CN114605448A

CN114605448A - Electrolyte containing unsaturated heterochain structure and preparation method and application thereof

Info

Publication number: CN114605448A
Application number: CN202011422438.0A
Authority: CN
Inventors: 俞会根; 杨萌; 程勇斌
Original assignee: Beijing WeLion New Energy Technology Co ltd
Current assignee: Beijing WeLion New Energy Technology Co ltd
Priority date: 2020-12-08
Filing date: 2020-12-08
Publication date: 2022-06-10

Abstract

The application provides an electrolyte containing an unsaturated heterochain structure, and a preparation method and application thereof. The electrolyte comprises boron trifluoride salt, and the structure of the boron trifluoride salt is shown as a general formula I. When the boron trifluoride salt provided by the application is used as an additive of an electrolyte, a stable passivation layer is formed on the surface of an electrode, so that the first effect and the cycle performance of a battery can be obviously improved; when the salt is used as a salt in an electrolyte, the salt has better ion transmission and stable electrochemical performance; the monomer with the polymerizable group can also be used as a single ion conductor and a macromolecular framework after in-situ/ex-situ polymerization, and has good effect. The boron trifluoride salt provided by the application can be applied to liquid batteries, solid-liquid hybrid batteries, semi-solid batteries, gel batteries, quasi-solid batteries and all-solid batteries, and is beneficial to improvementHigh energy density, high cycle stability and long service life. And the raw materials are low in price, the synthesis process is simple, and the method has good economic benefit. MF (MF)₃BS‑R₁-R is of the general formula I.

Description

Electrolyte containing unsaturated heterochain structure and preparation method and application thereof

Technical Field

The application relates to the technical field of batteries, in particular to an electrolyte containing an unsaturated heterochain structure and a preparation method and application thereof.

Background

The secondary battery has the characteristics of high energy density, low self-discharge, no memory effect and high power, is widely applied to various fields, gradually expands from small-capacity battery application products such as consumer electronics products and electric tools to emerging fields such as new energy electric vehicles, electric airplanes, electric ships and robots, further expands the requirements of the application fields on the capacity and the energy density of the battery, and continuously improves the requirements on battery materials.

In order to increase the energy density of a lithium battery, for example, a high-voltage high-specific-volume positive electrode material and a low-voltage high-capacity negative electrode material, such as a high-voltage Lithium Cobaltate (LCO), a high-nickel ternary (NCM811, NCM622, NCM532, and NCA), or a Lithium Nickel Manganese Oxide (LNMO), and a negative electrode material such as metallic lithium, graphite, or silicon oxycarbon, are used. While matching the electrolyte with a wide electrochemical window or forming a stable passivation layer on the surface of the electrode to improve the cycling stability of the battery.

Since the solid electrolyte can greatly improve the safety of the battery, the solid battery is developed in many countries in recent years, but the solid battery itself has great disadvantages, such as: the polymer electrolyte has low ionic conductivity and relatively large interface impedance with the electrode; the oxide electrolyte is hard and brittle, is not easy to process and has large interface impedance with the electrode; the sulfide electrolyte is extremely sensitive to air, and a space charge layer exists between the sulfide electrolyte and a conventional oxide anode, so that the compatibility is poor. Therefore, the market is mainly liquid batteries, and the liquid electrolyte has the remarkable advantages of high conductivity and good wettability to the inside of the electrode. The battery can consume partial ions extracted from the positive electrode in the first period, and a passivation layer which only conducts ions and does not conduct electrons is formed on the surfaces of the positive electrode particles and the negative electrode particles. The formed passivation layer has a protection effect on the positive and negative electrodes, so that the positive and negative electrodes and the liquid electrolyte are more stable, and the electrochemical properties of the battery, such as charge and discharge, storage, cycle life and the like, are determined. If the formed passivation layer is unstable, the passivation layer is continuously damaged and formed along with the increase of the cycle number, so that active ions in the electrode are continuously consumed, the first-cycle discharge capacity of the battery is low, the capacity attenuation is serious, and the battery rapidly fails. In order to improve the stability of the battery during cycling, film-forming additives, such as organic film-forming additives FEC (fluoroethylene carbonate), VC (vinylene carbonate), VEC (ethylene vinylene carbonate), PS (propylene sulfite), and 1,3-PS (1, 3-propane sultone), etc., are generally added to the common liquid electrolyte. Wherein the SEI passive film formed on the surface of the negative electrode contains various inorganic components Li as main component₂CO₃、LiF、Li₂O, LiOH, and various organic components ROCOOLi, ROLi, ROCOOLi, and conventional organic film-forming electrolyte additives contain no dissociable ions, and only consume positive ions to form a surface passivation layer, so the first-effect and specific discharge ratios are low. If the added additive can form a passivation layer with good ion conduction and stability on the surface of the electrode and consume less ions from the electrode, the liquid electrolyte and the polymer electrolyte with narrow electrochemical windows can be applied to a high-voltage battery system, and the energy density and the cycle life of the battery can be greatly improved. In addition, the salt synthesis/purification process of the current commercial electrolyte is complex and has high price, so that the cost of the whole battery is higher, and if the salt synthesis/purification process of a new electrolyte is simple and has low price, the salt synthesis/purification process can partially or completely replace the salt of the electrolyte in the prior art, so that the excellent performance and the lower cost can be both considered.

[-SBF₃]^-Is a strongly polar group capable of forming a salt with a cation, thus, -SBF₃M has a strong sense of existence in a molecular structure, and its addition may change the properties of the entire molecular structure. In the prior art, only very few researchers have been working on BF-containing formulations₃The compounds of the group were studied sporadically.

Patent No. CN105789701A discloses an electrolyte additive comprising a hydrogenated thiophene-boron trifluoride complex compound and lithium fluorophosphate, wherein the hydrogenated thiophene-boron trifluoride complex compound is at least one selected from compounds having a structural formula shown in formula (1): wherein R is₁，R₂，R₃，R₄Each independently selected from hydrogen, halogen, cyano, substituted orUnsubstituted C1-20 alkyl, substituted or unsubstituted C2-20 alkenyl, substituted or unsubstituted C6-26 aryl; the substituent is selected from halogen and cyano. However, the compound is a complex compound, is not a sulfenyl salt, and has no great research result at present and no industrial application result.

The applicant has surprisingly found that Li is contained⁺/Na⁺Of (2) SBF₃M salt has a good effect in batteries, and therefore, a special formation team carries out a special study on the battery containing-SBF₃M salt and achieves better research results.

The present application is directed to-SBF₃The structure of M linked to an unsaturated heterochain to which-SBF is linked is independently studied₃M, an effect different from that of other structures may be produced. The subject of the present application is therefore identified as a direct or indirect linkage of-S-BF to an unsaturated heterochain₃M, thereby more specifically determining-S-BF₃The specific case where M is attached to an unsaturated heterochain.

Disclosure of Invention

In view of this, embodiments of the present application provide an electrolyte containing an unsaturated heterochain structure, and a preparation method and an application thereof, so as to solve technical defects in the prior art.

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

MF₃BS-R₁-R is of the general formula I

Wherein M is a metal cation; r is independently a first chain containing no or at least one atom; r₁Independently a second chain free or containing at least one atom; h on any one C of the first and second chains may be independently substituted with a substituent group including H, a chain substituent group containing at least one atom, and a cyclic substituent group; the first isThe chain, second chain and chain substituents contain at least one heteroatom other than carbon and at least one unsaturated bond, including double or triple bonds.

Further, in the general formula I, the hetero atom includes a halogen atom, S, N, O, P, Se, Ca, Al, B or Si;

the unsaturated bond includes at least one of C ≡ C, C ≡ C, C ≡ N, C ≡ N, C ≡ O, P ═ O, S ═ O and N ≡ O.

Further, in the general formula I, R is an unsaturated heterochain of 1 to 20 atoms; r₁Is an unsaturated heterochain of 0 to 5 atoms; the hetero atom includes a halogen atom, S, N, O, P, Ca, B or Si.

Further, the chain substituent is selected from the group consisting of a halogen atom, an etheroxy group, an etherthio group, a nitro group, a cyano group, a carbonyl group, an ester group, an aldehyde group, a disubstituted amino group, a sulfoalkane, an amide, a sulfonamide group, a sulfo group, an alkyl group, a heteroalkyl group, an alkenyl group, a heteroalkenyl group, an alkynyl group, a heteroalkynyl group, an alkenylalkynyl group, an O group, an S group, an O group, a n group, an O group, a n group, a n, a,

＝N-R₄A salt substituent and a substituent in which H on any one of C of these substituents is substituted by halogen;

the cyclic substituent comprises a three-membered ring, a four-membered ring, a five-membered ring, a six-membered ring, a seven-membered ring, an eight-membered ring and a polycyclic substituent containing two or more ring structures; the cyclic substituent can be connected with a first substituent selectively;

wherein the ester group comprises carboxylate, carbonate, sulfonate and phosphate, and the heteroatoms in the heteroalkyl, heteroalkenyl and heteroalkynyl groups are selected from the heteroatoms described in any of the preceding paragraphs; r₂、R₃And R₄Independently H, alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl and alkenynyl, preferably R₄In a non-H configuration, the salt substituents include, but are not limited to, sulfate, sulfonate, sulfonimide, carbonate, carboxylate, thioether, oxoether, ammonium, hydrochloride, nitrate, azide, silicateAnd a phosphate.

Further, the general formula I includes the following structure:

(A)

(B)

(C)

(D)

in the above-mentioned (A), (B), (C) and (D), Q represents-SBF₃M or-R₁-SBF₃M；A₁-A₂₉Independently selected from the group defined for the substituents described in any one of the preceding paragraphs, preferably said substituents are selected from H, C₁-C₆Alkyl or said cyclic substituent;

and in (B), at least one of each structureThe substituent Z is a group containing ═ O, -N ═ O, ═ S, ═ N-R₄-P ═ O, nitro, ester, cyano, heteroalkenyl, heteroalkynyl, aldehyde, amide, sulfonamide, or sulfo; in (C), at least one substituent Z in each structure is a substituent containing an unsaturated bond; in (D), at least one substituent Z in each structure is a substituent containing a heteroatom selected from the heteroatoms as defined in any one of the above paragraphs.

Further, in (A) to (D), A in each structure₁-A₂₉Each independently is a second substituent selected from the group consisting of H, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, a vinyl group, a propenyl group, an ethynyl group, a propynyl group, a disubstituted amino group, a nitro group, a cyano group, an ester group, an aldehyde group, a sulfoalkane, an amide, a sulfonamide group, a sulfo group, an O, an S, an O, an aldehyde, a compound, a salt,

＝N-R₄a cyclic substituent or a group obtained by substituting H on any one C of the second substituent by halogen; r, R₁Independently selected from methyl, ethyl, propyl, isopropyl, butyl, isobutyl or halogenated groups formed by substituting H on any one C of the groups by halogen; a first substituent is optionally connected to the cyclic substituent; the first substituent being of the type defined for said substituent;

and in (B), at least one substituent Z in each structure is ═ O, ═ S, ═ N-R₄Nitro, ester, cyano, aldehyde; in (C), at least one substituent Z in each structure is ═ O, ═ S, ═ N-R₄Vinyl, propenyl, ethynyl, propynyl, nitro, ester, cyano, aldehyde; in (D), at least one substituent Z in each structure is ═ O, ═ S, ═ N-R₄Halogen atom, alkoxy, alkylthio, nitro, ester group, cyano, aldehyde group;

preferably, R₂、R₃Independently is H, methyl, ethyl, a halogen atom, R₄Is methyl or ethyl.

Further, in (a) to (D), the second substituent is selected from H, a halogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a methoxy group, an ethoxy group, an ethenyl group, a propenyl group, an ethynyl group, an ═ O group, a phenyl group, or a group in which H of any one C of the second substituents is substituted with a halogen; the first substituent is selected from H, alkyl, halogen atom, nitro, aldehyde group, halogenated alkyl, alkenyl, alkynyl, ester group, carbonyl, ═ O, ═ S, ═ CH₂Alkylthio, cyano, sulfonyl or alkoxy; and in (B), at least one substituent Z in each structure is ═ O, cyano, aldehyde; in (C), at least one substituent Z in each structure is ═ O, vinyl, ethynyl; in (D), at least one substituent Z in each structure is ═ O, a halogen atom, or an alkoxy group;

and preferably the second substituent Z attached to the last carbon atom is H, a halogen atom, methyl, -CF₃、-CHF₂、-CH₂F; the substituent Z attached to Si is not H.

Further, M in the general formula I comprises Na⁺、K⁺、Li⁺、Mg²⁺Or Ca²⁺Preferably Na⁺、K⁺Or Li⁺；

All or part of the hydrogen atoms on all carbon atoms in any one general formula I are independently replaced by halogen atoms; preferably, all or part of the hydrogen atoms on all carbon atoms in any one of the general formula I are independently substituted by fluorine atoms;

all or part of the oxygen atoms in any one of the general formulae I are independently substituted by sulfur atoms.

The application also provides a preparation method of the electrolyte containing the unsaturated heterochain structure, and the electrolyte is obtained by reacting the sulfydryl, the boron trifluoride compound and the M source.

The present application also provides an application of an electrolyte containing an unsaturated heterochain structure in a secondary battery, the application being: the boron trifluoride salts can be used both as salts and as additives; the polymerizable monomer in the general formula I can be polymerized and then used as a single-ion conductor and polymer framework;

preferably, the application includes application in liquid electrolyte, gel electrolyte, mixed solid-liquid electrolyte, quasi-solid electrolyte and all-solid electrolyte, which independently include the electrolyte containing unsaturated heterochain structure described in any paragraph above;

preferably, the application also includes the application as a battery or a battery pack, the battery comprises the electrolyte containing the unsaturated heterochain structure, a positive electrode, a negative electrode and a packaging shell, and the liquid electrolyte, the gel electrolyte, the mixed solid-liquid electrolyte, the quasi-solid electrolyte and the all-solid electrolyte can 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 includes the battery.

The technical effects are as follows:

the boron-containing organic compound 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 direct contact between an electrolyte and an electrode active substance, inhibits decomposition of each component of the electrolyte, widens an electrochemical window of a whole electrolyte system, and can remarkably improve the discharge specific capacity, the coulombic efficiency and the cycle performance of the battery; in addition, the boron-containing organic compound is an ionic conductor and is used as an additive, a passivation layer is formed on the surface of an electrode, active ions coming out of the positive electrode are less consumed, and the first coulombic efficiency and the first cycle discharge specific capacity of the battery can be obviously improved. And when the electrolyte containing the boron 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 a battery, the electrochemical performance of the battery is improved. In addition, the structure of the application can be mixed with conventional additives for use, namely, a double additive or a multi-additive, and the battery using the double additive or the multi-additive shows more excellent electrochemical performance.

The boron-containing organic compound provided by the application can also be used as a main salt of an electrolyte, and can be used as the main salt alone or used as a double salt or a multiple salt together with other conventional salts. The structure contains ions which are easy to be dissociated, so that high ionic conductivity can be provided, the stability is high, and the current collector is not corroded, so that the assembled battery has excellent electrochemical performance.

The boron-containing organic compounds provided by the present application, if containing polymerizable groups, can also be applied as single-ion conductors and polymer frameworks after in-situ/ex-situ polymerization. If the ionic conductivity of the ionic liquid is matched with that of the conventional salt for use, the ionic conductivity is higher, and the effect is better.

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

In addition, the metal such as sodium, potassium and the like except for the traditional lithium can be used for forming salt, so that more possibilities are provided for later application, cost control or raw material selection, and the like, and the significance is great.

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

Drawings

FIGS. 1-2 are nuclear magnetic hydrogen spectra of the products of examples 5-6 of the present application; FIGS. 3-4 are nuclear magnetic hydrogen spectra of the products of examples 9-10 of the present application; FIGS. 5-6 are nuclear magnetic hydrogen spectra of the products of examples 14-15 of the present application;

FIGS. 7-10 are graphs comparing the performance of battery 6/9/11/12 made with example 6/9/11/12 as an electrolyte additive to a corresponding comparative battery 6/9/11/12 that did not contain example 6/9/11/12 of the present invention;

FIGS. 11-12 are graphs comparing the effect of a battery 6/10 made from example 6/10 as a liquid electrolyte salt with a corresponding comparative battery 6/10 that did not contain example 6/10 of the present invention;

FIG. 13 is a graph comparing the effect of example 15 made as a cell 15 with salt in solid electrolyte with a comparative cell 2 made with LiTFSI as the salt;

FIG. 14 is a graph showing the effects of the monomer of example 3 polymerized to form a battery 3 as a polymer electrolyte.

Detailed Description

The following description of specific embodiments of the present application refers to the accompanying drawings.

In the present invention, unless otherwise specified, scientific and technical terms used herein have the meanings that are commonly understood by those skilled in the art. Also, the reagents, materials and procedures used herein are those that are widely used in the corresponding fields. Meanwhile, in order to better understand the present invention, the definitions and explanations of related terms are provided below.

By "a chain of xx atoms in length" or similar expression is meant that the longest chain is xx atoms, e.g. if a chain of 3 atoms in length is formed, the number of atoms making up the chain is 3, and no H or substituents thereon are counted, e.g. CH₃-CH(CH₃)-CH₃Is a chain of 3 atoms length, CH₃-O-CH₃Also a 3 atom long chain.

In the title and description of the invention, -SBF₃M in M may be a monovalent, divalent, trivalent or polyvalent metal cation, if it is a non-monovalent ion, then-SBF₃The number of (c) is increased correspondingly so that it exactly matches the valence of M.

The "boron trifluoride-based compound" refers to boron trifluoride, a compound containing boron trifluoride, a boron trifluoride complex or the like.

In the present invention, if a substituent Z is attached to a certain atom in the chain₀Then represents and Z₀Any H on the attached atoms may be independently substituted by a substituent Z₀Substituted, if there are more than one H, then Z₀Can replace one H or replace two or more H, and the stituents can be same or different; for example, the structure is

Wherein Z₀Is selected from the group consisting of substituents of ═ O, methyl, F and the like, then it may be

And the like.

The invention provides a monobasic organic boron trifluoride salt which can be used as an electrolyte additive, an electrolyte salt and a polymerizable monomer, namely, the organic compound contains-SBF₃M is a group in which M is Li⁺、Na⁺And 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, the boron trifluoride compound is obtained by reacting a raw material, a boron trifluoride compound and an M source, specifically, -SH in the raw material participates in the reaction, and other structures do not participate in the reaction. The specific preparation method mainly comprises two methods:

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

Secondly, under the atmosphere of nitrogen/argon, adding the raw materials and boron trifluoride compounds into a solvent, uniformly mixing, reacting for 6-24 hours at the temperature of 5-60 ℃, decompressing and drying the obtained mixed solution at the temperature of 20-80 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and reacting to obtain an intermediate; adding an M source into a solvent, then adding the solvent containing the M 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 washing the crude product after drying under reduced pressure, then filtering and drying to obtain a final product, namely, the monobasic organic boron trifluoride salt, wherein the yield is 70-95%.

In the above two specific preparation methods, the boron trifluoride compounds may include boron trifluoride diethyl etherate complex, boron trifluoride tetrahydrofuran complex, boron trifluoride dibutyl etherate complex, boron trifluoride acetic acid complex, boron trifluoride monoethyl amine complex, boron trifluoride phosphoric acid complex, and the like. M sources include lithium/sodium metal tablets, lithium/sodium methoxide, lithium/sodium hydroxide, lithium/sodium ethoxide, butyl lithium/sodium, lithium/sodium acetate, and the like. The solvent is independently alcohol (some liquid alcohol can be used as solvent), ethyl acetate, DMF, acetone, hexane, dichloromethane, tetrahydrofuran, ethylene glycol dimethyl ether, etc. The washing can be carried out with a small polar solvent such as diethyl ether, n-butyl ether, n-hexane, diphenyl ether, etc.

Example 1

Raw materials

The preparation method comprises the following steps: the raw material (0.01mol) and boron trifluoride tetrahydrofuran complex (1.4g,0.01mol) were mixed uniformly in 15ml of ethylene glycol dimethyl ether under a nitrogen atmosphere, and reacted at room temperature for 12 hours. The obtained mixed solution is decompressed and dried at 40 ℃ and under the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. Dissolving lithium ethoxide (0.52g, 0.01mol) in 10ml ethanol, slowly adding the solution into the intermediate, stirring and reacting for 8 hours at 45 ℃, drying the obtained mixed solution under reduced pressure at 45 ℃ and under the vacuum degree of about-0.1 MPa, washing the obtained solid with n-butyl ether for three times, and filtering and drying to obtain a product P1. The yield of product P1 was 85%.

Example 2

Raw materials

The preparation method comprises the following steps: the starting material (0.01mol) and boron trifluoride diethyl etherate (1.42g,0.01mol) were mixed uniformly in 15ml of THF (tetrahydrofuran) under an argon atmosphere, and reacted at room temperature for 12 hours. The obtained mixed solution is decompressed and dried at 30 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. 6.30ml of butyllithium in hexane (c 1.6mol/L) was added to the intermediate, the reaction was stirred at room temperature for 10 hours, the resulting mixture was dried under reduced pressure at 40 ℃ under a vacuum degree of about-0.1 MPa, and the resulting crude product was washed with cyclohexane 3 times, filtered and dried to obtain product P2. The yield of product P2 was 87%.

Example 3

Raw materials

The preparation method comprises the following steps: under a nitrogen atmosphere, a predetermined amount of the starting material (0.01mol) and lithium methoxide (0.38g,0.01mol) were mixed with 20ml of methanol and reacted at room temperature for 8 hours. The obtained mixed solution is decompressed and dried at 40 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. Boron trifluoride tetrahydrofuran complex (1.47g, 0.0105mol) and 15ml THF (tetrahydrofuran) were added to the intermediate, the reaction was stirred at room temperature for 18 hours, the resulting mixture was dried under reduced pressure at 40 ℃ under a vacuum degree of about-0.1 MPa, and the resulting solid was washed three times with isopropyl ether, filtered and dried to obtain product P3. The yield of product P3 was 85%.

Example 4

Raw materials

The preparation method comprises the following steps: the raw material (0.01mol) and boron trifluoride diethyl etherate (1.49g, 0.0105mol) were mixed uniformly in 15ml of ethylene glycol dimethyl ether in a glove box, and reacted at room temperature for 12 hours. And drying the obtained mixed solution under reduced pressure at room temperature and under the vacuum degree of about-0.1 MPa to remove the solvent to obtain an intermediate. Dissolving lithium ethoxide (0.52g, 0.01mol) in 10ml ethanol, adding the mixture into the intermediate, stirring at room temperature for reaction for 12 hours, drying the obtained mixed solution under reduced pressure at 40 ℃ and under the vacuum degree of-0.1 MPa, washing the obtained solid with isopropyl ether three times, filtering and drying to obtain a product P4. The yield of product P4 was 89%.

Example 5

Starting materials

The preparation method comprises the following steps: the starting material (0.01mol) and boron trifluoride acetic acid complex (1.92g, 0.0102mol) were mixed uniformly in 15ml of THF (tetrahydrofuran) under an argon atmosphere, 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. Sodium acetate (1.36g, 0.01mol) was dissolved in 10ml of N, N-dimethylformamide and added to the intermediate, and stirred at 50 ℃ for reaction for 16 hours, the resulting mixture was dried under reduced pressure at 80 ℃ under a vacuum degree of about-0.1 MPa, and the resulting solid was washed three times with diphenyl ether, filtered, and dried to obtain a product P5. The yield of the product P5 was 86%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 1.

Example 6

Raw materials

The electrolyte P6 provided in this example was prepared from a raw material (0.01mol), boron trifluoride tetrahydrofuran complex, and lithium ethoxide by the same method as in example 1. The yield of product P6 was 87%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 2.

Example 7

Raw materials

The electrolyte P7 provided in this example was prepared from a raw material (0.01mol), boron trifluoride tetrahydrofuran complex, and lithium ethoxide by the same method as in example 1. The yield of product P7 was 85%.

Example 8

Raw materials

The electrolyte P8 provided in this example was prepared from the raw material (0.01mol), boron trifluoride diethyl etherate and lithium ethoxide by the same method as in example 4. The yield of product P8 was 82%.

Example 9

Raw materials

An electrolyte P9 provided in this example was prepared from the starting material (0.01mol), boron trifluoride etherate, and butyl lithium in hexane (c 1.6mol/L), and was prepared in the same manner as in example 2. The yield of the product P9 was 84%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 3.

Example 10

Raw materials

An electrolyte P10 provided in this example was prepared from the raw material (0.01mol) and lithium methoxide, boron trifluoride tetrahydrofuran in the same manner as in example 3. The yield of product P10 was 91%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 4.

Example 11

Raw materials

An electrolyte P11 provided in this example was prepared from the starting material (0.01mol), boron trifluoride etherate, and butyl lithium in hexane (c 1.6mol/L), and was prepared in the same manner as in example 2. The yield of product P11 was 93%.

Example 12

Raw materials

The electrolyte P12 provided in this example was prepared from a raw material (0.01mol), boron trifluoride tetrahydrofuran complex, and lithium ethoxide by the same method as in example 1. The yield of product P12 was 88%.

Example 13

Raw materials

The electrolyte P13 provided in this example was prepared from the raw material (0.01mol), boron trifluoride diethyl etherate and lithium ethoxide by the same method as in example 4. The yield of product P13 was 85%.

Example 14

Raw materials

The electrolyte P14 provided in this example was prepared from the raw material (0.01mol), boron trifluoride diethyl etherate and lithium ethoxide by the same method as in example 4. The yield of the product P14 was 80%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 5.

Example 15

Raw materials

An electrolyte P15 provided in this example was prepared from the raw material (0.01mol), lithium methoxide and boron trifluoride tetrahydrofuran by the same method as in example 3. The yield of product P15 was 77%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 6.

Example 16

The boron trifluoride organic salt containing the unsaturated heterochain structure is mainly used as an additive and salt in batteries (including liquid batteries, mixed solid-liquid batteries and all-solid batteries), and the boron trifluoride organic salt serving as the additive mainly plays a role in generating a passivation layer, and can dissociate ions to supplement consumed ions, so that the first-cycle efficiency, the first-cycle discharge specific capacity, the long-cycle stability and the rate capability of the batteries are greatly improved; the salt serving as electrolyte mainly plays a role of providing ion transmission and passivating an electrode, and is matched with the traditional salt to be used as double salt, so that the effect is good. The structure containing the polymerizable group can also initiate polymerization to form a polymer electrolyte, and the polymer electrolyte is applied to gel batteries and all-solid batteries. The performance of the invention is illustrated in experimental manner below.

The performance of the invention is illustrated in experimental manner below.

One, as an electrolyte additive

(1) Positive pole piece

Adding the active substance of the main anode material, the electronic conductive additive and the binder into a solvent according to the mass ratio of 95:2:3, wherein the solvent accounts for 65% of the total slurry by mass percent, and uniformly mixing and stirring to obtain anode slurry with certain fluidity; and coating the anode slurry on an aluminum foil, drying, compacting and cutting to obtain the usable anode piece. Lithium cobaltate (LiCoO) is selected as the active material₂LCO for short), lithium nickel cobalt manganese oxide (NCM811 for selection), lithium nickel cobalt aluminate (LiNi)_0.8Co_0.15Al_0.05O₂Abbreviated NCA) and lithium nickel manganese oxide (LiNi)_0.5Mn_1.5O₄Abbreviated LNMO), Na0.9[ Cu ]_0.22Fe_0.3Mn_0.48]O₂(NCFMO for short), Carbon Nanotubes (CNT) and SuperP are selected for the electron conductive additive, polyvinylidene fluoride (PVDF) is used as the binder, and N-methylpyrrolidone (NMP) is used as the solvent.

(2) Negative pole piece

Adding a main negative material active substance (except metal Li), an electronic conductive additive and a binder into solvent deionized water according to a ratio of 95:2.5:2.5, wherein the solvent accounts for 42% of the total slurry, and uniformly mixing and stirring to obtain negative slurry with certain fluidity; and coating the negative electrode slurry on copper foil, drying and compacting to obtain the usable negative electrode piece. Graphite (C), silicon carbon (SiOC450), metallic lithium (Li) and Soft Carbon (SC) are selected as the active materials, CNT and SuperP are used as the conductive agents, and carboxymethyl cellulose (CMC) and Styrene Butadiene Rubber (SBR) are used as the binders.

The anode and cathode systems selected by the invention are shown in table 1:

TABLE 1 Positive and negative electrode system

Positive and negative electrode system of battery	Positive electrode main material	Negative electrode main material
			A1	LCO	SiOC450
A2	NCM811	SiOC450
			A3	NCM811	Li
A4	NCA	C
			A5	LNMO	C
A6	LCO	Li
			A7	NCFMO	SC

(3) Preparing liquid electrolyte

P1-P15, organic solvent, conventional salt and conventional additive are mixed uniformly to obtain series electrolytes E1-E15, wherein the used solvent is Ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), Ethylene Carbonate (EC) and Propylene Carbonate (PC). The functional additive (i.e., conventional additive) is a fluoroethylene carbonateEsters (FEC), Vinylene Carbonate (VC), trimethyl phosphate (TMP), ethoxypentafluorocyclotriphosphazene (PFPN), vinyl sulfate (DTD); conventional salts are lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LiODFB), lithium bis (fluorosulfonylimide) (LiFSI), lithium hexafluorophosphate (LiPF)₆) Lithium bis (trifluoromethyl) sulfonimide (LiTFSI), sodium hexafluorophosphate (NaPF)₆). The specific components and ratios are shown in table 2.

TABLE 2 electrolytes E1 to E15 formulated with P1 to P15 as additives

Note: 1M means 1 mol/L.

Comparison sample: replacing P1-P15 with blanks according to the proportion of E1-E15 (namely, not adding P1-P15), and obtaining corresponding conventional electrolyte reference samples L1-L15.

(4) Button cell assembly

Electrolyte series E1-E15 containing the structure of the embodiment as an additive and conventional electrolytes L1-L15 were assembled into button cells in a comparative manner, specifically as follows: negative electrode shell, negative electrode pole piece, PE/Al₂O₃A button cell is assembled by a diaphragm, an electrolyte, a positive pole piece, a stainless steel sheet, a spring piece and a positive shell, and a long circulation test is carried out at room temperature, wherein the circulation modes are 0.1C/0.1C1 week, 0.2C/0.2C5 week and 1C/1C44 week (C represents multiplying power), the positive pole piece is a round piece with the diameter of 12mm, the negative pole piece is a round piece with the diameter of 14mm, the diaphragm is a round piece with the diameter of 16.2mm, and is a commercial Al round piece₂O₃a/PE porous separator.

The battery systems prepared from E1-E15 are batteries 1-15, respectively, and the battery systems prepared from L1-L15 are comparative batteries 1-15, respectively. The specific configuration and voltage range of the cell are shown in table 3.

The results of the first cycle specific discharge capacity, the first cycle efficiency, and the capacity retention rate at 50 cycles of the batteries 1 to 15 and the comparative batteries 1 to 15 at room temperature are shown in table 4.

TABLE 3 arrangement and test mode for batteries 1-15 of examples and comparative batteries 1-15

TABLE 4 comparison of test results for batteries 1-15 of examples and comparative batteries 1-15

From the test results of the battery and the comparative battery, in the button battery, when the positive and negative electrode systems are the same, the first-cycle efficiency, the specific discharge capacity and the capacity retention rate of the battery using the structures P1-P15 as the electrolyte additive are much better than those of the battery without the electrolyte additive, and the performance of the battery is superior to that of the conventional additive at present. In addition, the use of boron-containing salt additives in the presence of conventional additives shows a synergistic effect and the battery shows more excellent electrochemical performance.

II, salts as electrolytes

(1) Preparing liquid electrolyte

P6, P10, P12 and P14, wherein the series of electrolytes R6, R10, R12 and R14 are obtained by uniformly mixing organic solvents, conventional additives and conventional salts, and the series of conventional electrolytes Q6, Q10, Q12 and Q14 are obtained by uniformly mixing conventional salts, organic solvents and conventional additives, and the solvents and functional additives used comprise the solvents and functional additives described in the "one" of the embodiment. The specific components and ratios of the liquid electrolyte are shown in table 5.

Table 5 Synthesis of substance P as salt formulated electrolyte

(2) Battery assembly

The obtained series of liquid electrolytes R (shown in table 5) and the conventional liquid electrolyte Q (shown in table 5) were assembled into a button cell, and the positive and negative electrodes, the size of the separator, the assembly method, and the battery cycle were the same as those of the button cell shown in "one" of this example, i.e.,

batteries

6, 10, 12, and 14 and the corresponding comparative batteries, respectively. Specific configurations, cycling modes and voltage ranges of the batteries are shown in table 6, and specific first-cycle discharge capacity, first-cycle efficiency and 50-cycle capacity retention rate results of the batteries and comparative batteries at room temperature are shown in table 7.

Table 6 arrangement and test mode of example and comparative example cells

Table 7 comparison of test results for example and comparative batteries shown in table 6

In conclusion, the boron-containing salt provided by the invention is independently used as a salt or forms a double salt with a conventional salt in a non-aqueous solvent, ions are easily solvated, higher ionic conductivity is provided for a battery, the stability is high, in a liquid battery system with LCO and NCM811 as positive electrodes and SiOC450 and Li as negative electrodes, the electrochemical performance is very excellent, the first-effect and first-cycle discharge specific capacity and the capacity retention rate are higher, and the performance is equivalent to or superior to that of a battery corresponding to the conventional salt.

Thirdly, as a salt in a solid electrolyte

(1) Preparation of Polymer electrolyte Membrane

Dissolving the structure, the polymer and the inorganic filler provided by the invention in DMF (dimethyl formamide) according to a certain proportion in an environment with a dew point lower than-60 ℃, and stirring and mixingMixing, coating to form a film, rolling and drying to obtain polymer electrolyte films G9, G11, G13 and G15 and polymer comparative electrolyte films G '1-G' 2, wherein the specific components, the proportions and the like are shown in Table 8. Wherein the polymer is polyethylene oxide (PEO, molecular weight is 100 ten thousand), the inorganic filler is LLZO of 160nm, i.e. crystal form of Li with median particle diameter of 160nm as cubic phase₇La₃Zr₂O₁₂An inorganic oxide solid electrolyte.

TABLE 8 concrete composition and compounding ratio of polymer electrolyte

Polymer electrolyte	Polymer and method of making same	Salt (salt)	Inorganic filler	Mass ratio of	Solvent(s)
						G9	PEO100 ten thousand	P9	160nmLLZO	4.2：1：0.8	DMF
G11	PEO100 ten thousand	P11	/	4.2：1	DMF
						G13	PEO100 ten thousand	P13	160nmLLZO	4.2：1：0.8	DMF
G15	PEO100 ten thousand	P15	/	4.2：1	DMF
						G’1	PEO100 ten thousand	LiTFSI	160nmLLZO	4.2：1：0.8	DMF
G’2	PEO100 ten thousand	LiTFSI	/	4.2：1	DMF

(2) Preparation of positive and negative pole pieces

In an environment with a dew point lower than-60 ℃, mixing a positive electrode main material active substance, a polymer + salt (the proportion is the same as that of a polymer electrolyte membrane), an electronic conductive additive and a binder according to a mass ratio of 91.3: 4.8: 2.1: 1.8 stirring and mixing the mixture in a solvent, coating the mixture on an aluminum foil, drying and rolling the aluminum foil to obtain the all-solid-state positive pole piece. Lithium cobaltate (LiCoO2, LCO for short) or lithium nickel manganese cobalt oxide (NCM811 for short) was selected as the active material, SuperP was used as the electron conductive additive, and polyvinylidene fluoride (PVDF) was used as the binder.

And pressing a 50-micron-thick lithium metal sheet on a copper foil to form a negative pole piece.

(3) Battery assembly and testing

The polymer electrolyte membrane and the positive and negative pole pieces are cut and assembled into the 1Ah all-solid-state soft package battery, and the battery is subjected to 50 ℃ long cycle test in the cycle mode of 0.1C/0.1C2 weeks and 0.3C/0.3C48 weeks. The specific assembly system and test method of the battery are shown in table 9, and the test results are shown in table 10.

Table 9 configuration and test mode for example and comparative batteries

TABLE 10 comparison of test results for cells and comparative cells in TABLE 9

From the data in tables 9 and 10, it can be seen that the batteries prepared from P9, P11, P13 and P15 have excellent long-cycle stability and the performance is superior to that of the battery corresponding to LiTFSI. Probably, the sulfur-based boron trifluoride salt has excellent ion transmission performance, and can form a compact and stable passivation layer on the surface of the positive electrode to prevent the positive electrode active material from catalytically decomposing various components of the electrolyte.

Four, single ion conductor polymer electrolyte

(1) Preparation of electrolyte

Monomers P1-P4, P7, P8, a plasticizer, a battery additive, salt and an initiator are uniformly stirred to form a precursor solution, and precursors S1-S4, S7 and S8 are obtained, and the specific preparation ratio is shown in Table 11. S1-S4, S7 and S8 are used for preparing the polymer electrolyte through free radical polymerization, and the initiator used is Azobisisobutyronitrile (AIBN) or Benzoyl Peroxide (BPO).

TABLE 11 precursor solution composition

(2) Battery assembly

Electrolyte precursor solutions S1-S4, S7 and S8 obtained in Table 11 are assembled into soft package batteries respectively, namely batteries (namely, embodiments) 1-4, 7 and 8; the method comprises the following specific steps: assembling a positive pole piece with the size of 64mm multiplied by 45mm, a negative pole piece with the size of 65mm multiplied by 46mm and a diaphragm into a 2Ah soft package battery core, and performing lamination, baking, liquid injection and formation processes to obtain the secondary battery, wherein the battery assembly system is A2, and the diaphragm is made of commercial PE/Al₂O₃A porous membrane.

(3) Battery testing

After the secondary batteries prepared in examples 1 to 4, 7 and 8 were completely cured, the first-cycle discharge capacity, the first-cycle efficiency and the capacity retention rate at 50 cycles of the batteries were tested at room temperature, and the test voltage ranges were 3.0 to 4.2V, wherein the cycle patterns were 0.1C/0.1C2 cycles and 0.3C/0.3C48 cycles (C represents the rate), and the test results are shown in Table 12

Table 12 test results of the batteries of the examples

As shown in table 12, it is found from the test data in the example battery that the precursors S1 to S4, S7, and S8 composed of the polymerizable monomers P1 to P4, P7, and P8, after in-situ curing, are used as polymer electrolytes, and in a solid-state battery system in which NCM811 is a positive electrode and silicon oxycarbide (SiOC450) is a negative electrode, the electrochemical performance is very excellent, and the first-pass discharge capacity, the first-week discharge capacity, and the capacity retention rate are relatively high. Example 1a solid electrolyte having excellent performance can be obtained after polymerization, and also when additionally used in combination with a conventional salt, the battery exhibits more excellent electrochemical performance due to an increased amount of dissociated ions.

In addition, the application also shows the effect graph of some embodiments as additives, salts and polymer electrolytes. Fig. 7-10 are graphs comparing the performance of battery 6/9/11/12 made with example 6/9/11/12 as an electrolyte additive to a corresponding comparative battery 6/9/11/12 that did not contain example 6/9/11/12 of the present invention. FIGS. 11-12 are graphs comparing the effect of the battery 6/10 made from the liquid electrolyte salt of example 6/10 with a corresponding comparative battery 6/10 that did not contain the inventive example 6/10. Fig. 13 is a graph comparing the effects of example 15 made as a battery 15 with salt in solid electrolyte and a comparative battery 2 made with LiTFSI as the salt. FIG. 14 is a graph showing the effects of the monomer of example 3 polymerized to form a battery 3 as a polymer electrolyte. It can be seen from FIGS. 7-14 that the structure of the present invention has excellent effects.

The first cycle efficiency, specific discharge capacity, capacity retention rate and other properties have direct and significant influence on the overall performance of the battery, and directly determine whether the battery can be applied or not. Therefore, it is the goal or direction of many researchers in this field to improve these properties, but in this field, the improvement of these properties is very difficult, and generally about 3-5% improvement is a great progress. In the early experimental data, the data are surprisingly found to be greatly improved compared with the conventional data, particularly when the additive is used as an electrolyte additive, the performance is improved by about 5-30%, and the additive and the conventional additive are combined to be used for showing better effect. The examples section only shows additives as liquid electrolytes, but boron trifluoride salts in the present application are also additives that can be used as solid electrolytes, which are not shown here for reasons of space. More surprisingly, the component can also be used as salt in electrolyte, and the effect is very good, and tests show that the component is superior to the existing mature component. In addition, the boron trifluoride salt can also be applied to a solid-state battery, and has an excellent effect and an excellent application prospect. More importantly, the structural type of the application is 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 brought for further research, and the application can also have multiple purposes; has great significance.

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

the effects are excellent and other structures similar to those described in any of the paragraphs of this application also have better effects, but for reasons of space, the effects of the structures protected by the present invention will be described only by way of example in examples 1 to 15. And the preparation methods of examples 1-15 and the above-listed structures are all that the boron trifluoride organic salt is obtained by reacting the raw material, M source and boron trifluoride compound, i.e. the-SH in the raw material is changed into-SBF₃M, M may be Li⁺、Na⁺And the other structures are not changed, and the concrete reference can be made to the embodiments 1 to 5. The structures not shown in the examples were prepared in the same manner.

The raw materials used in the examples can be purchased or simply prepared, and the preparation processes are all the prior art, so the detailed description is not provided in the specification.

It should be noted that, the applicant has performed a great number of tests on the series of structures, and sometimes, for better comparison with the existing system, there are cases where the same structure and system are tested more than once, and therefore, there may be some error in the tests performed at different times.

Finally, it should be noted that: the above-mentioned embodiments are only used for illustrating the technical solution of the present invention, and not for limiting the same; although the present 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 solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An electrolyte containing an unsaturated heterochain structure, wherein the electrolyte comprises a boron trifluoride salt, and the structure of the boron trifluoride salt is shown as a general formula I:

MF₃BS-R₁-R is of the general formula I

Wherein M is a metal cation; r is independently a first chain containing no or at least one atom; r₁Independently a second chain free or containing at least one atom; h on any one C of the first and second chains may be independently substituted with a substituent group including H, a chain substituent group containing at least one atom, and a cyclic substituent group; the first chain, second chain, and chain substituents contain at least one heteroatom other than carbon and at least one unsaturated bond, including double or triple bonds.

2. The electrolyte according to claim 1,

in the general formula I, the heteroatom comprises halogen atoms, S, N, O, P, Se, Ca, Al, B or Si;

3. The electrolyte of claim 2, wherein in formula I, R is 1 to 20 atomsAn unsaturated heterochain; r₁Is an unsaturated heterochain of 0 to 5 atoms; the hetero atom includes a halogen atom, S, N, O, P, Ca, B or Si.

4. The electrolyte of claim 3, wherein the chain substituents are selected from the group consisting of halogen atoms, ether oxy groups, ether thio groups, nitro groups, cyano groups, carbonyl groups, ester groups, aldehyde groups, disubstituted amino groups, sulfoalkanes, amides, sulfonamide groups, sulfo groups, alkyl groups, heteroalkyl groups, alkenyl groups, heteroalkenyl groups, alkynyl groups, heteroalkynyl groups, alkinyl groups, ═ O, ═ S, and,

wherein the ester group includes carboxylate, carbonate, sulfonate and phosphate, and the heteroatoms in the heteroalkyl, heteroalkenyl and heteroalkynyl groups are selected from the heteroatoms recited in claim 2 or 3; r is₂、R₃And R₄Independently H, alkyl, heteroalkyl, alkenyl, heteroalkenyl, alkynyl, heteroalkynyl and alkenynyl, preferably R₄In non-H structures, the salt substituents include, but are not limited to, sulfate, sulfonate, sulfonimide, carbonate, carboxylate, thioether, oxoether, ammonium, hydrochloride, nitrate, azide, silicate, phosphate.

5. The electrolyte of claim 4, wherein the general formula I comprises the following structure:

(A)

(B)

(C)

(D)

in the above (A), (B), (C) and (D), Q represents-SBF₃M or-R₁-SBF₃M；A₁-A₂₉Independently selected from the group defined for the substituents in any one of claims 1 to 3, preferably selected from H, C₁-C₆Alkyl or said cyclic substituent;

and in (B), at least one substituent Z in each structure is a group containing ═ O, -N ═ O, ═ S, ═ N-R₄-P ═ O, nitro, ester, cyano, heteroalkenyl, heteroalkynyl, aldehyde, amide, sulfonamide, or sulfo; in (C), at least one of each structureThe substituent Z is a substituent containing an unsaturated bond; in (D), at least one substituent Z in each structure is a substituent containing a heteroatom selected from the group consisting of the heteroatoms as defined in any one of claims 1 to 3.

6. The electrolyte of claim 5, wherein in (A) - (D), A in each structure₁-A₂₉Each independently is a second substituent selected from the group consisting of H, a halogen atom, an alkyl group, an alkoxy group, an alkylthio group, an ethenyl group, a propenyl group, an ethynyl group, a propynyl group, a disubstituted amino group, a nitro group, a cyano group, an ester group, an aldehyde group, a sulfoalkane, an amide, a sulfonamide group, a sulfo group, O, S, a,

7. The electrolyte of claim 6, wherein the electrolyte is characterized by being prepared at (A), (B), (C) and C)A) In (D), the second substituent is selected from H, a halogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a methoxy group, an ethoxy group, a vinyl group, a propenyl group, an ethynyl group, an O group, a phenyl group, or a group in which H of any one C of the second substituents is substituted with a halogen; the first substituent is selected from H, alkyl, halogen atom, nitro, aldehyde group, haloalkyl, alkenyl, alkynyl, ester group, carbonyl group, ═ O, ═ S, ═ CH₂Alkylthio, cyano, sulfonyl or alkoxy; and in (B), at least one substituent Z in each structure is ═ O, cyano, aldehyde; in (C), at least one substituent Z in each structure is ═ O, vinyl, ethynyl; in (D), at least one substituent Z in each structure is ═ O, a halogen atom, or an alkoxy group;

8. The electrolyte of any one of claims 1-7, wherein M in formula I comprises Na⁺、K⁺、Li⁺、Mg²⁺Or Ca²⁺Preferably Na⁺、K⁺Or Li⁺；

9. A method for producing an electrolyte containing an unsaturated heterochain structure according to any of claims 1 to 8, wherein the electrolyte is obtained by reacting a mercapto group, a boron trifluoride compound and a source of M.

10. Use of an electrolyte containing an unsaturated heterochain structure according to any of claims 1 to 8 in a secondary battery, characterized in that the use is: the boron trifluoride salts can be used both as additives for electrolytes and as salts; the polymerizable monomer in the general formula I can be polymerized and then used as a single-ion conductor and polymer framework;

preferably, the application comprises application in a liquid electrolyte, a gel electrolyte, a mixed solid-liquid electrolyte, a quasi-solid electrolyte, an all-solid electrolyte, each of which independently comprises an electrolyte containing an unsaturated heterochain structure according to any one of claims 1 to 8;

preferably, the application also includes application as a battery or a battery pack, the battery comprises the electrolyte containing the unsaturated heterochain structure in any one of claims 1 to 8, and a positive electrode, a negative electrode and a packaging shell, and the liquid electrolyte, the gel electrolyte, the mixed solid-liquid electrolyte, the quasi-solid electrolyte and the all-solid electrolyte can be applied to the liquid battery, the mixed solid-liquid battery, the semi-solid battery, the gel battery, the quasi-solid battery and the all-solid battery; the battery pack includes the battery.