CN114230592A

CN114230592A - Saturated carbon chain electrolyte and preparation and application thereof

Info

Publication number: CN114230592A
Application number: CN202010941839.0A
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 a saturated carbon chain electrolyte, and preparation and application thereof, wherein the electrolyte comprises a boron trifluoride salt represented by the following general formula I: wherein, R, R₁Independently a first chain free or containing at least one carbon atom; and R₁Is not absent at the same time; r₂Or R₃Independently a second chain free or containing at least one carbon atom; and-OBF₃The atom to which M is attached is a carbon atom C; m is a metal cation; the first chain and the second chain are both saturated carbon chains; h on any one C of the first and second chains may be independently substituted with a substituent. The boron organic compound can be used as electrolyte salt and additive, and has good effect.

Description

Saturated carbon chain electrolyte and preparation and application thereof

Technical Field

The invention relates to the technical field of batteries, in particular to a saturated 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. 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, BF-containing samples were also only investigated by very individual researchers₃Compounds of the group were studied sporadically and all contained 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, resistance is greatly increased, time cost and economic cost are extremely high, and results are not well predicted, so that the research team only always contains one-OBF₃M was studied. Even if the pair contains one-OBF₃M is studied, and the reference value is very small because of the few prior art, while the research on two groups is not carried outAny reference is made to the 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 study of the structure of M linked to a saturated chain, i.e. two-OBF₃M is linked to a saturated carbon chain. This is because the chemical properties such as electrical property and the like of the two OBFs are relatively special and self-integrated, and the two OBFs with strong polarity₃M, when attached to a saturated carbon chain, also affects the chemical and physical properties of the entire chain, where it is substantially different from rings and other types of chain structures, etc., and thus the relationship or predictability between each other is uncertain. Thus, the linkage of-OBF to the saturated 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. Therefore, the present application identifies the subject as having two-O-BF groups linked in a saturated chain₃M, thereby more specifically determining-O-BF₃M is linked to the saturated chain.

Disclosure of Invention

The invention provides a saturated 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 is to provide a saturated carbon chain type electrolyte including a saturated carbon chain type boron trifluoride salt represented by the following general formula I:

in the above formula I, R, R₁Independently is none or containsA first chain having at least one carbon atom; and R₁Is not absent at the same time; r₂Or R₃Independently a second chain free or containing at least one carbon atom; and-OBF₃The atom to which M is attached is a carbon atom C; m is a metal cation; the first chain and the second chain are both saturated carbon chains; h on any one C of the first and second chains may be independently substituted with a substituent.

Preferably, in formula I, R or R₁Independently a saturated carbon chain of 1 to 30 atoms; r₂、R₃Independently a saturated carbon chain of 0-5 atoms.

Preferably, the substituent includes H, saturated alkyl or cyclic substituent. Further preferably, the cyclic substituent includes 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 having two or more ring structures at the same time; the cyclic substituent can optionally be linked to a first substituent.

Preferably, the main chain in the general structural formula I is a chain with the length of 1-20 carbon atoms; the second chain is a saturated carbon chain of 0-3 atoms.

Preferably, in formula I, comprising: (1) r₂And R₃All are absent, R and R₁Independently a first chain containing at least one carbon 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 carbon atom, two-OBF₃M is linked to the same C, denoted

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

The R, R₁、R₂Or R₃Can be attached to the substituent.

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

wherein Q is₁、Q₂represents-OBF₃M; z in each structure₀～Z₂₄Are each independently a substituent as described in any preceding paragraph, preferably said substituent is selected from the group consisting of H, C₁-C₆Alkyl or said cyclic substituent.

Preferably, the substituents are selected from H, methyl, ethyl, propyl, isopropyl, butyl, isobutyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and polycyclic, any of these cyclic substituents H being independently substituted by the first substituent; preferably, the first substituent is selected from H, methyl, ethyl, halogen, nitro, cyano, aldehyde, ester, amino, alkoxy, alkylthio, ═ O, ═ S, ═ CH₂. And a substituent Z attached to the last carbon atom (refer to Z as described above)₀～Z₂₄) Preferably H or methyl.

Preferably, the cyclic substituent is selected from the group consisting of cyclopropane, cyclopropene, ethylene oxide, aziridine, cyclobutane, cyclobutenyl, cyclobutylheteroalkenyl, cyclohexane, dithiane, 1, 2-dithiane, benzene ring, benzenesulfonyl, pyridine ring, cyclopentyl, cyclopentene, furan, pyrrole, thiophene and thiophene

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: a saturated carbon chain binary structure containing two-OH groups, a boron trifluoride compound and an M source (such as an M salt, an M base or other substances capable of providing a metal M to the general formula I of the application) to obtain a product, namely, the product contains two-OBF₃A saturated carbon chain type boron trifluoride structure of M.

The present invention also provides a use of the saturated carbon chain electrolyte according to any one of the above paragraphs in a secondary battery, the use comprising: the electrolyte can be used both as a salt and as an additive.

The invention also provides an additive applied to a lithium/sodium battery, which comprises saturated carbon chain type boron trifluoride salt described in any one of the above general formulas.

The invention also provides a lithium/sodium salt applied to a lithium/sodium battery, wherein the lithium/sodium salt comprises a saturated carbon chain type boron trifluoride salt described in any one of the above general formulas.

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 an electrolyte of the saturated carbon chain type as described in any one of the preceding 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 saturated 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 provides a saturated carbon chain electrolyte, and a preparation method and an application thereof, and the saturated carbon chain electrolyte mainly has the following beneficial effects:

the electrolyte in the present application creatively combines two-OBF₃M complexIn one compound, and 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 compounded 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. In addition, the structure of the present application can act synergistically as an additive and a salt in an electrolyte to provide excellent effects over conventional additives or lithium/sodium salts, e.g., as a lithium salt, which not only provides good ion transport, but also forms a stable passivation layer on the electrode surface to prevent PEO or other groups during battery cyclingThe fractions are further decomposed, and thus the battery exhibits more excellent long-cycle stability.

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 12 are nuclear magnetic hydrogen spectra of products shown in examples 1 to 12 of the present invention, respectively;

FIGS. 13-16 are graphs illustrating the cycling effect of the electrolyte additive of the present application;

FIGS. 17 to 18 are graphs showing the effect of the cycling of lithium salts as electrolytes in the present application;

FIG. 19 is a graph illustrating the cycling effect of lithium salts as solid electrolytes in accordance with the present application;

fig. 20 is an infrared view of structure M14 of the present application.

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.

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

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

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

And the like.

The invention provides a binary organic boron trifluoride salt which can be used as an electrolyte additive and an electrolyte lithium/sodium salt 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: raw materials, 3-ethyl-2, 4-pentanediol (1.32g, 0.01mol), 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 M1. The yield was 77%, and the nuclear magnetization is shown in FIG. 1.

Example 2: raw materials

The preparation method comprises the following steps: a metallic lithium plate (0.7g, 0.1mol) was slowly added to the starting material 1, 13-tridecanediol (2.16g, 0.05mol) under an argon atmosphere, reacted at room temperature for 1 hour, and then heated 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 at 50 ℃ for reaction for 6 hours, drying the obtained mixed solution under reduced pressure at 50 ℃ 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 85%, and the nuclear magnetization is shown in FIG. 2.

Example 3: raw materials

The preparation method comprises the following steps: 1, 6-hexanediol (1.19g, 0.01mol) and boron trifluoride diethyl etherate (2.98g, 0.021mol) as raw materials were mixed uniformly in 15ml of ethylene glycol dimethyl ether in an argon atmosphere, and reacted at room temperature for 12 hours. The obtained mixed solution is decompressed and dried at 30 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. 14ml of butyllithium in hexane (c: 1.6mol/L) was added to the intermediate, the reaction was stirred at room temperature for 10 hours, the resulting mixture was dried under reduced pressure at 40 ℃ under a vacuum degree of about-0.1 MPa, and the resulting crude product was washed with cyclohexane 3 times, filtered and dried to obtain M3. The yield was 86%, and the nuclear magnetization is shown in FIG. 3.

Example 4: raw materials

The preparation method comprises the following steps: the starting materials 3- (tert-butyl) pentane-2, 4-diol (1.6g, 0.01mol) and lithium methoxide (0.76g, 0.02mol) were mixed with 20ml of methanol under a nitrogen atmosphere, and reacted at room temperature for 12 hours. The obtained mixed solution is decompressed and dried at 30 ℃ and the vacuum degree of about-0.1 MPa to remove the solvent, and an intermediate is obtained. Boron trifluoride tetrahydrofuran complex (3.07g, 0.022mol) is added into the intermediate, stirred and reacted for 14 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 78%, nuclear magnetization is shown in figure 4.

Example 5: raw materials

The preparation method comprises the following steps: raw materials, 2, 4-dimethyl-2, 4-pentanediol (1.32g, 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 30 ℃ for 12 hours, and the resulting mixed solution was dried under reduced pressure at 35 ℃ and a vacuum degree of about-0.1 MPa to remove the solvent, thereby obtaining an intermediate. Lithium acetate (1.35g, 0.0204mol) is dissolved in 10ml DMF 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 M5 is obtained after filtration and drying. The yield was 78%, and the nuclear magnetization is shown in FIG. 5.

Example 6: raw materials

The preparation method comprises the following steps: raw materials, 2, 5-dimethyl-2, 5-hexanediol (1.46, 0.01mol) and sodium hydroxide (0.80g, 0.02mol), were mixed uniformly with 10ml of a methanol solution under a nitrogen atmosphere, and reacted at 15 ℃ 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. Adding boron trifluoride diethyl etherate (2.98g, 0.021mol) into the intermediate, adding 10ml of ethylene glycol dimethyl ether solvent, stirring at room temperature for 24 hours, drying the obtained mixed solution under reduced pressure at the temperature of 20 ℃ and the vacuum degree of about-0.1 MPa, washing the obtained solid with dichloromethane three times, filtering and drying to obtain a product M6. The yield was 72%, and the 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 4. 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 80% and nuclear magnetization are shown in figure 8.

Example 9: raw materials

Preparation: the product M9 was prepared from the starting material by the method of example 5. 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 1. Yield 86%, nuclear magnetization is shown in fig. 10.

Example 11: raw materials

Preparation: the product M11 was prepared from the starting material by the method of example 4. Yield 80% and nuclear magnetization are shown in figure 11.

Example 12: raw materials

Preparation: the product M12 was prepared from the starting material by the method of example 1. Yield 79% and nuclear magnetization are shown in fig. 12.

Example 13

The saturated carbon chain boron trifluoride organic salt electrolyte (including liquid and solid) protected by the invention is mainly used as an additive, mainly plays a role in generating a passivation layer, and carries ions capable of being dissociated, 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. Moreover, the saturated carbon chain boron trifluoride organic salts can also be used as lithium salts in electrolytes (including liquid and solid). 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 Super P are selected as 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 Super P 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-M12, an organic solvent, a conventional lithium/sodium salt and a conventional additive are uniformly mixed to obtain a series of electrolytes E1-E12, 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 E12 formulated with M1 to M12 as additives

Note: 1M means 1 mol/L.

Comparison sample: and replacing M1-M12 with blanks according to the proportion of E1-E12 (namely, not adding M1-M12), thus obtaining corresponding conventional electrolyte comparison samples L1-L12.

(4) Button cell assembly

Electrolyte series E1-E12 containing the structure of the embodiment as an additive and conventional electrolyte L1-L12 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 the diaphragm, the electrolyte, the positive pole piece, the stainless steel sheet, the spring piece and the positive shell, and long cycle test is carried out at room temperature, wherein the cycle mode is 0.1C/0.1C 1 cycle0.2C/0.2C 5 week and 1C/1C 44 week (C represents multiplying power), the positive pole piece is a round piece with the diameter of 12mm, the negative pole piece is a round piece with the diameter of 14mm, the diaphragm is a round piece with the diameter of 16.2mm, and the diaphragm is commercial Al₂O₃a/PE porous separator.

The battery systems prepared from E1-E12 are batteries 1-12, respectively, and the battery systems prepared from L1-L12 are comparative batteries 1-12, respectively. The specific configuration and voltage range of the cell are shown in table 3. The results of the specific discharge capacity at the first cycle, the first cycle efficiency, and the capacity retention rate at 50 cycles of the batteries 1 to 12 and the comparative batteries 1 to 12 at room temperature are shown in table 4.

TABLE 3 arrangement and test mode for the batteries 1-12 of the examples and comparative batteries 1-12

TABLE 4 comparison of test results for batteries 1-12 of examples and comparative batteries 1-12

Example and comparative batteries	First week discharge specific volume (mAh/g)	First week efficiency (%)	Capacity retention (%) at 50 weeks of circulation
				Battery
1	161.7	77.8	83.4
				Comparative battery 1	132.1	67.6	73.5
Battery 2	160.5	78.2	82.9
				Comparative battery 2	131.9	68.3	73.8
Battery 3	166.2	82.1	87.7
				Comparative battery 3	158.9	80.2	82.3
Battery 4	160.7	79.3	83.8
				Comparative battery 4	131.6	68.0	73.6
Battery 5	174.1	80.9	90.5
				Comparative battery 5	160.4	79.5	87.3
Battery 6	110.6	80.5	90.3
				Comparative battery 6	95.2	70.6	87.2
Battery 7	173.9	80.7	90.2
				Comparative battery 7	162.7	79.4	87.9
Battery 8	172.5	80.8	90.6
				Comparative battery 8	142.2	75.3	83.0
Battery 9	202.3	91.9	89.9
				Comparative battery 9	195.1	90.2	86.3
Battery 10	200.7	91.4	87.4
				Comparative battery 10	191.5	83.7	80.5
Battery 11	170.2	83.2	88.9
				Comparative battery 11	159.3	79.7	85.6
Battery 12	142.7	87.6	88.7
				Comparative battery 12	128.3	80.4	75.8

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-M12 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 batteries using the additives containing lithium borate salts exhibit more excellent electrochemical performance in the presence of conventional additives.

II, as lithium salt in electrolyte

(1) Preparing an electrolyte

M1, M2, M5, M10, M11 and M12, an organic solvent, a conventional additive and a conventional lithium salt are uniformly mixed to obtain a series of electrolytes R1, R2, R5, R10, R11 and R12, the conventional lithium salt, the organic solvent and the conventional additive are uniformly mixed to obtain a series of conventional electrolytes Q1, Q2, Q5, Q10, Q11 and Q12, and the used solvent and the conventional additive comprise the solvent and the conventional additive described in the 'one' of the 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

1,2, 5, 10, 11, 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 configuration and test mode for example and comparative batteries

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

In summary, the boron-containing organic 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 easily 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-cycle discharge capacity and the capacity retention rate are high, and the performance of the lithium salt is equivalent to or superior to that of a battery corresponding to a conventional lithium salt.

Thirdly, as lithium salt in solid electrolyte

(1) Preparation of Polymer electrolyte Membrane

M5, M8, M9, M12, polymer, inorganic filler and solvent are mixed uniformly to obtain series of polymer electrolyte slurry, the slurry is coated on a glass plate in a scraping way, after drying and removing the solvent, polymer electrolyte membranes G5, G8, G9 and G12 and polymer comparative electrolytes G '1-G' 2 are obtained, and specific components, proportions and the like are shown in Table 8. The polymer was polyethylene oxide (PEO).

TABLE 8 concrete composition and compounding ratio of polymer electrolyte

Polymer electrolyte membrane	Polymer and method of making same	Lithium/sodium salt	Inorganic filler	The former mass ratio	Solvent(s)
						G5	PEO100 ten thousand	M5	200nmLLZO	4.2：1：0.8	DMF
G8	PEO100 ten thousand	M8	/	4.2：1	DMF
						G9	PEO100 ten thousand	M9	200nmLLZO	4.2：1：0.8	DMF
G12	PEO100 ten thousand	M12	/	4.2：1	DMF
						G’1	PEO100 ten thousand	LiTFSI	200nmLLZO	4.2：1：0.8	DMF
G’2	PEO100 ten thousand	LiTFSI	/	4.2：1	DMF

(2) Preparation of positive pole piece

In an environment with the water content lower than 100ppm, adding the active substance of the positive electrode main material, the polymer and the lithium salt, the electronic conductive additive and the binder into NMP according to the mass ratio of 80:10:5:5, mixing and stirring uniformly, coating the positive electrode slurry on aluminum foil, and drying to obtain the all-solid-state positive electrode piece. Lithium cobaltate (LiCoO) is selected as the active material₂LCO for short), nickel cobalt lithium manganate (NCM811 for selection), Super P for electronic conductive additive, polyvinylidene fluoride (PVDF) for binder

(3) Battery assembly and testing

The polymer electrolyte membrane and the positive and negative pole pieces are assembled into the all-solid button cell, which comprises the following specific steps: and assembling the negative electrode shell, the Li sheet, the polymer electrolyte membrane, the positive electrode sheet, the stainless steel sheet, the spring sheet and the positive electrode shell into a button cell to obtain the lithium secondary cell, and carrying out 50 ℃ long cycle test on the cell in a cycle mode of 0.1C/0.1C 2 cycle and 0.5/0.5C 48 cycle. The positive electrode plate is a circular plate with the diameter of 12mm, the Li plate is a circular plate with the diameter of 14mm, the polymer electrolyte membrane is a circular plate with the diameter of 16.2mm, the specific assembly system and the test method of the battery are shown in Table 9, and the test results are shown in Table 10.

TABLE 9 arrangement and test mode for cells and comparative cells

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

From the data in tables 9 and 10, it can be seen that the batteries prepared from M5, M8, M9 and M12 have excellent long-cycle stability and superior cycle performance to that of the battery corresponding to LiTFSI. This is because PEO has an electrochemical window of 3.9V, which is easily decomposed by the anode catalysis at 4.2V; furthermore, LiTFSI corrodes the current collector severely, thus showing poor cycling performance for the comparative battery. The lithium salt synthesized by the method has good ion transmission performance and good film-forming property, and a compact passivation layer is formed in the charging and discharging processes of the battery to prevent further decomposition of PEO, so that the long-circulating performance is good.

In addition, taking a lithium battery as an example, fig. 13-16 show a battery 2/5/10/12 made of the electrolyte additive of example 2/5/10/12 and a corresponding pair not containing the electrolyte additive of the inventionComparative graph of the effect of battery 2/5/10/12. FIGS. 17-18 are graphs comparing the effect of a battery 2/11 made of the lithium salt electrolyte of example 2/11 with a comparative battery 2/11 without the inventive example. Fig. 19 is a graph comparing the effects of the battery 12 of example 12 as a solid electrolyte lithium salt and the comparative battery 2 with LiTFSI as a lithium salt. 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 lines representing the cells of the comparative examples represent the cells of the comparative examples, and it can be seen that the lines representing the cells of the examples are all above the lines representing the cells of the comparative examples, and the cells of the examples have better effects.

The first cycle efficiency, specific discharge capacity, capacity retention rate and other properties have direct and significant influence on the overall performance of the battery, and directly determine whether the battery can be applied or not. Therefore, it is the goal or direction of many researchers in this field to improve these properties, but in this field, the improvement of these properties is very difficult, and generally about 3-5% improvement is a great progress. In the early 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 be used as salt in electrolyte, and the effect is very good, and tests show that the component is superior to the existing mature component. In addition, the battery can be applied to a solid-state battery, and the battery has an excellent effect and a good application prospect. More importantly, the structure type of the application is greatly different from the conventional structure, a new direction and thought are provided for the research and development in the field, a large space is brought for further research, and one structure in the application has multiple purposes and great significance.

Example 14:

for further study and understanding of the structural properties in the present application, the applicant evaluated the effect of the above-mentioned 3 structures as electrolyte additives on the long-cycle performance of the battery at room temperature. Structure selection M13 (shown below) for the present application, the following 3 comparative example structures are structure W1, structure W2 and W3, respectively.

(1) Electrolyte preparation

Tables 11W 1 to W3 and M13 electrolytes S1 to S4 each prepared as an electrolyte

Wherein S0 is a control group.

(2) Button cell assembly

The obtained electrolytes S0-S4 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 13, namely, batteries Y0-Y4, respectively. The specific configuration, cycling profile and voltage range of the cell are shown in table 12 and the test results are shown in table 13.

TABLE 12 cell Assembly and test mode

TABLE 13 test results for batteries

From the test results of the comparative examples Y0-Y4, it can be seen that the first efficiency, the 1-50-cycle discharge specific capacity and the capacity retention rate of the battery can be improved by using the W1-W3 and the M2 as electrolyte additives.However, compared with W1-W3, M13 has more obvious improvement on the first cycle discharge specific capacity of the battery, probably because of containing two-OBF₃M13 of M contains a lithium source, and lithium ions extracted from the positive electrode are less consumed in the process of forming a good passivation layer, so that the first effect, the first-cycle discharge specific capacity and the 50-cycle capacity retention rate of the battery are improved. And W1 contains 1-OBF₃the-OLi action in M, W2 is stronger, Li⁺The passivation layer is not easy to dissociate, so that the formed passivation layer mainly consumes a lithium source in the positive electrode, and the W2 does not contain the lithium source, so that the first-effect capacity, the first-cycle discharge specific capacity and the 50-cycle capacity retention rate are relatively low. I.e., the organic boron trifluoride salt in this application, acts as both an additive and a lithium/sodium salt in the electrolyte, such as M13, which itself acts synergistically in the electrolyte and is therefore more effective than the 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 OBF₃The presence and amount of M has a substantial effect on battery 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 all excellent, and other structures similar to these structures also have similar effects, and for reasons of space, the effects of the structures protected by the present invention will be described only by examples 1 to 12. In addition, the structure

The effects are better. And the preparation methods of examples 7-12 and the structures listed above all reacted the starting material, the M source, and the boron trifluoride compound to obtain the product trifluorideBoron organic salts, i.e. conversion of-OH in the raw material to-OBF₃M, M may be Li⁺、Na⁺Etc., and the other structures are unchanged, see examples 1-6. The structures not shown in the examples were prepared in the same manner.

The applicant has made many structures of the series, in addition to nuclear magnetism, infrared, etc., as shown in fig. 20

The infrared of M14, others are not collated because of space.

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. ③ the saturated carbon chain boron trifluoride salt electrolyte in the present application is preferably an organic substance in a non-polymerized state, and the polymerized state has unique characteristics and characteristics, so that the applicant may study the polymerized state specifically in the non-polymerized state later.

In the present application, the above three cases are all required to be satisfied, and if not, the properties of the present application are greatly different, so that the application scene or effect after change is not well predicted, and may be greatly changed, and if valuable, the present inventors will perform special research 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. A saturated carbon chain electrolyte, characterized in that: the electrolyte comprises saturated carbon chain type boron trifluoride represented by the following general formula I:

in the above formula I, R, R₁Independently a first chain free or containing at least one carbon atom; and R₁Is not absent at the same time;

R₂or R₃Independently a second chain free or containing at least one carbon atom;

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

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

h on any one C of the first and second chains may be independently substituted with a substituent.

2. The electrolyte of claim 1, wherein: in the general formula I, the compound has the following structure,

r or R₁Independently a saturated carbon chain of 1 to 30 atoms; r₂、R₃Independently a saturated carbon chain of 0-5 atoms;

3. The electrolyte of claim 2, wherein: the substituent comprises H, saturated alkyl or cyclic substituent;

preferably, the cyclic substituent includes 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 having two or more ring structures at the same time;

the cyclic substituent can optionally be linked to a first substituent, preferably the first substituent is of the same kind as the substituent.

4. The electrolyte of claim 3, wherein: in the general formula I, the formula comprises:

(1)R₂and R₃All are absent, R and R₁Independently a first chain containing at least one carbon 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 carbon atom, two-OBF₃M is linked to the same C, denoted

The R, R₁、R₂Or R₃Can be attached to the substituent.

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～Z₂₄Are each independently a substituent according to any one of claims 1 to 3, preferably selected from H, C₁-C₆Alkyl or said cyclic substituent.

6. The electrolyte of claim 5, wherein: said substituents being selected from the group consisting of H, methyl, ethyl, propyl, isopropyl, butyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and polycyclic, any H of these cyclic substituents being independently substitutable by said first substituent; preferably, the first substituent is selected from H, methyl, ethyl, halogen, nitro, cyano, aldehyde, ester, amino, alkoxy, alkylthio, ═ O, ═ S, ═ CH₂。

7. The saturated carbon chain-based electrolyte according to claim 6, characterized in that: the substituent Z attached to the terminal carbon atom is H or methyl;

the cyclic substituent is selected from the group consisting of cyclopropane, cyclopropene, ethylene oxide, aziridine, cyclobutane, cyclobutenyl, cyclohexane, dithiane, 1, 2-dithiane, benzene ring, benzenesulfonyl, pyridine ring, cyclopentyl, cyclopentene, furan, pyrrole, thiophene and thiophene

8. The saturated carbon chain-based electrolyte according to claim 1, characterized in that: 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: a saturated carbon chain binary structure containing two-OH, boron trifluoride compounds and an M source react to obtain a product, namely, the product contains two-OBF₃A saturated carbon chain type boron trifluoride structure of M.

10. Use of the saturated carbon chain-based electrolyte according to any one of claims 1 to 8 in a secondary battery, characterized in that: the application is as follows: the electrolyte can be used both as a salt and as an additive;

preferably, the application comprises application in a liquid electrolyte, a solid electrolyte, an electrolyte composite membrane or a gel electrolyte, each independently comprising an electrolyte of the saturated 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 saturated 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.