CN114243107A

CN114243107A - Unsaturated carbon chain electrolyte and preparation and application thereof

Info

Publication number: CN114243107A
Application number: CN202010943378.0A
Authority: CN
Inventors: 俞会根; 杨萌
Original assignee: Beijing WeLion New Energy Technology Co ltd
Current assignee: Beijing WeLion New Energy Technology Co ltd
Priority date: 2020-09-09
Filing date: 2020-09-09
Publication date: 2022-03-25

Abstract

The invention relates to an unsaturated carbon chain electrolyte, and preparation and application thereof, wherein the electrolyte comprises a boron trifluoride salt represented by the following general formula I: in the general formula I, R or R₁Independently a first chain without or containing at least one atom; and R₁Is not absent at the same time; r₂、R₃Independently a second chain free or containing at least one atom; m is a metal cation; the first chain and the second chain are both carbon chains; 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; at least one of the first chain, the second chain and the chain substituentContaining one unsaturated bond. The electrolyte in the present application creatively combines two-OBF₃M is compounded in a compound, which can be used as electrolyte salt, additive and polymerization monomer with good effect.

Description

Unsaturated carbon chain electrolyte and preparation and application thereof

Technical Field

The invention relates to the technical field of batteries, in particular to an unsaturated carbon chain electrolyte and preparation and application thereof.

Background

The electrolyte is an important and necessary component of the secondary battery, the lithium/sodium battery has the advantages of high energy density, high voltage, multiple cycle times, long storage time and the like, and since commercialization, the lithium/sodium battery is widely applied to various aspects such as electric vehicles, energy storage power stations, unmanned aerial vehicles, portable equipment and the like, and no matter which application direction, the energy density and the cycle performance of the battery are urgently required to be improved on the premise of ensuring the safety of the battery.

The lithium/sodium battery mainly comprises a positive electrode, a negative electrode, an electrolyte and a diaphragm, and the improvement of the energy density of the battery is to improve the working voltage and the discharge capacity of the battery, namely to use a high-voltage high-capacity positive electrode material and a low-voltage high-capacity negative electrode material; the improvement of the cycle performance of the battery is mainly to improve the stability of an interface layer formed between an electrolyte and a positive electrode and a negative electrode.

Taking a lithium battery as an example, in the current lithium battery, commonly used positive electrode materials include high voltage Lithium Cobaltate (LCO), high nickel ternary (NCM811, NCM622, NCM532, and NCA), Lithium Nickel Manganese Oxide (LNMO), lithium rich (Li-rich), and the like; common negative electrode materials include metallic lithium, graphite, silicon carbon, silicon oxycarbide, and the like; the commonly used separator is mainly a porous film of polyethylene or polypropylene. The electrolyte comprises a liquid electrolyte and a solid electrolyte, wherein the liquid electrolyte is a mixture of lithium salt and a non-aqueous solvent and is divided into a carbonate electrolyte and an ether electrolyte according to the type of the solvent; the solid electrolyte mainly comprises a polymer electrolyte, an inorganic oxide electrolyte and a sulfide electrolyte. The sulfide electrolyte is extremely sensitive to air, has a narrow electrochemical window and is unstable to the anode; the oxide electrolyte has too high hardness and high brittleness; the electrochemical window of the polymer electrolyte is not wide, the conductivity is low, and the ion transference number is low. Therefore, most of the currently used electrolytes are liquid electrolytes, and a few of them use polymer electrolytes. The development of the single-ion conductor polymer electrolyte with higher conductivity, wide electrochemical window and high ion migration number is particularly important. In addition, when the high-voltage anode and the low-voltage cathode are matched with a conventional liquid electrolyte, part of lithium ions coming out of the anode are consumed in the first cycle, and a passivation layer which only conducts ions and does not conduct electrons is formed on the surfaces of the anode particles and the cathode particles. Sodium ion batteries also suffer from similar problems.

Additives such as fluoroethylene carbonate and vinylene carbonate are often added into the electrolyte to improve the battery performance, but the conventional electrolyte additives usually do not contain dissociable ions and only consume ions of the positive electrode to form a surface passivation layer, so that the first-effect and specific discharge capacity are low. If the added salt/additive can form a passivation layer which is conductive to ions and good in stability on the surface of the electrode, the liquid electrolyte and the polymer electrolyte with narrow electrochemical windows can be applied to a high-voltage battery system. In addition, the price of the lithium/sodium salt which is commercially available at present is very high, so that the cost of the whole battery is higher, and if a new lithium/sodium salt or other salts which replace the lithium/sodium salt in the prior art can achieve both high performance and low cost, the price of the battery is necessarily greatly reduced.

One of the groups of the Applicant has been working on compositions containing-OBF obtained by substitution of one hydroxyl group-OH₃Compounds of the M group were studied. Due to-OBF₃Is a strongly polar group capable of forming a salt structure with a cation, thus, -OBF₃M has a strong sense of presence in one molecular structure, which may change the properties of the entire molecular structure. In the prior art, only a few researchers have sporadically studied compounds containing a BF3 group, and all have conducted only one BF₃The group is researched, at present, no great results are obtained, and no results of industrial application are found; the prior art is directed to-O-BF₃M groups were studied, not to mention the two-OBF groups₃Studies of the M group are published. This is also because-OBF₃M is strongly present, if-OBF is added to the molecule₃The number of M may vary unpredictably in the overall properties of the overall molecular structure, and thus research teams may be able to conduct procedures involving two or more-OBFs₃M research shows that the resistance is greatly increasedAdditionally, the time and economic costs that may be incurred are extremely large, and the results are not well predictable, so that the research team has been on the basis of having only one-OBF₃M was studied. Even if the pair contains one-OBF₃M is researched, and due to the fact that the prior art is few, the reference value is small, and the research on two groups is not from any reference source. The present research team also unexpectedly found-OBF containing a dihydroxy substitution in occasional studies₃M organic matter is applied to lithium/sodium batteries in liquid electrolyte and solid electrolyte, and the prepared batteries have excellent performance and surprising effect through tests, so that a specially established team carries out special research on double-substituted-OBF₃M, and obtains better research results.

More importantly, the present application is directed to-OBF₃Independent studies of the structure of the type in which M is attached to an unsaturated carbon chain, i.e. two-OBF₃M is linked to the unsaturated carbon chain. This is because the unsaturated carbon chain contains unsaturated bonds, and the electrical and chemical properties of the unsaturated carbon chain are relatively specific and self-integrated, and the two strongly polar-OBFs₃M, when attached to an unsaturated carbon chain, also affects the chemical and physical properties of the entire chain, where it is substantially different from rings and heterochains, and so on, and therefore the relationship or deductibility between them is uncertain. Thus, the linkage of-OBF to the unsaturated carbon chain₃M, it may have effects different from those of other structures, especially the connection of two-OBFs₃M, it may have a more unexpected superior effect. The present application therefore identifies the subject as having two-O-BF attached to an unsaturated carbon chain₃M, thereby more specifically determining-O-BF₃Specific cases where M is attached to an unsaturated carbon chain.

Disclosure of Invention

The invention provides an unsaturated carbon chain electrolyte, and preparation and application thereof, aiming at overcoming the defects in the prior art.

The purpose of the invention is realized by the following technical scheme:

an aspect of the present invention provides an unsaturated carbon chain-based electrolyte including an unsaturated carbon chain-based boron trifluoride salt represented by the following general formula I:

in the above formula I, R or R₁Independently a first chain without or containing at least one atom; and R₁Is not absent at the same time; r₂、R₃Independently a second chain free or containing at least one atom; m is a metal cation; and-OBF₃The atom to which M is attached is a carbon atom C; the first chain and the second chain are both carbon chains; 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, the second chain and the chain substituent group at least contain one unsaturated bond, and the unsaturated bond comprises a carbon-carbon double bond or a carbon-carbon triple bond.

Preferably, in formula I, R₂、R₃Independently a carbon chain of 0-5 atoms; r, R₁Independently a carbon chain of 1 to 25 atoms.

Preferably, the main chain in the structure of the general formula I is a chain with the length of 1-25 carbon atoms; r₂、R₃Independently a carbon chain of 0-3 atoms.

Preferably, the chain substituents are selected from alkyl, alkenyl, alkynyl, alkenylalkynyl, alkynyl, and the like,

Or a salt substituent. 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 may be optionally bonded to a first substituent. The first substituent is selected from

From H, halogen atom, carbonyl, ester group, aldehyde group, ether oxygen group, ether sulfur group, ═ O, ═ S, and,

Nitro, cyano, amino, amide, sulfonamide, sulfoalkane, hydrazino, diazo, alkyl, heteroalkyl, cyclic substituents, salt substituents, and any of these groups wherein hydrogen H is substituted with a halogen atom; the hydrocarbon group comprises alkyl, alkenyl, alkynyl and alkenylalkynyl, and the heterohydrocarbon group is a hydrocarbon group containing at least one heteroatom; the heteroatom is selected from halogen, S, N, O, P, Se, Ca, Al, B or Si. Wherein R is₅、R₆Independently is H, alkyl, alkenyl or alkynyl, R₂、R₃Independently is H, hydrocarbyl or heterohydrocarbyl; such salt substituents include, but are not limited to, sulfate (e.g., lithium sulfate, sodium sulfate, potassium sulfate), sulfonate (e.g., lithium sulfonate), sulfonimide salt (e.g., lithium sulfonimide), carbonate, carboxylate (e.g., lithium carboxylate, sodium, potassium, etc.), thioether salt (e.g., -SLi), oxoether salt (e.g., -OLi), ammonium salt (e.g., -NLi), hydrochloride, nitrate, azide, silicate, phosphate.

Preferably, formula I comprises: (1) r₂And R₃All are absent, R and R₁Independently a first chain containing at least one C atom, noted

two-OBF₃M is linked to R and R, respectively₁On any one of the C atoms; (2) r₁、R₂And R₃Both are absent, R is a first chain containing at least one C atom, two-OBF₃M is linked to the same C, denoted

(3) R and R₁Independently a first chain containing at least one C atom, R₂And R₃Independently a second chain of no or 1 to 4 carbon atoms C, and not both simultaneously absent, is designated

The R, R₁、R₂Or R₃Can have the substituent attached thereto.

Preferably, for said formula i, the structure can be any one of the following:

wherein Q is₁、Q₂represents-OBF₃M; z in each structure₀～Z₁₈Are each independently selected from the class defined in any of the substituents described in any one of the preceding paragraphs.

Preferably, in the formula I, Z in each structure₀～Z₁₈Are each independently selected from a second substituent selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, ethenyl, propenyl, ethynyl, propynyl, ═ CH₂、＝CHCH₃、＝CHCH₂CH₃Or a cyclic substituent; the cyclic substituent comprises cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or polycyclic, preferably the cyclic substituent comprises phenyl, pyridine, cyclohexane, cyclohexenyl, pyran, cyclopentanyl, cyclopentenyl, furan, pyrrole, thiophene or polycycle

The cyclic substituent may be optionally bonded with a first substituent, and preferably, the first substituent is an alkyl group, an alkenyl group, an alkynyl group, an ester group, a carbonyl group, an oxy group, an ═ O, an ═ S, an ═ CH₂Alkylthio, cyano, nitro, amino, ether or halogen.

Preferably, the second substituent is selected from H, methyl, ethyl, propyl, isopropyl, butyl, ethenyl, ethynyl, ═ CH₂、＝CHCH₃Or a cyclic substituent; the cyclic substituent is selected from phenyl, pyridine, thiophene or

The first substituent is selected from H, alkyl, halogen atom, nitro, aldehyde group, halogenated alkyl, sulfonyl or alkoxy. And a second substituent Z attached to the last carbon atom (refer to Z as described above)_0-18) Preferably H or methyl.

Preferably, the formula I is a lithium, potassium, sodium, calcium or magnesium salt, i.e. M in formula I comprises Na⁺、K⁺、Li⁺、Mg²⁺Or Ca²⁺Preferably a lithium, potassium or sodium salt.

Another aspect of the present invention is to provide a method for preparing the electrolyte according to any one of the above paragraphs, the method comprising: the unsaturated carbon chain binary structure containing two-OH groups, the boron trifluoride compound and an M source (such as M salt, M base or other substances capable of providing a metal cation M for the general formula I of the application) react to obtain a product, namely the unsaturated carbon chain boron trifluoride structure containing two-OBF 3M groups.

The invention also provides an additive applied to a lithium/sodium battery, which comprises the unsaturated carbon chain type boron trifluoride represented by the general formula I.

The invention also provides a lithium/sodium salt applied to a lithium/sodium battery, wherein the lithium/sodium salt comprises unsaturated carbon chain type boron trifluoride represented by the general formula I. The lithium/sodium salts include lithium/sodium salts in liquid electrolytes and in solid electrolytes.

It is a further aspect of the present invention to provide an electrolyte comprising a liquid electrolyte, a solid electrolyte, an electrolyte composite membrane or a gel electrolyte, the electrolyte comprising the electrolyte described in any of the above paragraphs.

The invention also provides a battery, which comprises a liquid battery, a solid-liquid mixed battery or a gel battery; the battery comprises the unsaturated carbon chain electrolyte, a positive electrode, a negative electrode, a diaphragm and a packaging shell.

A final aspect of the present invention is to provide a battery pack including the battery.

The invention has the following main beneficial effects:

the electrolyte in the present application creatively combines two-OBF₃M is complexed in one compound, and is preferably-OBF₃M is bonded to the carbon atom C. The boron organic compound can be used as an additive in liquid or solid electrolyte, can form a stable and compact passivation film on the surface of an electrode of a lithium/sodium battery, prevents the direct contact of electrolyte and the electrode, inhibits the decomposition of the electrolyte, and can remarkably improve the cycle performance, the discharge specific capacity and the charge-discharge efficiency of the lithium/sodium battery; in addition, the boron organic compound additive is a lithium/sodium ion conductor, and as the additive, a passivation layer formed on the surface of an electrode rarely consumes lithium/sodium ions extracted from the anode during film formation, so that 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 assembled into a lithium/sodium 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, the double additives, and the battery using the double additives shows more excellent electrochemical performance.

More importantly, the present application contains 2-OBF₃The boron organic compound of M can be used as a salt in an electrolyte, and more surprisingly, the boron organic compound can also be used as a salt in an all-solid-state battery, which is safer, lithium/sodium ions containing boron in the non-aqueous solvent of the application are easily solvated, higher ionic conductivity is provided for the battery, and the defects of lithium/sodium salts in the traditional electrolyte can be overcome, namely the solid electrolyte containing the boron organic compound salt has the advantages of no corrosion to a current collector and high voltage resistance, and the PEO with a narrow electrochemical window can be matched with a high-voltage (more than 3.9V) positive electrode, so that the electrochemical performance of the lithium/sodium battery is obviously improved. Moreover, the salt in the application can be combined with the traditional lithium/sodium salt as a double salt, and the effect is also good. Furthermore, the structure in the present application is used in the electrolyte, itself as an additionThe properties of the agent and the properties of the salt can also act synergistically, so that the lithium ion battery has excellent effects superior to those of the conventional additive or lithium/sodium salt, for example, when the lithium ion battery is used as a lithium salt, the lithium ion battery not only has better ion transmission, but also can form a stable passivation layer on the surface of an electrode in the battery cycling process to prevent PEO or other components from being further decomposed, and therefore, the battery shows more excellent long-cycle stability.

The polymer electrolyte can be used as a polymeric monomer in a polymer electrolyte, and in a polymer electrolyte battery, the polymer electrolyte has the properties and the effects of lithium/sodium salt while being used as a polymeric monomer, so that the polymer electrolyte polymerized as a monomer by the polymer electrolyte still has excellent effects under the condition of not adding the lithium/sodium salt, and after the conventional lithium/sodium salt is additionally added, the battery shows more excellent electrochemical performance due to the fact that the quantity of dissociated ions is increased. Thus, the present application contains 2-OBFs₃When the structure of M is used, multiple effects of M can be used for realizing synergistic effect, and the effect is good and the significance is great.

In addition, the boron organic compound has the advantages of rich raw material sources, wide raw material selectivity, low cost, simple preparation process, mild reaction conditions and excellent industrial application prospect, and only needs to react a compound containing two-OH groups with boron trifluoride organic compounds and an M source (M is a metal cation).

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.

Drawings

FIGS. 1 to 14 are nuclear magnetic hydrogen spectra of products shown in examples 1 to 14 of the present invention, respectively;

FIGS. 15-18 are graphs illustrating the cycling effect of the electrolyte additive of the present application;

FIGS. 19-20 are graphs illustrating the cycling effect of lithium salts as electrolytes in the present application;

fig. 21 and 22 are graphs illustrating the cycling effect of the present application as a single ion polymer electrolyte.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention, and it is obvious that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

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, -OBF₃M in M may be a monovalent, divalent, trivalent or polyvalent metal cation, if it is not a monovalent ion, -OBF₃The number of (c) is increased correspondingly so that it exactly matches the valence of M.

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

The invention provides a binary organic boron trifluoride salt which can be used as an electrolyte additive, an electrolyte lithium/sodium salt and a polymerization monomer in a polymer electrolyte at the same time, namely, the binary organic boron trifluoride salt contains two-OBF in the organic matter₃M is a group in which M is Li⁺Or Na⁺And the like. The binary boron trifluoride salt can be applied to liquid batteries, and can also be excellently applied to gel batteries and 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, -OH 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 under the atmosphere of nitrogen/argon, mixing, reacting at 5-45 ℃ for 1-12 hours, and drying the obtained mixed solution under reduced pressure at 0-50 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent to obtain an intermediate; adding boron trifluoride compounds, stirring and reacting at 5-50 ℃ for 6-24 hours, drying the obtained mixed solution under reduced pressure at 30-80 ℃ 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 a final product, namely the binary organic boron trifluoride salt, wherein the yield is 74-95%.

Secondly, under the atmosphere of nitrogen/argon, adding the raw materials and boron trifluoride compounds into a solvent, uniformly mixing, reacting for 12 hours at the temperature of 5-40 ℃, drying the obtained mixed solution under reduced pressure at the temperature of 0-40 ℃ 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 6-8 hours at 5-50 ℃ to obtain a crude product, directly washing the crude product or washing the crude product after drying under reduced pressure, and then filtering and drying to obtain a final product, namely the binary organic boron trifluoride salt, wherein the yield is 74-95%.

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 raw materials can be simultaneously used as the solvent), ethyl acetate, DMF, acetone, hexane, dichloro, tetrahydrofuran, glycol dimethyl ether and the like. The washing may be carried out with diethyl ether, n-butyl ether, cyclohexane, diphenyl ether, etc.

Example 1: raw materials

The preparation method comprises the following steps: 1, 2-dihydroxyethylene (0.6g, 0.01mol) and boron trifluoride tetrahydrofuran complex (2.8g, 0.02mol) as raw materials 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 30 ℃ 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 M1. The yield was 78%, and the nuclear magnetization is shown in FIG. 1.

Example 2: raw materials

The preparation method comprises the following steps: a lithium metal plate (0.7g, 0.1mol) was slowly added to 2-hydroxyallyl alcohol (3.7g, 0.05mol) under an argon atmosphere, reacted at room temperature for 4 hours, and then warmed to 50 ℃ until the lithium plate reaction was complete to give an intermediate. Adding boron trifluoride butyl ether complex (3.96g, 0.02mol) into the intermediate, stirring and reacting for 6 hours at 30 ℃, 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 for three times, filtering and drying to obtain the product M2. The yield was 75%, and the nuclear magnetization is shown in FIG. 2.

Example 3: raw materials

The preparation method comprises the following steps: under argon atmosphere, maleic-1, 4-diol (0.88g, 0.01mol) and boron trifluoride diethyl etherate (2.98g,0.021mol) as raw materials were mixed uniformly in 15ml of THF, 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. 14ml 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 M3. The yield was 83%, and the nuclear magnetization is shown in FIG. 3.

Example 4: raw materials

The preparation method comprises the following steps: 1, 5-hexadiene-3, 4-diol (1.14g, 0.01mol) and lithium methoxide (0.76g,0.02mol) were taken as raw materials and mixed uniformly with 25ml of methanol under a nitrogen atmosphere, followed by reaction at room temperature for 8 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) is added into the intermediate, stirred and reacted for 6 hours at room temperature, the obtained mixed solution is decompressed and dried at 40 ℃ and the vacuum degree of about-0.1 MPa, the obtained solid is washed three times by isopropyl ether, and the product M4 is obtained after filtration and drying. Yield 81%, nuclear magnetization is shown in figure 4.

Example 5: raw materials

The preparation method comprises the following steps: the starting material (2E) -2-hexene-2, 5-diol (1.16g, 0.01mol) and boron trifluoride acetic acid complex (3.83g, 0.0204mol) were mixed uniformly in 15ml of THF under an argon atmosphere, reacted at 40 ℃ for 12 hours, and the resulting mixed solution was dried under reduced pressure at 40 ℃ and a vacuum degree of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Sodium acetate (1.64g, 0.0204mol) was dissolved in 10ml of N, N-dimethylformamide and added to the intermediate, and the reaction was stirred at 50 ℃ for 8 hours, and 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 give a product M5. The yield was 79%, and the nuclear magnetization is shown in FIG. 5.

Example 6: raw materials

Preparation: the product M6 was prepared from the starting material by the method of example 2. Yield 83%, nuclear magnetization is shown in fig. 6.

Example 7: raw materials

Preparation: the product M7 was prepared from the starting material by the method of example 3. Yield 85% and nuclear magnetization as shown in figure 7.

Example 8: raw materials

Preparation: the product M8 was prepared from the starting material by the method of example 1. Yield 75%, nuclear magnetization is shown in figure 8.

Example 9: raw materials

Preparation: the product M9 was prepared from the starting material by the method of example 2. Yield 80% and nuclear magnetization are shown in figure 9.

Example 10: raw materials

Preparation: the product M10 was prepared from the starting material by the method of example 4. Yield 80% and nuclear magnetization are shown in figure 10.

Example 11: raw materials

Preparation: the product M11 was prepared from the starting material by the method of example 4. Yield 76% and nuclear magnetization are shown in FIG. 11.

Example 12: raw materials

Preparation: the product M12 was prepared from the starting material by the method of example 3. Yield 82%, nuclear magnetization is shown in fig. 12.

Example 13: raw materials

Preparation: the product M13 was prepared from the starting material by the method of example 1. Yield 80% and nuclear magnetization is shown in figure 13.

Example 14: raw materials

Preparation: the product M14 was prepared from the starting material by the method of example 2. Yield 86%, nuclear magnetization is shown in fig. 14.

Example 15

The unsaturated carbon chain type boron trifluoride organic salt electrolyte protected in the invention is mainly used for three aspects: application direction 1: the electrolyte is used as an additive in electrolytes (including liquid and solid), 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 battery are greatly improved. Application direction 2: the structure containing double bonds can also initiate polymerization into a single-ion conductor polymer electrolyte, and is applied to gel batteries and all-solid batteries. Application direction 3: the unsaturated carbon chain boron trifluoride organic salts of the present application may also be used as lithium/sodium salts in electrolytes, both in liquid and solid form. The performance of the present application is described below by way of tests.

Firstly, as an electrolyte additive

(1) Positive pole piece

Adding the active substance of the main material of the positive electrode, 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, and uniformly mixing and stirring to obtain positive electrode slurry with certain fluidity; and coating the anode slurry on an aluminum foil, drying and compacting 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), 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

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 an electrolyte

M1-M14, an organic solvent, a conventional lithium/sodium salt and a conventional additive are uniformly mixed to obtain a series of electrolytes E1-E14, wherein the used solvents are Ethyl Methyl Carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), Ethylene Carbonate (EC) and Propylene Carbonate (PC). Conventional additives are fluoroethylene carbonate (FEC), Vinylene Carbonate (VC), trimethyl phosphate (TMP), ethoxypentafluorocyclotriphosphazene (PFPN),Vinyl sulfate (DTD); conventional lithium salts are lithium bis (oxalato) borate (LiBOB), lithium difluoro (oxalato) borate (LiODFB), lithium bis (fluorosulfonyl) imide (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 E14 formulated with M1 to M14 as additives

Note: 1M means 1 mol/L.

Comparison sample: and replacing M1-M14 with blanks according to the proportion of E1-E14 (namely, not adding M1-M14), thus obtaining corresponding conventional electrolyte comparison samples L1-L14.

(4) Button cell assembly

Electrolyte series E1-E14 containing the structure of the embodiment as an additive and conventional electrolyte L1-L14 are assembled into the button cell in a comparison mode, and the button cell is specifically as follows: negative electrode shell, negative electrode pole piece, PE/Al₂O₃The button cell is assembled by a diaphragm, an electrolyte, a positive pole piece, a stainless steel sheet, a spring piece and a positive shell to carry out long circulation test 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 circular sheet with the diameter of 12mm, the negative pole piece is a circular sheet with the diameter of 14mm, the diaphragm is a circular sheet with the diameter of 16.2mm, and is a commercial Al circular sheet₂O₃a/PE porous separator.

The battery systems formulated with E1 to E14 were example battery 1 to example battery 14, respectively, and the battery systems formulated with L1 to L14 were comparative example battery 1 to comparative example battery 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 arrangement and test mode of example and comparative example cells

Table 4 comparison of test results of example cell and comparative example cell

From the test results of the battery in the embodiment and the battery in the comparative example, in the button cell, 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 lithium/sodium battery using the structure M1-M14 as the electrolyte additive are much better than those of the lithium/sodium battery without the electrolyte additive, and the performance of the lithium/sodium battery is superior to that of the conventional additive at present. In addition, the battery using the additive containing lithium borate salt shows synergistic effect in the presence of conventional additives, and the battery performance shows more excellent electrochemical performance.

II, as lithium salt in electrolyte

(1) Preparing an electrolyte

M1, M3, M6, M10 and M12, wherein an organic solvent, a conventional additive and a conventional lithium salt are uniformly mixed to obtain a series of electrolytes R1, R3, R6, R10 and R12, and a conventional lithium salt, an organic solvent and a conventional additive are uniformly mixed to obtain a series of conventional electrolytes Q1, Q3, Q6, Q10 and Q12, and the used solvent and the conventional additive comprise the solvent and the conventional additive described in the first embodiment. The specific components and ratios of the electrolyte are shown in table 5.

Table 5 electrolyte prepared from lithium salt

(2) Battery assembly

The obtained series of electrolytes R (shown in table 5) and the conventional 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 cycling manner of the cell were the same as those of the button cell shown in "one" of this example, i.e.,

cells

1, 3, 6, 10, and 12 and the corresponding comparative cells, 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 example and comparative button cell configurations and test protocols

Table 7 comparison of test results of examples and comparative examples cells shown in table 6

In summary, the boron-containing lithium salt provided by the invention is used as a lithium salt alone or forms a double salt with a conventional lithium salt in a non-aqueous solvent, lithium ions are easy to be solvated, and a high ionic conductivity is provided for a battery, and in a liquid lithium battery system in which LCO and NCM811 are used as a positive electrode and SiOC450 and Li are used as a negative electrode, the lithium salt shows very excellent electrochemical performance, and the first-effect and first-week discharge capacity and capacity retention rate are high, and the performance of the lithium salt is equivalent to or slightly superior to that of a battery corresponding to a conventional lithium salt.

Three, single ion conductor polymer electrolyte

(1) Preparation of electrolyte

Monomers (compounds in the examples of the present application), plasticizers, battery additives, lithium salts, and initiators were uniformly stirred to form a precursor solution, and precursors S1 to S4 and S6 to S14 were obtained, specifically in the formulation shown in table 8. The initiator used is Azobisisobutyronitrile (AIBN) or dibenzoyl peroxide (BPO).

TABLE 8 precursor solution composition

In the above table, LiNO₃Is lithium nitrate.

(2) Battery assembly

Electrolyte precursor solutions S1-S4 and S6-S14 obtained from the following table 8 are respectively assembled into soft package batteries, namely batteries (namely, embodiments) 1-4 and 6-14; 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 lithium secondary battery, wherein the battery assembly system is A2, and the diaphragm uses commercial PE/Al₂O₃A porous membrane.

(3) Battery testing

After the secondary batteries prepared in examples 1 to 4 and 6 to 14 were completely cured, the first-cycle discharge capacity, the first-cycle efficiency and the capacity retention rate after 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 0.2C/0.2C48 cycles (C represents the rate), and the test results are shown in table 9.

Table 9 test results of the batteries of the examples

As shown in table 9, it was found from the test data in the example batteries that the precursors S1 to S4 and S6 to S14, which are composed of the radically polymerizable monomers M1 to M4 and M6 to M14, were cured in situ to serve as polymer electrolytes, and in the solid lithium battery system in which NCM811 is the positive electrode and silicon oxycarbide (SiOC450) is the negative electrode, the electrochemical performance was very excellent, and the first-pass discharge capacity, and the capacity retention rate were high. In addition, the batteries prepared in examples 1-2, 6, 9-10, and 13 were not added with additional lithium salt, see table 8, but all of them were able to be normally cycled, see table 9, which shows that the boron trifluoride salt of the present application is in a salt structure, and in the absence of salt, a solid electrolyte with excellent performance can be obtained after polymerization of such monomers. Also, when additionally used in combination with a conventional lithium salt, the battery exhibits more excellent electrochemical properties due to an increased amount of dissociated ions.

In addition, the figure part picks some battery test effect graphs as additives, lithium salt and polymerized monomer for display. Fig. 15-18 are graphs comparing the effect of the battery 1/6/10/12 made as an electrolyte additive in example 1/6/10/12 with that of a corresponding comparative battery 1/6/10/12 without the example of the present invention. FIGS. 19-20 are graphs comparing the effect of the battery 3/12 made of the lithium salt electrolyte of example 3/12 with that of a comparative battery 3/12 without the inventive example. FIG. 21 is a graph showing the effect of a battery 2 as a polymer electrolyte after polymerization in example 2; FIG. 22 is a graph showing the effects of example 7 on a battery 7 formed as a polymer electrolyte after polymerization. The figures also show that the structure of the application has excellent effect. In addition, in the circulation diagram, there are small squares on the upper surface

The lines of (A) represent the cells of the examples, with small circles

The line representing the comparative example cell shows that the lines representing the example cells are substantially all above the line representing the comparative example cell, and the example cells are more effective.

In summary, the first cycle efficiency, discharge capacity, capacity retention rate, and other properties have a direct and significant impact on the overall performance of the battery, which directly determines whether the battery can be used. 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 test 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 in the application also show better effect when being used together. More surprisingly, the component can also initiate polymerization to form a single-ion conductor polymer electrolyte, and the single-ion conductor polymer electrolyte can be applied to gel batteries and all-solid batteries, and the structure of the application can simultaneously have double effects of being used as lithium/sodium salt and being used as a monomer, so that the battery can still normally circulate under the condition of not adding the lithium/sodium salt. In addition, the component can also be used as salt in electrolyte, the effect is very good, and tests show that the component is superior to the existing mature component. More importantly, the structure type of the application is greatly different from the conventional structure, a new direction and thought are provided for research and development in the field, a large space is brought for further research, and one structure in the application has multiple purposes and is extremely significant.

Example 16:

for further study and understanding of the structural properties in the present application, the applicant evaluated its effect on the long cycle performance of the cell at room temperature as an electrolyte additive, respectively with the following structure W. Structure M15 of the present application (shown below).

(1) Electrolyte preparation

TABLE 10W, M15 electrolytes S1 to S2 prepared as the electrolytes

Wherein S0 is a control group.

(2) Button cell assembly

The obtained electrolytes S0-S2 were assembled into button cells, and the sizes of the positive and negative electrodes, the separator, the assembly method, and the battery cycle were the same as those of the button cells shown in "I" of example 15, namely, batteries Y0-Y2, respectively. The specific configuration, cycling profile and voltage range of the cell are shown in table 11, and the test results are shown in table 12.

Watch 11 button cell assembling and testing mode

TABLE 12 test results for the cells

As can be seen from the test results of the batteries Y0-Y2, W, M15 as an electrolyte additive can improve the first effect, the 1-50-cycle discharge specific capacity and the capacity retention rate of the battery. However, M15 showed a more significant increase in the first-effect and first-cycle specific discharge capacity of the battery compared to W, probably because W contained only 1-OBF₃M, and contains 2-OBF₃M15 of M consumes less lithium ions extracted from the positive electrode in the process of forming a good passivation layer, so that the first effect, the first-cycle specific discharge capacity and the 50-cycle capacity retention rate of the battery are improved. And the boron trifluoride organic salt in the application can be used as an additive and a lithium salt/sodium salt, such as M15, when the boron trifluoride organic salt is in an electrolyte, and the boron trifluoride organic salt can act synergistically in the electrolyte, so that the effect is better than that of other components. The applicant is still in further research with a clearer and more clear mechanism. However, in any case, it is certain that the OBF₃Storage of MAnd the amount has a substantial effect on the cell performance.

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 14. In examples 6 to 14 and the preparation methods of the above-listed structures, all of which are methods in which a boron trifluoride organic salt is obtained by reacting a raw material, an M source and a boron trifluoride compound, i.e., in which-OH in the raw material is changed to-OBF₃M, 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.

In the present invention, it is also noted that (i) -OBF₃-BF of M₃It must be bonded to the oxygen atom O, which is in turn bonded by a single bond to the carbon atom C, so that O cannot be a ring-located oxygen. If O is bonded to N, S or other atoms, the structure is greatly different from the present application, and whether the structure can be applied to the electrolyte of the present application, what effect and application scene are not predictable, and therefore, the inventors of the present invention conducted separate studies on the structures and did not conduct much discussion here; ② the structure does not contain sulfydryl.

In the present application, both of the above cases need to be satisfied, and if not, the properties of the present application are greatly different from those of the present application, so that the application scene or effect after the change is not well predicted, and may be greatly changed, and if valuable, the present inventors will make a special study separately later.

It should be noted that, the applicant has made a very large number of tests on the series of structures, and after the first structural effect, the sum of the subsequent test exploration and data supplementation spans about two years, and sometimes, for better comparison with the existing system, there is the same structure and system, and more than one test is made, so that there may be a certain error in different tests.

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 unsaturated carbon chain electrolyte, characterized in that: the electrolyte comprises unsaturated carbon chain type boron trifluoride represented by the following general formula I:

in the above formula I, R or R₁Independently a first chain without or containing at least one atom; and R₁Is not absent at the same time;

R₂、R₃independently a second chain free or containing at least one atom;

m is a metal cation; and-OBF₃The atom to which M is attached is a carbon atom C;

the first chain and the second chain are both carbon chains;

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, the second chain and the chain substituent group at least contain one unsaturated bond, and the unsaturated bond comprises a carbon-carbon double bond or a carbon-carbon triple bond.

2. The electrolyte of claim 1, wherein: in the general formula I, R₂、R₃Independently a carbon chain of 0-5 atoms; r, R₁Independently a carbon chain of 1 to 25 atoms;

preferably, the main chain of the structure of the general formula I is a chain of 1 to 25 carbon atoms in length; r₂、R₃Independently a carbon chain of 0-3 atoms.

3. The electrolyte of claim 1, wherein: the chain substituent is selected from alkyl, alkenyl, alkynyl, alkenylalkynyl,

Or a salt substituent;

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; the first substituent is selected from H, halogen atom, carbonyl, ester group, aldehyde group, ether oxygen group, ether sulfur group, ═ O, ═ S, and,

Nitro, cyano, amino, amide, sulfonamide, sulfoalkane, hydrazino, diazo, alkyl, heteroalkyl, cyclic substituents, salt substituents, and any of these groups wherein hydrogen H is substituted with a halogen atom; the hydrocarbon group comprises alkyl, alkenyl, alkynyl and alkenylalkynyl, and the heterohydrocarbon group is a hydrocarbon group containing at least one heteroatom; the mixture isThe atoms are selected from halogen, S, N, O, P, Se, Ca, Al, B or Si;

wherein R is₅、R₆Independently is H, alkyl, alkenyl or alkynyl; r₂、R₃Independently is H, hydrocarbyl or heterohydrocarbyl; such salt substituents include, but are not limited to, sulfate, sulfonate, sulfonimide, carbonate, carboxylate, ether, ammonium, silicate, phosphate, hydrochloride, nitrate, azide.

4. The electrolyte of claim 3, wherein: for said formula I, it comprises:

(1)R₂and R₃All are absent, R and R₁Independently a first chain containing at least one C atom, noted

two-OBF₃M is linked to R and R, respectively₁On any one of the C atoms;

(2)R₁、R₂and R₃Both are absent, R is a first chain containing at least one C atom, two-OBF₃M is linked to the same C, denoted

The R, R₁、R₂Or R₃Can have the substituent attached thereto.

5. The electrolyte of claim 4, wherein: for the general formula I, the structure can be any one of the following structures:

wherein Q is₁、Q₂represents-OBF₃M; z in each structure₀～Z₁₈Are each independently selected from the group defined by the substituents of any one of claims 1 to 4.

6. The electrolyte of claim 5, wherein: in the general formula I, Z in each structure₀～Z₁₈Are each independently selected from a second substituent selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, ethenyl, propenyl, ethynyl, propynyl, ═ CH₂、＝CHCH₃、＝CHCH₂CH₃Or a cyclic substituent; the cyclic substituent comprises cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl or polycyclic; the cyclic substituent is optionally linked to a first substituent.

7. The electrolyte of claim 6, wherein:

the second substituent is selected from H, methyl, ethyl, propyl, isopropyl, butyl, ethenyl, ethynyl, ═ CH₂、＝CHCH₃Or a cyclic substituent; the cyclic substituent is selected from phenyl, pyridine, thiophene or

The first substituent is selected from H, alkyl, halogen atom, nitro, amino, aldehyde group, halogenated alkyl, sulfonyl or alkoxy;

and the second substituent Z attached to the terminal carbon atom is preferably H or methyl.

8. The electrolyte of claim 1, wherein: the general formula I is lithium salt, potassium salt, sodium salt, calcium salt or magnesium salt, preferably lithium salt, potassium salt or sodium salt.

9. A method for producing the electrolyte according to any one of claims 1 to 8, characterized in that: the method comprises the following steps: unsaturated carbon chain binary structure containing two-OH, boron trifluoride compound and M source react to obtain a product, namely, the product contains two-OBF₃M is an unsaturated carbon chain type boron trifluoride structure.

10. Use of the electrolyte of any one of claims 1 to 8 in a secondary battery, wherein: the application is as follows: the electrolyte can be used as a salt, as an additive, and as a polymeric monomer;

the use includes use in a liquid electrolyte, a solid electrolyte, an electrolyte composite membrane or a gel electrolyte, each independently comprising an electrolyte of the unsaturated carbon chain type according to any one of claims 1 to 8;

preferably, the application further comprises application as a battery or battery pack, the battery comprising the unsaturated carbon chain-based electrolyte of any one of claims 1 to 8, and a positive electrode, a negative electrode, a separator and a package can; the battery pack includes the battery.