (Sn (Oct) ₂).

TABLE 9 precursor solution composition

(2) Battery assembly

Electrolyte precursor solutions S1, S2, S4, S5, S9, S10, S11, S12 obtained from table 9, from which the respective soft-pack batteries, i.e., batteries 1,2, 4,5, 9, 10, 11, 12 were assembled; the method comprises the following steps: the positive electrode plate with the size of 64mm multiplied by 45mm, the negative electrode plate with the size of 65mm multiplied by 46mm and the diaphragm are assembled into a 2Ah soft package battery core, and the secondary batteries are obtained through lamination, baking, liquid injection and formation processes, wherein the battery assembling system is X2 in the table 3, and the diaphragm uses a commercial PE/Al ₂O₃ porous membrane.

(3) Battery testing

After the secondary batteries prepared by the electrolyte precursor solutions S1, S2, S4, S5, S9, S10, S11 and S12 are completely cured in situ, the first-week discharge capacity, the first-week efficiency and the cycling capacity retention rate of the batteries are tested at room temperature, the test voltage ranges from 3.0V to 4.2V, wherein the cycling mode is 0.1C/0.1C2 week and 0.3C/0.3C48 week (C represents multiplying power), and the test results are shown in Table 10.

Table 10 test results of the battery of the example

Battery cell	First week discharge capacity (Ah)	First week efficiency (%)	Cycle 50 week Capacity retention (%)
				Battery 1	1.74	86.8	79.6
Battery 2	1.90	94.6	89.8
				Battery 4	1.94	96.5	90.3
Battery 5	1.92	95.8	90.1
				Battery 9	1.88	93.3	89.9
Battery 10	1.73	86.0	79.1
				Battery 11	1.76	87.4	80.0
Battery 12	1.89	94.2	90.4

As shown in table 10, it was found from the test data in examples that the precursor solutions composed of the polymerizable monomers A1, A2, A4, A5, A9, a10, a11, a12 were cured in situ and then used as polymer electrolytes, and that the solid-state battery system of NCM811/SiOC450 exhibited very excellent electrochemical properties, and the first-week efficiency, first-week discharge capacity, and capacity retention were all relatively high. From examples 1, 10, and 11 (as shown in Table 10, no conventional salt was added to the system), solid electrolytes excellent in performance were obtained after polymerization; when used in additional matching with conventional salts, the cells exhibit more excellent electrochemical performance due to the increased number of dissociated ions.

In addition, the present application also shows the effect patterns of some examples as additives, salts and polymer electrolytes. FIGS. 13 to 16 are graphs showing the effect of the cells 1/6/9/14 prepared from examples 1/6/9/14 as liquid electrolyte additives, respectively, compared with the corresponding comparative cells 1/4/7/11 not containing the examples of the present application. FIGS. 17 to 18 are graphs showing the effect of the battery 1/7 prepared as a liquid electrolyte salt according to example 1/7 and the corresponding comparative battery 1/7 not containing the example of the present application, respectively. Fig. 19 is an effect diagram of the polymer electrolyte battery 2 produced by polymerizing the monomer in example 2; fig. 20 is an effect diagram of the polymer electrolyte battery 10 produced by polymerizing the monomer in example 10.

In summary, the performances such as the first cycle efficiency, the first cycle discharge specific capacity, the first cycle discharge capacity, the capacity retention rate and the like have direct and remarkable influence on the overall performance of the battery, and directly determine whether the battery can be applied. Thus, improving these properties is a goal or direction for many researchers in the field, but in the field, improvement of these properties is very difficult, and generally improvement of about 3-5% is a major advance. The present application has surprisingly found that these data are greatly improved over conventional data in earlier experimental data. When the electrolyte is used as a liquid electrolyte additive, the battery performance is improved by about 5-35%, and the additive provided by the application has a better effect when being used in combination with a conventional additive; the material provided by the application has very good salt effect as electrolyte, has better effect when being matched with conventional salt, can also use higher concentration (such as 1.5M and 2M) to obtain high-salt system electrolyte, and has very outstanding effect on electrochemical performance of a battery, and is not repeated here; the material provided by the application can also initiate polymerization to form single-ion conductor polymer electrolyte, and is applied to gel batteries, quasi-solid batteries and all-solid batteries. The structure type of the application is also greatly different from the conventional structure, so that a new direction and thought are provided for the research and development in the field, a large space is also provided for the further research, and the substance in the application can be used for multiple purposes in one structure; the meaning is extremely great.

Test example 2

The test example is provided with test groups 1-3 and control groups 1-3. Wherein, test group 1 employed the electrolyte provided in example 1 above, test group 2 employed the electrolyte provided in example 2 above, and test group 3 employed the electrolyte provided in example 3 above.

The control group 1 used an electrolyte of the structure shown below:

the control group 2 used an electrolyte having the following structure:

the control group 3 used an electrolyte having the following structure:

The batteries of the test groups 1-3 and the control groups 1-3 were prepared by the following methods:

(1) Preparation of a positive plate: positive electrode active material, conductive agent acetylene black, binder polyvinylidene fluoride (PVDF) according to 80:10:10, adding a certain amount of solvent N-methyl-2-pyrrolidone (NMP), fully grinding for 1 hour in a mixer, then coating a film with a certain thickness on a current collector aluminum foil through an automatic coating machine, placing in an 80 ℃ blast drying box for drying for 30 minutes, and placing in a 120 ℃ vacuum drying box for drying for 12 hours. And rolling the dried pole piece by a pair roller machine to tightly combine the active substance with the current collector. Cutting the pressed pole piece into a round piece with the diameter of 12mm, then carrying out vacuum drying again, and storing for later use.

(2) Preparation of a negative plate, a liquid electrolyte and a diaphragm: the negative pole piece adopts a lithium metal sheet with the thickness of 1.5mm and the diameter of 14 mm; the liquid electrolyte is prepared by dissolving each group of electrolyte in a solution of EC: DEC: EMC=1:1:1 (volume ratio) (the solid content of each group of electrolyte is 20%) and adding 1% of AIBN or Sn (Oct) ₂ initiator; the membrane was a commercial Al ₂O₃/PE porous membrane, which was cut by a microtome into discs of Φ16mm.

(3) Assembling a battery: and (3) assembling the battery in a glove box filled with argon, wherein the oxygen content and the water content in the glove box are lower than 1ppm, and after the dried positive and negative electrode plates are moved into the glove box, assembling the negative electrode shell, the negative electrode plate, the PE/Al ₂O₃ diaphragm, the liquid electrolyte, the positive electrode plate, the stainless steel sheet, the spring piece and the positive electrode shell into a button battery in sequence, and sealing by a sealing machine. The coin cell was then heated in an oven at 60 ℃ for 12 hours. The battery assembly system was X4 in table 3 and the separator used a commercial PE/Al ₂O₃ porous membrane. The first week discharge specific capacity, first week efficiency, and cycle 50 week capacity retention of the batteries of test group 1-3 and control group 1-3 were respectively tested and recorded, and the results are shown in table 11.

Table 11 comparison of test results of test and control batteries

It can be seen that the first week discharge specific capacity, the first week efficiency and the 50 week capacity retention rate of the control group 1-3 were all lower than those of the test group 1-3, probably because the relative amount of lithium ions in the control group 1 was lower and the transmission of lithium ions was worse when the electrolyte solid contents were the same; the monomer of control group 2 was slightly less stable to Li although it was free radically polymerizable; the control group 3 is a small molecule which can not be polymerized, and a stable passivation protection layer can not be formed on the surface of the metal lithium, so that the side reaction between the metal lithium and the electrolyte can not be prevented, the viscosity is slightly high, and the ion transmission performance is slightly low. In conclusion, the electrolyte provided by the application can effectively improve the battery performance, prolong the service life of the battery and improve the safety of the battery through in-situ polymerization in the battery.

In the present application, the structures in examples 1 to 12 were selected as representative to illustrate the production method and effect of the present application. Other structures not listed can be prepared using the methods described in any of examples 1-12. The preparation method comprises the steps of reacting raw materials, boron trifluoride compound and R ⁺ source to obtain the product boron trifluoride organic salt, namely that the-OH in the raw materials is changed intoR ⁺ can be Li ⁺、Na⁺ or the like, and other structures are unchanged. In addition, many of the structure the inventor's research team has made series effect tests, which are very good, similar to those of the above embodiment, but only some of the structure is described due to the space relation.

In the present application, only a part of the structures are selected as a representative in the examples to illustrate the production method, effect, etc. of the present application, and other structures not listed have similar effects. For example:

Etc.

The raw materials used in the examples can be purchased or simply prepared, and the preparation process is also known in the art, so they are not described in detail in the specification.

It should be noted that the present inventors have made a great number of experiments on the series of structures, and sometimes, for better comparison with the existing system, there are cases where the same structure and system are used for more than one experiment, and thus, there may be some errors in different experiments.

Finally, it should be noted that: the embodiments described above are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced with equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims

1. A polymerizable electrolyte, characterized in that the electrolyte comprises a boron trifluoride salt,

The boron trifluoride salt is selected from:

At least one of .

2. A method for preparing a polymerizable electrolyte according to claim 1, characterized in that the method is to obtain a product by reacting a monovalent structure containing a -OH, a boron trifluoride compound and an R ⁺ source, that is, a monovalent structure containing a -OH, a boron trifluoride compound and an R + source. The structure of the boron trifluoride salt, where R ⁺ is a lithium ion.

3. An application of the polymerizable electrolyte according to claim 1 in a secondary battery, characterized in that the application is: the boron trifluoride salt is used as an additive to the electrolyte, or as a salt, or as a single ion conductor and polymer framework after polymerization of a monomer containing a polymerizable group.

4. The application according to claim 3 is characterized in that the application includes application in liquid electrolyte, gel electrolyte, mixed solid-liquid electrolyte, quasi-solid electrolyte, and all-solid electrolyte, and the liquid electrolyte, gel electrolyte, mixed solid-liquid electrolyte, quasi-solid electrolyte, and all-solid electrolyte independently include the electrolyte according to claim 1.

5. The application according to claim 4, wherein the application also includes application as a battery or a battery pack, wherein the battery comprises the electrolyte according to claim 1 and a positive electrode, a negative electrode and a packaging shell; the liquid electrolyte, gel electrolyte, mixed solid-liquid electrolyte, quasi-solid electrolyte, and all-solid-state electrolyte are applied to liquid batteries, gel batteries, mixed solid-liquid batteries, quasi-solid-state batteries and all-solid-state batteries, and the battery pack comprises the battery.