CN114649581A

CN114649581A - Electrolyte containing five-membered cyclic nitrogen-based salt structure and preparation method and application thereof

Info

Publication number: CN114649581A
Application number: CN202011496920.9A
Authority: CN
Inventors: 杨萌; 程勇斌; 俞会根
Original assignee: Beijing WeLion New Energy Technology Co ltd
Current assignee: Beijing WeLion New Energy Technology Co ltd
Priority date: 2020-12-17
Filing date: 2020-12-17
Publication date: 2022-06-21
Anticipated expiration: 2040-12-17
Also published as: CN114649581B

Abstract

The application provides an electrolyte containing a five-membered ring nitrogen-based salt 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 nitrogen-based 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, the passivation layer contains M ions, and the ions provided by the electrode are less consumed in the film forming process, so that the first-cycle efficiency and the cycle performance of a battery can be obviously improved; when used as a salt in an electrolyte, the boron trifluoride salts provided herein haveBetter ion transmission and stable electrochemical performance. The nitrogen-based boron trifluoride salt can be applied to liquid batteries, solid-liquid hybrid batteries, semi-solid batteries, gel batteries, quasi-solid batteries and all-solid batteries, is beneficial to improving the energy density, the cycle stability and the service life of the batteries, and has the advantages of low raw material price, simple synthesis and purification process and better economic benefit.

Description

Electrolyte containing five-membered cyclic nitrogen-based salt structure and preparation method and application thereof

Technical Field

The application relates to the technical field of batteries, in particular to an electrolyte containing a five-membered ring nitrogen-based salt structure and a preparation method and application thereof.

Background

Batteries have become a conventional way of storing energy for portable devices. The development of intelligent electronic technology has placed higher demands on the energy density of batteries. In addition, with the further push of automobile manufacturers such as Tesla (Tesla), electric automobiles become a new battery application field. Each application field of the battery requires consideration of electrochemical performance, safety and cost of the battery. In any event, it is imperative that batteries with higher energy densities and longer lifetimes be used to meet the ever-increasing demand for energy.

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), and a Lithium Nickel Manganese Oxide (LNMO), and a negative electrode material, such as metal lithium, graphite, silicon oxycarbide, and the like, 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.

The electrolyte is largely divided into a liquid electrolyte and a solid electrolyte, and the liquid electrolyte has the remarkable advantages of high conductivity and good wettability to the inside of the electrode. However, the organic solvent in the liquid electrolyte is flammable, easily causes uncontrollable side reactions, unstable electrode interface and serious gas generation, which leads to serious capacity decline, low cycle life of the battery and poor safety. The above-mentioned problems can be remarkably suppressed by using a non-flammable solid electrolyte, and further, it has been proposed to suppress the growth of lithium dendrites with a solid electrolyte. Solid electrolytes can be divided into two broad categories, organic polymer electrolytes and inorganic (sulfide and oxide) electrolytes. The polymer has better flexibility, is easy to process and is beneficial to interface contact with an electrode, but is subjected to ion electricity at room temperatureThe conductivity is low, the thermal stability is limited, and the electrochemical window is narrow; sulfide has high ionic conductivity and good processing capacity, but most sulfides are unstable in air and generate toxic H with water molecules₂S gas, and therefore requires a very harsh processing environment; the oxide has excellent chemical and thermal stability, high voltage resistance, high ionic conductivity, poor flexibility and large interface resistance. Therefore, liquid electrolytes are still mainly used, and in order to improve the cycle stability of liquid batteries, various functional additives, such as FEC (fluoroethylene carbonate), VC (vinylene carbonate), VEC (vinylene carbonate), DTD (vinyl sulfate), and the like, need to be added to the electrolytes, and for example, the SEI passivation film formed on the surface of the negative electrode mainly contains various inorganic components Li₂CO₃、LiF、Li₂O, LiOH, and various organic components ROCOOLi, ROLi, and ROCOOLi, but the first cycle efficiency and specific discharge capacity are still slightly low because active ions derived from the positive electrode are consumed. If the added additive can form a passivation layer which is conductive to ions and good in stability on the surface of the electrode, and the ions from the electrode are less consumed, the oxidation/reduction decomposition of the anode and cathode materials to the electrolyte can be effectively prevented, so that 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 are 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.

-NBF₃Is a strongly polar group capable of forming a salt with a cation, thus, -NBF₃M 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 radical compounds were studied sporadically, and no results for industrial application were found at present.

Patent No. CN108878975A discloses an electrolyte additive comprising a pyridine-boron trifluoride complex compound and a halosilane, wherein the pyridine-boron trifluoride complex compound is at least one selected from compounds of the formula shown in formula (1): wherein R is₁₁、R₁₂、R₁₃、R₁₄、R₁₅Each independently selected from the group consisting of a hydrogen atom, a halogen, a cyano group, a sulfonic group, a sulfonyl group, and a substituted or unsubstituted C_1～20Alkyl, substituted or unsubstituted C_2～20Alkenyl, substituted or unsubstituted C_6～26Aryl, substituted or unsubstituted C_1～20Alkoxy, substituted or unsubstituted C_6～26An aryloxy group; the substituent is selected from halogen, sulfonic group or sulfonyl. However, the compound is a complex compound, is not a nitrogen-based 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-NBF₃M salt has a good effect in the battery, so that a special formation team carries out special research on the negative-containing boron fluoride (NBF)₃M salt and achieves better research results.

The present application is directed to-NBF₃The structure of M on the five-membered ring was independently studied. Presence of-NBF on the five-membered ring₃M, an effect different from that of other structures may be produced. Therefore, the present application identifies the subject as a direct or indirect attachment of-N-BF to a five-membered ring structure₃M, thereby more specifically determining-N-BF₃The specific case when M is present in the five-membered ring.

Disclosure of Invention

In view of this, embodiments of the present application provide an electrolyte containing a five-membered cyclic nitrogen-based salt 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 a five-membered cyclic nitrogen-based salt structure, which comprises a boron trifluoride salt, wherein the structure of the boron trifluoride salt is shown as a general formula I:

wherein M is a metal cation; r₁、R₂、R₃、R₄Is a carbon atom or a heteroatom selected from S, N, O, P, Se, Ca, Al, B or Si; r₅As a substituent, any one H on the representative ring can be independently substituted by a substituent, and the substituent replaces one H or two H, and in the case where the substituent replaces two H, each substituent is the same or different.

Further, N and R₁And N and R₄Are connected through a single bond, R₁And R₂R, m₂And R₃R is₃And R₄Are connected by single or double bonds.

Further, the substituent is selected from a chain substituent, a ring substituent, a salt substituent and a group in which one or more of H connected to a C atom is substituted with a halogen atom.

Further, the chain-type substituent is selected from H, a halogen atom, a carbonyl group, an ester group, an aldehyde group, an ether oxy group, an ether thio group, ═ O, ═ S, and,

Nitro, cyano, amide, primary amine, tertiary amine, secondary amine, sulfonamide, sulfolane, hydrazino, diazo, hydrocarbyl, heterohydrocarbyl;

wherein R is₁₁And R₁₂Independently is H or a hydrocarbyl group; ester groups include carboxylic acid esters, carbonic acid esters, sulfonic acid esters, and phosphoric acid esters; hydrocarbyl includes alkyl, alkenyl, alkynyl, and alkenylalkynyl; a heterohydrocarbyl group is a hydrocarbyl group containing at least one heteroatom; the heteroatoms in the heterohydrocarbyl group are selected from halogen, N, P, S, O, Se, Al, B, and Si;

the ring substituent comprises a three-to eight-membered ring and a polycyclic ring formed by at least two monocyclic rings;

the salt substituent comprises sulfate, sulfonate, sulfimide salt, carbonate, carboxylate, thioether salt, oxygen ether salt, nitrogen salt, hydrochloride, nitrate, azide salt, silicate and phosphate;

preferably, the carbonyl group is

The ester group is-R₁₃COOR₁₄、-R₁₃OCOR₁₄、-R₁₃SO₂OR₁₄、 -R₁₃O-CO-OR₁₄Or

Amide is

Sulfonamide group of

The sulfoalkane is

Diazo is-N ═ N-R₁₆With an ether oxygen radical of-R₁₃OR₁₄The etherthio radical is-R₁₃SR₁₄(ii) a Wherein R is₁₃、R₁₄、R₁₅、R₁₆、R₁₇、R₁₈、R₁₉Independently is an alkyl, alkenyl, alkynyl or alkenynyl group or heterohydrocarbyl group having from 1 to 20 carbon atoms which includes alkyl, alkenyl, alkynyl or alkenynyl groups and which includes heteroalkyl, heteroalkenyl or heteroalkynyl groups, with substituents optionally attached to the rings; r directly linked to N₁₆、R₁₇、R₁₈、 R₁₉The radicals can also be H or a metal ion, R being directly bonded to O₁₁、R₁₂、R₁₃The group can also be a metal ion.

Further, halogen atoms include F, Cl, Br, I;

diazo-N ═ N-R₁₆R in (1)₁₆It can also be phenyl or phenyl with attached substituents;

cyano radicals selected from-CN, -CH₂CN、-CH₂CH₂CN or-N (CH)₃)CH₂CH₂CN；

Preferably, the alkyl group is selected from the group consisting of methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, -CH₂C(CH₃)₃、-CH(CH₃)₂、 -C(CH₃)₂CH₂C(CH₃)₃、-C(CH₃)₂CH₂CH₃、-CH₂(CH₂)₄CH(CH₃)₂(ii) a The heteroalkyl group is selected from-CH₂CH₂-O-NO₂、-CO-CH₂-Cl、-CO-CH₂-Br、-COCH₂(CH₂)₅CH₃、 -COCH(CH₃)CH₂CH(CH₃)CHCl₂CH₂Cl、-CH₂NO₂、-Z₂CF₃、-CH₂Z₂、-CH₂Z₂CH₃、-CH₂CH₂Z₂、 -Z₂(CH₂CH₃)₂、-CH₂N(CH₃)₂、-CH₂Z₂CH(CH₃)₂、-COCH₂CH(CH₃)₂、-OCH₂(CH₂)₆CH₃、 -CH₂(CH₃)Z₂CH₂-、-CH₂(CH₃)Z₂CH₂(CH₃)-、-CH₂CH₂Z₂CH₂-、-CH₂CH(CH₃)Z₂CH₂-、 -CH(CH₃)CH₂Z₂CH₂-；

The alkenyl group is selected from vinyl, propenyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenylDecenyl, undecenyl, dodecenyl, tridecenyl, tetradecenyl, pentadecenyl, hexadecenyl, heptadecenyl, octadecenyl, 1, 3-hexadienyl, -C (CH)₃)＝CH₂、-C(CH₃)＝CH₂、-CH₂CH＝C(CH₃)CH₂CH₂CH＝C(CH₃)₂、 -CH₂CH＝CH(CH₃)₂、-CH₂CH＝CH-CH₂CH₂-；

The heteroalkenyl group is selected from-N ═ CHCH₃、-OCH₂CH＝CH₂、-CH₂-CH＝CH-Z₂CH₂-、-CH＝CHCH₂-CH₂Z₂CH₂-；

The alkynyl is selected from ethynyl, propynyl, butynyl, pentynyl, hexynyl, heptynyl;

the heteroalkynyl is selected from the group consisting of-C ≡ CCH₂CH₂CH₂Z₂CH₂CH₂-、-N(CH₃)CH₂CH₂CN、-C≡CCH₂Z₂CH₂CH₂-、 -C≡C-Si(CH₃)₃；

The alkenylalkynyl is selected from-C ≡ CCH ═ CHCH₂-、-C≡CCH₂CH＝CHCH₂Z₂CH₂-、-C≡CCH₂CH₂CH＝CHCH₂-；

The cyclic substituents include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and polycyclic; wherein the cyclopropyl group is selected from the group consisting of a cyclopropane group, an oxirane group, a substituted cyclopropane group, and a substituted cyclopropane group,

The cyclobutyl group is selected from the group consisting of cyclobutyl, cyclobutylheteroalkyl, cyclobutenyl, cyclobutylheteroalkenyl; cyclopentyl is selected from cyclopentyl, cyclopentenyl, cyclopentadienyl, pyrrolyl, dihydropyrrolyl, tetrahydropyrrolyl, furyl, dihydrofuryl, tetrahydrofuryl, thienyl, dihydrothienyl, tetrahydrothienyl, imidazolyl, thiazolyl, dihydrothiazolyl, tetrahydrothiazolyl, isothiazolyl, dihydroisothiazolyl, triazolyl, tetrazolyl, pyrazolyl, oxazolyl, thiazolyl, or mixtures thereof,Dihydrooxazolyl, tetrahydrooxazolyl, isoxazole, dihydroisoxazole, thiadiazole, selenadiazole, 1, 3-dioxacycloalkane, 1, 3-dithiocycloalkane, diazosulfide, and diazosulfide,

Cyclohexyl is selected from the group consisting of phenyl, pyridyl, dihydropyridinyl, tetrahydropyridyl, pyrimidinyl, dihydropyrimidyl, tetrahydropyrimidinyl, hexahydropyrimidyl, p-diazabenzene, cyclohexane, cyclohexenyl, 1, 3-cyclohexadiene, 1, 4-cyclohexadiene, piperidine, pyran, dihydropyran, tetrahydropyran, morpholine, piperazine, pyrone, pyridazine, dihydropyridazine, tetrahydropyridazine, pyrazine, dihydropyrazine, tetrahydropyrazine, triazine, pyridiniumyl, pyrimidiniumyl, piperidinumyl, piperidinium, piperazindolizinyl, dihydropyraumyl, and piperazinol,

Polycyclic ring selected from biphenyl, naphthyl, anthryl, phenanthryl, quinonyl, pyrenyl, acenaphthenyl, carbazolyl, indolyl, isoindolyl, quinolyl, purinyl, nucleobase, benzoxazole,

Wherein Z is₂is-O-, -S-S-),

R₂₉、R₃₀、R₃₁、R₃₂Independently selected from methyl, ethyl, propyl, isopropyl, butyl, fluoromethyl, fluoroethyl, methoxy, ethenyl, propenyl, or a metal ion;

any one ring of the ring substituents may be connected with a first substituent, the type of the first substituent and R₂The defined substituents are identical; preferably, the first substituent is selected from the group consisting of H, a halogen atom, methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, n-pentyl, isopentyl, sec-pentyl, neopentyl, fluoromethyl, fluoroethyl, methoxy, ethoxy, nitro, alkeneAlkyl, alkynyl, ester group, sulfonate, sulfoalkane, amido, cyano, aldehyde group, -SCH₃、-COOCH₃、COOCH₂CH₃、 -OCF₃、＝O、-N(CH₃)₂、-CON(CH₃)₂、-SO₂CH₃or-SO₂CH₂CH₃；

Any one ring of the ring substituents is independently connected with the substituted unsaturated heterocyclic ring through any one of the following connecting groups: -CH₂-、-CH₂CH₂-, propyl, butyl, ethylene, propylene, butene, acetylene, propyne, -COO-, -CO-, -SO₂-、-N＝N-、-O-、-OCH₂-、-OCH₂CH₂-、-CH₂OCH₂-、-COCH₂-、-CH₂OCH₂CH₂-、-OCH₂CH₂O-、 -COOCH₂CH₂-、-S-、-S-S-、-CH₂OOC-、-CH＝CH-CO-、

Or a single bond; r₂₉Independently selected from methyl, ethyl or propyl; r₃₃Independently selected from any one of the linking groups; r₃₄、R₃₅Independently an alkyl group or a ring.

Preferably, R₁、R₄Is a carbon atom, and R₁、R₄Attached substituent R₅Is ═ O. In this case, the structure of the electrolyte may be expressed as

R₅Selected from the substituents described in any of the preceding paragraphs.

More preferably, R₂、R₃Is a carbon atom, in which case the structure of the electrolyte can be represented as

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 of the carbon atoms in any one of formula I are independently replaced by fluorine atoms.

The present application also provides a method for preparing the five-membered cyclic nitrogen-based salt structure as described above, which is obtained by reacting a starting material containing-NH with a boron trifluoride-based compound and an M source.

The present application also provides an application of the electrolyte containing a five-membered cyclic nitrogen-based salt structure as described above in a secondary battery, the application being: the boron trifluoride salts can be used both as additives and as salts for electrolytes.

Further, the application includes application in liquid electrolyte, gel electrolyte, mixed solid-liquid electrolyte, quasi-solid electrolyte, all-solid electrolyte, which independently include the electrolyte containing nitrogen-based salt structure as described in any of the above paragraphs.

Further, the application also includes the application as a battery or a battery pack, the battery comprises the electrolyte containing the nitrogen-based salt structure as described in any paragraph above, and a positive electrode, a negative electrode and a packaging shell, and the electrolyte can be applied to a liquid battery, a hybrid 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 invention has the following main beneficial effects:

the electrolyte in this application inventively converts-NBF₃M is compounded in a five-membered ring structure, and the structural effect protected by the invention is more prominent.

1. The nitrogen-based boron trifluoride compound can be used as an additive in a battery, can form a stable and compact passive film on the surface of an electrode of the battery, prevents an electrolyte from being in direct contact with an electrode active substance, inhibits the decomposition of each component of the electrolyte, widens the electrochemical window of the whole electrolyte system, and can obviously improve the discharge specific capacity, the coulombic efficiency and the cycle performance of the battery; in addition, the nitrogen-based boron trifluoride compound is an ionic conductor, is used as an additive, forms a passivation layer on the surface of an electrode, simultaneously consumes few active ions coming out of a positive electrode, and can obviously improve the first coulombic efficiency and the first-cycle specific discharge capacity of the battery. And when the electrolyte containing the nitrogen-based boron trifluoride compound, the conventional high-voltage high-specific-volume positive electrode material and the conventional 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.

2. 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.

3. The boron trifluoride salt has the advantages of rich raw material source, wide raw material selectivity, low cost, simple preparation process, simple reaction, mild conditions and excellent industrial application prospect.

4. The lithium-ion battery can also adopt metals such as sodium and potassium except traditional lithium to form salts, so that more possibilities are provided for later application, cost control or raw material selection, and the like, and the lithium-ion battery has great significance.

Therefore, the nitrogen-based boron trifluoride compound provided by the application has multiple purposes in the battery, 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, can improve the electrochemical performance of the battery, and comprises the steps of improving the energy density of the battery, improving the cycle stability and prolonging the service life of the battery, and has the advantages of simple synthesis process, low raw material price and good economic benefit.

Drawings

FIG. 1 is a nuclear magnetic hydrogen spectrum of a product shown in example 1 of the present application; FIG. 2 is a nuclear magnetic hydrogen spectrum of the product shown in example 3 of the present application; FIG. 3 is a nuclear magnetic hydrogen spectrum of the product shown in example 6 of the present application; FIG. 4 is a nuclear magnetic hydrogen spectrum of a product shown in example 13 of the present application;

FIGS. 5-8 are graphs comparing the performance of a battery 1/2/5/13 made in accordance with example 1/2/5/13 as an electrolyte additive to a corresponding comparative battery 1/2/5/13 which did not contain example 1/2/5/13 of the present invention;

FIGS. 9-10 are graphs comparing the effect of the battery 1/3 made from the liquid electrolyte salt of example 1/3 with a corresponding comparative battery 1/3 that did not contain the inventive example 1/3;

fig. 11 is a graph comparing the effects of example 1 made as a salt in a solid electrolyte in cell 1 with a comparative cell 1 made with LiTFSI as the salt.

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.

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

In the context of the present invention, a chemical bond is not drawn on an atom, but on a position where it intersects the bond, e.g. on the surface of a metal

Represents any H on cyclohexane may be substituted by a substituent R₀₄And two or more H can be replaced by one H, and the substituents can be the same or different. If a certain C of cyclohexane contains two H, the two H may be substituted by all substituents or only 1, for example both H may be substituted by methyl, or one may be substituted by methyl and one by ethyl. In addition, substituents may also be attached to the ring via a double bond. For example, in this structure, if R₀₄Is methyl, ═ O, F, the structure can be

In the structural formulae of the present invention, when a group in the parentheses "()" is contained after a certain atom, it means that the group in the parentheses is connected to the atom before it. Such as-C (CH)₃)₂-is of

-CH(CH₃) -is of

In the title and description of the invention, -NBF₃M in M may be a monovalent, divalent, trivalent or polyvalent metal cation, or-NBF if it is a non-monovalent ion₃The number of (c) is increased correspondingly so that it exactly matches the valence of M.

In the specific structural formula shown in the claims of the invention, only one substituent is drawn on each C to indicate that H on the C can be partially substituted or fully substituted. For example in the structural formula

In, R₁、R₂Both indicate that it may replace one or both of the H's on the C.

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

In the title and description of the present invention, the expressions "structure provided by the present invention", "nitrogen-based boron trifluoride salt", "nitrogen-based boron trifluoride organic salt", "five-membered ring nitrogen-based salt", "boron trifluoride salt", "nitrogen-based boron trifluoride compound", and the like are different, but all refer to the structure provided by the present invention.

The invention provides a monobasic organic boron trifluoride salt which can be used as an electrolyte additive and an electrolyte salt, namely, the monobasic organic boron trifluoride salt contains-NBF in the organic matter₃M 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, -NH in the raw material participates in the reaction, and other structures do not participate in the reaction. The specific preparation method mainly comprises two steps:

adding an M source and a raw material into a solvent under the atmosphere of nitrogen/argon, mixing, reacting at 5-60 ℃ for 5-24 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 5-24 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, cyclohexane, diphenyl ether, etc.

Example 1

Starting materials

The preparation method comprises the following steps: 0.02mol of the starting material and boron trifluoride tetrahydrofuran complex (2.8g, 0.02mol) were mixed uniformly in 15ml of ethylene glycol dimethyl ether in 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 (1.04g, 0.02mol) in 10ml ethanol, slowly adding the mixture into the intermediate, stirring at 45 ℃ for reaction for 8 hours, drying the obtained mixed solution under reduced pressure at 45 ℃ and under the vacuum degree of-0.1 MPa, washing the obtained solid with n-butyl ether three times, filtering and drying to obtain a product P1. The yield of the product P1 was 89%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 1.

Example 2

Raw materials

The preparation method comprises the following steps: 0.02mol of the starting material and boron trifluoride diethyl etherate (2.98g, 0.021mol) were mixed uniformly in 15ml of THF (tetrahydrofuran) under an argon atmosphere, and reacted at room temperature for 18 hours. The obtained mixed solution is decompressed and dried at 50 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. 13ml of butyllithium in hexane (c 1.6mol/L) was added to the intermediate, the reaction was stirred at room temperature for 6 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 83%.

Example 3

Raw materials

The preparation method comprises the following steps: 0.02mol of the starting material and lithium methoxide (0.76g,0.02mol) were mixed uniformly with 20ml of methanol under a nitrogen atmosphere, and reacted at room temperature for 24 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. Boron trifluoride tetrahydrofuran complex (3.07g, 0.022mol) and 15ml THF (tetrahydrofuran) were added to the intermediate, stirred at room temperature for reaction for 16 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 the product P3 was 84%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 2.

Example 4

Raw materials

The preparation method comprises the following steps: in a glove box, 0.02mol of the starting material and boron trifluoride diethyl etherate (2.98g, 0.02mol) were mixed uniformly in 15ml of ethylene glycol dimethyl ether, and reacted at room temperature for 12 hours. The obtained mixed solution is decompressed and dried at the temperature of 45 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. Dissolving lithium ethoxide (1.04g, 0.02mol) in 10ml ethanol, adding the mixture into the intermediate, stirring at room temperature for reaction for 6 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 84%.

Example 5

Raw materials

The preparation method comprises the following steps: 0.02mol of the starting material and boron trifluoride acetic acid complex (3.83g, 0.0204mol) 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 50 ℃ and a vacuum degree of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Sodium acetate (1.64g, 0.02mol) is dissolved in 10ml of N, N-dimethylformamide and added into the intermediate, the mixture is stirred and reacted for 8 hours at 50 ℃, the obtained mixed solution is decompressed and dried at 80 ℃ and the vacuum degree of about-0.1 MPa, the obtained solid is washed three times by diphenyl ether, and the product P5 is obtained after filtration and drying. The yield of product P5 was 89%.

Example 6

Starting materials

P6 provided in this example was prepared from 0.02mol of starting material by the method of example 1, and the yield was 85%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 3.

Example 7

Raw materials

P7 was prepared from 0.02mol of the starting material in the same manner as in example 2, and was found to have a yield of 87%.

Example 8

Starting materials

P8 was prepared from 0.02mol of the starting material in the same manner as in example 3, and had a yield of 89%.

Example 9

Raw materials

P9, provided in this example, was prepared from 0.02mol of starting material by the method of example 4 with a yield of 86%.

Example 10

Raw materials

P10, provided in this example, was prepared from 0.02mol of starting material by the method of example 3 with a yield of 87%.

Example 11

Raw materials

P11, provided in this example, was prepared from 0.02mol of starting material by the method of example 2 with a yield of 84%.

Example 12

Starting materials

P12, provided in this example, was prepared from 0.02mol of starting material by the method of example 1 with a yield of 86%.

Example 13

Raw materials

P13 provided in this example was prepared from 0.02mol of starting material by the method of example 2, and the yield was 89%, and the nuclear magnetic hydrogen spectrum is shown in FIG. 4.

Example 14

Raw materials

P14, provided in this example, was prepared from 0.02mol of starting material by the method of example 3 with a yield of 87%.

Example 15

The nitrogen-based boron trifluoride organic salt protected by the invention is mainly used as an additive and a salt in a battery (including a liquid battery and a solid battery), the additive mainly plays a role in generating a passivation layer, and ions can be dissociated per se to play a role in supplementing consumed 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; the salt serving as electrolyte mainly plays a role of providing ion transmission and passivating an electrode, and is independently used as salt or matched with the traditional salt to be used as double salt, so that the effect is good. The performance of the invention is illustrated in experimental manner below.

As 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_0.05O₂NCA for short), lithium nickel manganese oxide (LiNi)_0.5Mn_1.5O₄Abbreviated LNMO), Na_0.9[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 table

Battery positive and negative electrode system	Positive electrode main material	Cathode 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 electrolytes P1-P14, and uniformly mixing organic solvents, conventional salts and conventional additives to obtain series electrolytes E1-E14, wherein the solvents used in the method are Ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), Ethylene Carbonate (EC) and Propylene Carbonate (PC). Functional additives (i.e., conventional additives) are fluoroethylene carbonate (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 liquid electrolyte E formulated with structure P provided by the invention as an additive

Note: 1M means 1 mol/L.

Comparison sample: replacing P1-P14 with blanks according to the proportion of E1-E14 (namely, not adding P1-P14), and obtaining corresponding conventional liquid electrolyte reference samples L1-L14.

(4) Button cell assembly

The liquid electrolyte series E1-E14 containing the structure of the embodiment as an additive and the conventional liquid electrolytes L1-L14 are assembled into a button cell in a comparative way, and the details are as follows: negative electrode shell, negative electrode pole piece, PE/Al₂O₃The diaphragm, electrolyte, positive pole piece, stainless steel sheet, spring piece and positive shell are assembled into button cellPerforming a long-cycle test at a temperature, wherein the cycle mode is 0.1C/0.1C1 cycle, 0.2C/0.2C5 cycle and 1C/1C44 cycle (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 commercial Al₂O₃a/PE porous separator.

The battery systems prepared from E1-E14 are batteries 1-14, respectively, and the battery systems prepared from L1-L14 are comparative batteries 1-14, 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 14 and the comparative batteries 1 to 14 at room temperature are shown in table 4.

Table 3 configuration and test mode for example and comparative batteries

Table 4 comparison of test results for example cells and comparative cells

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 first-cycle discharge specific capacity and the capacity retention rate of the battery using the structure P1-P14 as the liquid electrolyte additive are much better than those of the battery without the 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 liquid electrolytes

(1) Preparing liquid electrolyte

The series of liquid electrolytes R1, R3, R6 and R10 are obtained by uniformly mixing the P1, P3, P6 and P10 with an organic solvent, a conventional additive and a conventional salt, the series of conventional liquid electrolytes Q1, Q3, Q6 and Q10 are obtained by uniformly mixing the conventional salt, the organic solvent and the conventional additive, and the used solvent and the functional additive comprise the solvent and the functional additive which are described in the 'one' in the embodiment. The specific components and ratios of the liquid electrolyte are shown in table 5.

Table 5 Synthesis of substance P as a liquid electrolyte formulated with salt

(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

1,3, 6, and 10, and 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 higher, 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-cycle efficiency, the first-cycle specific discharge 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

In the environment with the dew point lower than minus 60 ℃, the structure, the polymer and the inorganic filler provided by the invention are dissolved in DMF according to the proportion, and polymer electrolyte membranes G1, G2, G6, G13 and polymer comparative electrolyte membranes G '1-G' 2 are obtained after stirring, mixing, coating, film forming, rolling and drying. The specific components and ratios are shown in Table 8. The polymer is polyethylene oxide (PEO, molecular weight is 100 ten thousand), the inorganic filler is LLZO of 160nm, namely Li with crystal form of cubic phase and median particle size of 160nm₇La₃Zr₂O₁₂An inorganic oxide solid electrolyte.

TABLE 8 concrete composition and compounding ratio of Polymer electrolyte Membrane

Polymer electrolyte membrane	Polymer and method of making same	Salt (salt)	Inorganic filler	The former mass ratio	Solvent(s)
						G1	PEO100 ten thousand	P1	160nmLLZO	4.2：1：0.8	DMF
G2	PEO100 ten thousand	P2	/	4.2：1	DMF
						G6	PEO100 ten thousand	P6	160nmLLZO	4.2：1：0.8	DMF
G13	PEO100 ten thousand	P13	/	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 90: 5:2.5:2.5 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) and lithium nickel manganese cobalt oxide (NCM811 for short) were selected as the active materials, SuperP was used as the electron conductive additive, polyvinylidene fluoride (PVDF) was used as the binder, and NMP was used as the solvent.

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

(3) Battery assembly and testing

And (3) cutting the polymer electrolyte membrane and the positive and negative pole pieces, assembling into the 1Ah all-solid-state soft package battery, and carrying out 50-DEG C long cycle test on the battery in the cycle modes of 0.1C/0.1C2 cycle and 0.3/0.3C48 cycle. 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 batteries of examples and comparative batteries

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

Example and comparative batteries	First week discharge capacity (Ah))	First week efficiency (%)	Capacity retention (%) at 50 weeks of circulation
				Battery
1	0.89	89.3	85.5
				Battery 2	0.90	90.1	85.1
Battery 6	0.87	87.2	87.2
				Battery 13	0.85	85.6	87.4
Comparative battery 1	0.88	88.3	67.6
				Comparative battery 2	0.85	85.5	68.7

From the data in tables 9 and 10, it can be seen that the batteries prepared from P1, P2, P6 and P13 have excellent long-cycle stability and superior performance to that of the battery corresponding to LiTFSI, probably because the nitrogen-based boron trifluoride salt of the present invention not only has excellent ion transport performance, but also can form a more dense and stable passivation layer on the surface of the positive electrode to prevent the catalytic decomposition of the positive electrode active material on the components of the electrolyte, and in addition, the boron trifluoride salt of the present invention does not corrode the current collector, thus exhibiting superior performance to that of the conventional salt.

In addition, the application also selects some nitrogen-based boron trifluoride salts as additives and shows the effect diagrams of the salt examples. FIGS. 5-8 are graphs comparing the performance of battery 1/2/5/13 made with example 1/2/5/13 as an electrolyte additive to a corresponding comparative battery 1/2/5/13 that did not contain example 1/2/5/13 of the present invention. FIGS. 9-10 are graphs comparing the effect of the battery 1/3 made from the liquid electrolyte salt of example 1/3 with a corresponding comparative battery 1/3 that did not contain the inventive example 1/3. Fig. 11 is a graph comparing the effects of example 1 as a battery 1 made of salt in solid electrolyte with a comparative battery 1 made of LiTFSI as salt. It can be seen from FIGS. 5-11 that the structure of the present invention has excellent effects.

The first-cycle efficiency, the first-cycle specific discharge capacity, the first-cycle discharge capacity, the capacity retention rate and other properties have direct and significant influences 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 previous experimental data, the data are surprisingly found to be greatly improved compared with the conventional data, particularly the performance of the liquid electrolyte additive is improved by about 5-30%, and the additive and the conventional additive in the application also show better effect. 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, no matter the nitrogen-based boron trifluoride compound is used as an additive or a salt, the nitrogen-based boron trifluoride compound not only can be applied to a liquid battery, but also can be applied to a solid battery, and has extremely excellent effect and 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 a word, the nitrogen-based boron trifluoride salt provided by the application can be used in a small amount in an electrolyte, and mainly has the effects that a passivation layer is formed on the surface of an electrode after decomposition, and ions capable of being dissociated are contained in the passivation layer, so that the ions provided by the electrode are less consumed in the process of forming the passivation layer, and the first cycle efficiency and the cycle performance of a battery are obviously improved; the use amount of the electrolyte can be increased to be used as electrolyte salt, the electrolyte salt is mainly used for transmitting ions after dissociation, the passivation electrode is used as a secondary function, and the electrolyte salt is independently used as salt or is matched with the traditional salt to be used as double salt and has better electrochemical performance. The nitrogen-based 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 improving the energy density, the cycling stability and the service life of the batteries. And the raw materials are low in price, and the synthesis and purification processes are simple, so that the method has good economic benefits.

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:

all the effects are excellent, and other structures similar to the structures recorded in any section of the application also have better effectsFor reasons of space, however, the effect of the structure protected by the present invention will now be described only by way of examples 1 to 14. In examples 1 to 14 and the preparation methods of the above-listed structures, all of which are methods in which a raw material, an M source and a boron trifluoride compound are reacted to obtain a boron trifluoride organic salt as a product, i.e., the-NH in the raw material is changed to-NBF₃M, 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 also 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 should 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 a five-membered cyclic nitrogen-based salt structure, wherein the electrolyte comprises a boron trifluoride salt, and the structure of the boron trifluoride salt is shown as general formula I:

wherein M is a metal cation;

R₁、R₂、R₃、R₄is a carbon atom or a heteroatom selected from S, N, O, P, Se, Ca, Al, B or Si;

R₅as a substituent, any one H on the representative ring can be independently substituted by a substituent, and the substituent replaces one H or two H, and in the case where the substituent replaces two H, each substituent is the same or different.

2. The electrolyte of claim 1, wherein N and R are₁And N and R₄Are connected by a single bond, R₁And R₂R is₂And R₃R is₃And R₄Are connected by single or double bonds.

3. The electrolyte of claim 1, wherein the substituent is selected from the group consisting of a chain-type substituent, a ring-type substituent, a salt-type substituent, and a group in which H, which is bonded to a C atom, of any one or more of these groups is substituted with a halogen atom.

4. The electrolyte of claim 3, wherein the chain-type substituent is selected from H, a halogen atom, a carbonyl group, an ester group, an aldehyde group, an ether oxy group, an ether thio group, O, S, and S,

Nitro, cyano, amide, primary amine, tertiary amine, secondary amine, sulfonamide, sulfoalkane, hydrazino, diazo, hydrocarbyl, heterohydrocarbyl;

wherein R is₁₁And R₁₂Independently is H or a hydrocarbyl group; ester groups include carboxylic acid esters, carbonic acid esters, sulfonic acid esters, and phosphoric acid esters; hydrocarbyl groups include alkyl, alkenyl, alkynyl, and alkenylalkynyl groups; a heterohydrocarbyl group is a hydrocarbyl group containing at least one heteroatom; the heteroatoms in the heterohydrocarbyl group are selected from halogen, N, P, S, O, Se, Al, B, and Si;

the ring substituent comprises a ternary-eight-membered ring and a polycyclic ring formed by at least two monocyclic rings;

preferably, the carbonyl group is

The ester group is-R₁₃COOR₁₄、-R₁₃OCOR₁₄、-R₁₃SO₂OR₁₄、-R₁₃O-CO-OR₁₄Or

Amide is

Sulfonamide group of

The sulfoalkane is

Diazo is-N ═ N-R₁₆With an ether oxygen radical of-R₁₃OR₁₄The etherthio radical is-R₁₃SR₁₄(ii) a Wherein R is₁₃、R₁₄、R₁₅、R₁₆、R₁₇、R₁₈、R₁₉Independently is an alkyl, alkenyl, alkynyl or alkenynyl group or heterohydrocarbyl group having from 1 to 20 carbon atoms which includes alkyl, alkenyl, alkynyl or alkenynyl groups and which includes heteroalkyl, heteroalkenyl or heteroalkynyl groups, with substituents optionally attached to the rings; r directly linked to N₁₆、R₁₇、R₁₈、R₁₉The radicals can also be H or a metal ion, R being directly bonded to O₁₁、R₁₂、R₁₃The group can also be a metal ion.

5. The electrolyte of claim 4,R₁、R₄is a carbon atom, and R₁、R₄Attached substituent R₅Is ═ O.

6. The electrolyte of any one of claims 1-5, wherein M in formula I comprises Na⁺、K⁺、Li⁺、Mg²⁺Or Ca²⁺Preferably Na⁺、K⁺Or Li⁺；

7. A method for producing an electrolyte containing a five-membered cyclic nitrogen-based salt structure according to any one of claims 1 to 6, wherein the nitrogen-based salt is obtained by reacting a starting material containing-NH with a boron trifluoride-based compound and an M source.

8. Use of the electrolyte containing a five-membered cyclic nitrogen-based salt structure according to any one of claims 1 to 6 in a secondary battery, wherein the use is: the boron trifluoride salts can be used both as additives and as salts for electrolytes.

9. The use according to claim 8, wherein the use comprises use in a liquid electrolyte, a gel electrolyte, a mixed solid-liquid electrolyte, a quasi-solid electrolyte, an all-solid electrolyte, each independently comprising an electrolyte comprising a nitrogen-based salt structure according to any one of claims 1 to 6.

10. The use according to claim 9, further comprising use as a battery or battery pack, the battery comprising the electrolyte containing a nitrogen-based salt structure of any one of claims 1-6, and a positive electrode, a negative electrode and a packaging casing, the electrolyte being applicable to liquid batteries, hybrid solid-liquid batteries, semi-solid batteries, gel batteries, quasi-solid batteries and all-solid batteries; the battery pack includes the battery.