CN116621743A - Cyano-containing lithium salt, preparation method thereof, lithium battery electrolyte and lithium battery - Google Patents

Cyano-containing lithium salt, preparation method thereof, lithium battery electrolyte and lithium battery Download PDF

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CN116621743A
CN116621743A CN202310448698.2A CN202310448698A CN116621743A CN 116621743 A CN116621743 A CN 116621743A CN 202310448698 A CN202310448698 A CN 202310448698A CN 116621743 A CN116621743 A CN 116621743A
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lithium
carbonate
electrolyte
cyano
salt
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刘凯
曹清彬
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Tsinghua University
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Tsinghua University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0568—Liquid materials characterised by the solutes
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
    • C07C303/36—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of amides of sulfonic acids
    • C07C303/38—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of amides of sulfonic acids by reaction of ammonia or amines with sulfonic acids, or with esters, anhydrides, or halides thereof
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C303/00—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides
    • C07C303/36—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of amides of sulfonic acids
    • C07C303/40—Preparation of esters or amides of sulfuric acids; Preparation of sulfonic acids or of their esters, halides, anhydrides or amides of amides of sulfonic acids by reactions not involving the formation of sulfonamide groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C311/00—Amides of sulfonic acids, i.e. compounds having singly-bound oxygen atoms of sulfo groups replaced by nitrogen atoms, not being part of nitro or nitroso groups
    • C07C311/01—Sulfonamides having sulfur atoms of sulfonamide groups bound to acyclic carbon atoms
    • C07C311/02—Sulfonamides having sulfur atoms of sulfonamide groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton
    • C07C311/09—Sulfonamides having sulfur atoms of sulfonamide groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton the carbon skeleton being further substituted by at least two halogen atoms
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C311/00—Amides of sulfonic acids, i.e. compounds having singly-bound oxygen atoms of sulfo groups replaced by nitrogen atoms, not being part of nitro or nitroso groups
    • C07C311/22—Sulfonamides, the carbon skeleton of the acid part being further substituted by singly-bound oxygen atoms
    • C07C311/23—Sulfonamides, the carbon skeleton of the acid part being further substituted by singly-bound oxygen atoms having the sulfur atoms of the sulfonamide groups bound to acyclic carbon atoms
    • C07C311/24—Sulfonamides, the carbon skeleton of the acid part being further substituted by singly-bound oxygen atoms having the sulfur atoms of the sulfonamide groups bound to acyclic carbon atoms of an acyclic saturated carbon skeleton
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
    • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
    • H01M10/0566—Liquid materials
    • H01M10/0567—Liquid materials characterised by the additives
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a cyano-containing lithium salt, a preparation method thereof, lithium battery electrolyte and a lithium battery. According to the invention, nitrogen atoms with coordination ability in the cyano groups are coordinated with transition metals in the positive electrode material in the static and charging processes of the lithium battery, so that the positive electrode material is stabilized, dissolution of the transition metals and side reactions catalyzed by active sites of the transition metals are inhibited, and CEI film formation is indirectly optimized, so that a positive electrode interface is effectively passivated, the high-voltage resistance, the cycle stability and the rate capability of the battery are improved, and the equipment market with higher requirements on quick charge and long cycle life of the lithium battery can be further widened.

Description

Cyano-containing lithium salt, preparation method thereof, lithium battery electrolyte and lithium battery
Technical Field
The invention relates to the technical field of lithium ion batteries, in particular to cyano-containing lithium salt, a preparation method thereof, lithium battery electrolyte and a lithium battery.
Background
With the increasing demand for electronic devices and electric vehicles, lithium batteries are becoming an increasingly important energy storage device. The lithium battery is an efficient, lightweight, environment-friendly and rechargeable battery, and can be widely applied to the fields of electronic equipment, electric automobiles, energy storage systems, solar panels and the like.
With the gradual wide application range of lithium batteries, research and development of lithium batteries become a popular field, and the required energy density of the batteries is required to be higher and higher, and the effective working temperature range is also wider and wider, in particular, the charging speed and the service life are also longer and wider. However, conventional carbonate electrolytes always suffer from charge rate and cycle life problems due to high viscosity and low electrical conductivity. And these problems occur mainly because, when the charging speed is too fast, the moving speed of lithium ions cannot keep up with the change in current, resulting in a decrease in charging efficiency and possibly damaging the structure and performance of the battery. The change of the structure of the anode material inside the battery tends to further lead to the reduction of the charge and discharge capacity, the rapid decay of the capacity, the poor rate capability and the serious reduction of the cycle life of the battery.
The electrolyte research reported in the prior art mostly helps to improve the low-temperature performance by optimizing electrolyte lithium salt or solvent and adding functional additives, and the method is simple and has remarkable effect. CN113991181a discloses a method for mixing and collocating ethylene carbonate-based solvent and propylene carbonate-based solvent, optimizing the composition of electrolyte solvent, increasing the solvation action of lithium ions, and solving the problem of high-rate charge and discharge of the battery by using additives to greatly reduce the impedance of the solid electrolyte interface formed on the surface of the electrode material by the electrolyte. However, the use of graphite cathodes still has the problems of low energy density and cycle life. CN114122542a utilizes a new charge-discharge technology to promote the circulation of the cylindrical lithium iron phosphate material battery, and at the same time, the actual charge time of the battery can be properly shortened, but the technical scheme does not fundamentally solve the problems of cycle life and high-rate charge-discharge, so that the practical expansion is not realized.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention provides cyano-containing lithium salt, a preparation method thereof, lithium battery electrolyte and a lithium battery, which realize excellent quick charge and long cycle life of the battery and have higher practical application value.
In a first aspect, the present invention provides a cyano-containing lithium salt having the structure of formula I:
wherein Z is 1 、Z 2 Identical or different, each independently selected from single bond, - (CH) 2 ) x -、-(CH 2 CH 2 O) x -、-(CXH) x -、-(CX 2 ) x -、-(BH) x -、-(SiH 2 ) x One or more of-, sulfinyl, sulfonyl; x and y are integers from 0 to 10, and X=F, cl, br or I;
r is selected from one of fluorine atom, chlorine atom, bromine atom, iodine atom, C1-C10 haloalkyl, C1-C10 alkoxy, C2-C10 alkenyloxy, C2-C10 alkynyloxy, cyano, phenyl, fluorophenyl, trimethylsilyl, trifluoromethyl silyl, cyclotriphosphazene, fluorocyclotriphosphazene, isocyanate, lithium and C1-C10 alkyl.
In some embodiments of the invention, the cyano-containing lithium salt structure comprises a strong electron withdrawing capability-SO 2 CF 2 -S (=o) or a stronger ligand ability 2 -(CH 2 CH 2 O) 3 -CH 3 and-CN groups having complexing ability.
In a preferred embodiment of the invention, Z 1 Is a single bond or-CH 2 -，-Z 2 -R is-S (=o) 2 CF 3 or-S (=o) 2 -(CH 2 CH 2 O) 3 -CH 3 。
In a second aspect, the present invention also provides a method for preparing the above cyano-containing lithium salt.
The preparation method provided by the invention comprises the following steps:
R-Z 2 -Cl and H 2 N-Z 1 CN reacts in the presence of potassium carbonate to obtain potassium salt intermediate product, and thenAnd dissolving the potassium salt intermediate product in acetonitrile, and adding lithium tetrafluoroborate for substitution reaction to obtain a target product.
In a preferred embodiment of the invention, Z 1 Is a single bond, -Z 2 -R is-S (=o) 2 CF 3 。
The preparation method comprises the following steps: in the first step, triflyl chloride is dissolved in acetonitrile/tetrahydrofuran-water, and after the sample is completely dissolved, potassium carbonate is added, and then the mixture is stirred at room temperature. And (3) dissolving the nitrile amine in acetonitrile/tetrahydrofuran, slowly dripping the mixture into the solution after homogeneous phase is formed, reacting at the temperature of 10-25 ℃ for 12-24 hours, filtering the obtained mixture after the reaction, and performing rotary evaporation on the obtained filtrate to obtain a potassium salt intermediate product. And secondly, dissolving the intermediate product in acetonitrile, adding lithium tetrafluoroborate for displacement reaction to obtain a target product, wherein the reaction temperature is 10-25 ℃ and the reaction time is 3-8 h.
In another preferred embodiment of the invention, Z 1 is-CH 2 -，-Z 2 -R is-S (=o) 2 CF 3 。
The preparation method comprises the following steps: in the first step, triflyl chloride is dissolved in acetonitrile/tetrahydrofuran-water, and after the sample is completely dissolved, potassium carbonate is added, and then the mixture is stirred at room temperature. Aminoacetonitrile is dissolved in acetonitrile/tetrahydrofuran, after homogeneous phase is formed, the aminoacetonitrile is slowly dripped into the solution, the reaction temperature is 10-25 ℃, the reaction time is 12-24 hours, the obtained mixture is filtered after the reaction, and the obtained filtrate is distilled to obtain a potassium salt intermediate product. And secondly, dissolving the intermediate product in acetonitrile, adding lithium tetrafluoroborate for displacement reaction to obtain a target product, wherein the reaction temperature is 10-25 ℃ and the reaction time is 3-8 h.
In a further preferred embodiment of the invention Z 1 Is a single bond, -Z 2 -R is-S (=o) 2 -(CH 2 CH 2 O) 3 -CH 3 。
The preparation method comprises the following steps: in the first step, sulfonyl chloride structural reagent is dissolved in acetonitrile/tetrahydrofuran-water, and potassium carbonate is added after the sample is completely dissolved, and then the mixture is stirred at room temperature. And (3) dissolving nitrile ammonia in acetonitrile/tetrahydrofuran, slowly dripping the solution into the solution after homogeneous phase is formed, reacting at the temperature of 10-25 ℃ for 12-24 hours, filtering the obtained mixture after the reaction, and performing rotary evaporation on the obtained filtrate to obtain a potassium salt intermediate product. And secondly, dissolving the intermediate product in acetonitrile, adding lithium tetrafluoroborate for displacement reaction to obtain a target product, wherein the reaction temperature is 10-25 ℃ and the reaction time is 3-24 hours.
In a third aspect, the present invention provides a lithium battery electrolyte comprising the above cyano-containing lithium salt as a lithium salt electrolyte and/or additive.
The cyano-containing lithium salt is applied to a lithium battery, and can be used as a lithium salt electrolyte of a lithium battery electrolyte, or as an additive of the lithium battery electrolyte, or as both the lithium salt electrolyte and the additive of the lithium battery electrolyte.
In some embodiments of the invention, the cyano-containing lithium salt is used only as an additive in an amount of less than 20% by mass of the lithium battery electrolyte.
In some embodiments of the invention, the lithium battery electrolyte further comprises a lithium salt electrolyte, an organic solvent, and optionally a second additive. In essence, the cyano-containing lithium salt is used as an additive, without excluding that other components which may be used as additives are also included in the electrolyte.
Wherein the lithium salt electrolyte is one or more of lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluorooxalato borate, lithium tetrafluoroborate and lithium bis (oxalato) borate.
The organic solvent is one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, vinylene carbonate, fluoroethylene carbonate, diethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1, 3-dioxolane, tetrahydrofuran and methyltetrahydrofuran.
The second additive is one or more of lithium nitrate, lithium perchlorate, lithium sulfate, lithium carbonate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluoro (oxalato) borate, lithium tetrafluoroborate and lithium bis (oxalato) borate.
In some embodiments of the invention, the cyano-containing lithium salt is used at least as a lithium salt electrolyte in an amount of 0.01 to 80% by mass of the lithium battery electrolyte.
In some embodiments of the invention, the lithium battery electrolyte further comprises an organic solvent, an additive, and optionally a second lithium salt electrolyte. In terms of quality, the cyano-containing lithium salt is used as a lithium salt electrolyte, and other components which can be used as the lithium salt electrolyte are not excluded from the electrolyte.
Wherein the organic solvent is one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, vinylene carbonate, fluoroethylene carbonate, diethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1, 3-dioxolane, tetrahydrofuran and methyltetrahydrofuran.
The additive is one or more of lithium nitrate, lithium perchlorate, lithium sulfate, lithium carbonate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluoro (oxalato) borate, lithium tetrafluoroborate and lithium bis (oxalato) borate.
The second lithium salt electrolyte is one or more of lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluorooxalato borate, lithium tetrafluoroborate and lithium bis (oxalato) borate.
Further, the present inventors have found that the resulting electrolyte, when the cyano-containing lithium salt is used in combination with lithium nitrate, further improves the performance of the battery, regardless of whether it is used as a lithium salt electrolyte or an additive.
In some embodiments of the invention, the concentration of the lithium salt electrolyte in the electrolyte is 0.01 to 5mol/L.
In some embodiments of the invention, the additives other than the cyano-containing lithium salt in the electrolyte comprise within 20% of the total mass of the electrolyte.
In a preferred embodiment of the present invention, the cyano-containing lithium salt is used as an additive, the lithium salt electrolyte is lithium bis-fluorosulfonyl imide, the organic solvent is ethylene glycol dimethyl ether, and the second additive is lithium nitrate.
In another preferred embodiment of the present invention, the cyano-containing lithium salt is used as a lithium salt electrolyte, the organic solvent is ethylene glycol dimethyl ether and fluorinated ethylene carbonate, and the additive is lithium nitrate.
In a fourth aspect, the present invention provides a lithium battery comprising the above lithium battery electrolyte containing a cyano lithium salt according to the present invention. The shape of the lithium battery is not limited, and the lithium battery can be a cylinder, an aluminum shell, a plastic shell or a soft package shell.
Further, the lithium battery includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode. The positive electrode can be lithium iron phosphate, lithium cobalt oxide, lithium manganate, lithium nickel manganate or ternary positive electrode material, preferably ternary positive electrode material, such as LiNi x Co y Mn 1-x-y O 2 Wherein 0 < x < 1,0 < y < 1, and x+y < 1. The negative electrode is a lithium metal negative electrode or a graphite negative electrode. The diaphragm is a polypropylene or polyethylene film.
The invention provides a cyano-containing lithium salt, a preparation method thereof, lithium battery electrolyte and a lithium battery, wherein nitrogen atoms with coordination ability in cyano groups are utilized to coordinate with transition metals in a positive electrode material in the rest and charging processes of the lithium battery, so that the positive electrode material is stabilized, dissolution of the transition metals and side reactions catalyzed by active sites of the transition metals are inhibited, and CEI film formation is indirectly optimized, so that a positive electrode interface is effectively passivated, the high-voltage resistance, the cycle stability and the rate capability of the battery are improved, and the equipment market with higher requirements on the aspects of quick charge and long cycle life of the lithium battery can be further widened.
Drawings
FIG. 1 is a normal temperature cycle rate chart of NCM811/Li half batteries prepared in example 1 and comparative example 1;
FIG. 2 is a graph showing the cycle performance of NCM811/Li half batteries prepared in example 1, example 6 and comparative example 1;
FIG. 3 is a graph showing the cycle performance of NCM811/Li full cells prepared in example 1 and comparative example 1.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Unless specifically indicated, the technical means used in the embodiments of the present invention are conventional means well known to those skilled in the art.
The organic solvent, lithium salt electrolyte and additive used in the examples and comparative examples of the present invention are all battery grade, and the cyano-containing lithium salt prepared by the present invention is subjected to multi-step purification and severe drying.
The electrolyte formulation conditions in the following examples were operated in an argon glove box filled with 99.999% purity, with less than 0.1ppm moisture in the glove box, and at room temperature.
Synthesis example 1
The present embodiment provides a cyano-containing lithium salt having the following structural formula:
the preparation method comprises the following steps:
in the first step, triflyl chloride is dissolved in acetonitrile-water (volume ratio 10:1), and potassium carbonate is added after the sample is completely dissolved, and then stirred at room temperature. And (3) dissolving the nitrile amine in acetonitrile, slowly dripping the nitrile amine into the solution after homogeneous phase is formed, reacting at 25 ℃ for 18 hours, filtering the obtained mixture after the reaction, and performing rotary evaporation on the obtained filtrate to obtain a potassium salt intermediate product.
And secondly, dissolving the intermediate product in acetonitrile, and adding lithium tetrafluoroborate for substitution reaction to obtain a target product, wherein the reaction temperature is 25 ℃ and the reaction time is 5 hours. The specific reaction formula is as follows:
characterization data are as follows: 19 F-NMR(376MHz,DMSO)δ-78.00；C 2 F 3 N 2 O 2 S - HRMS (ESI, M/z) M - Theoretical value: 173.0898; test value: 173.0868.
synthesis example 2
The present embodiment provides a cyano-containing lithium salt having the following structural formula:
the preparation method comprises the following steps:
in the first step, triflyl chloride is dissolved in acetonitrile-water (volume ratio 10:1), and potassium carbonate is added after the sample is completely dissolved, and then stirred at room temperature. Aminoacetonitrile is additionally dissolved in acetonitrile, and slowly added into the solution after homogeneous phase is formed, the reaction temperature is 25 ℃, the reaction time is 24 hours, the obtained mixture is filtered after the reaction, and the obtained filtrate is distilled to obtain a potassium salt intermediate product.
And secondly, dissolving the intermediate product in acetonitrile, and adding lithium tetrafluoroborate for substitution reaction to obtain a target product, wherein the reaction temperature is 10 ℃ and the reaction time is 6 hours. The specific reaction formula is as follows:
characterization data are as follows: 19 F-NMR(376MHz,DMSO)δ-77.76； 1 H-NMR(400MHz,DMSO)δ2.07；C 3 H 2 F 3 N 2 O 2 S - HRMS (ESI, M/z) M - Theoretical value: 186.9795; test value: 186.9765.
synthesis example 3
The present embodiment provides a cyano-containing lithium salt having the following structural formula:
the preparation method comprises the following steps:
in the first step, the sulfonyl chloride reagent is dissolved in acetonitrile-water (volume ratio 10:1), and after the sample is completely dissolved, potassium carbonate is added, and then the mixture is stirred at room temperature. Aminoacetonitrile is additionally dissolved in acetonitrile, and slowly added into the solution after homogeneous phase is formed, the reaction temperature is 25 ℃, the reaction time is 24 hours, the obtained mixture is filtered after the reaction, and the obtained filtrate is distilled to obtain a potassium salt intermediate product.
And secondly, dissolving the intermediate product in acetonitrile, and adding lithium tetrafluoroborate for displacement reaction to obtain a target product, wherein the reaction temperature is 25 ℃ and the reaction time is 24 hours. The specific reaction formula is as follows:
characterization data are as follows: 1 H-NMR(400MHz,DMSO)δ3.84(t,2H),3.62-3.58(m,8H),3.37-3.35(m,5H)；C 3 H 2 F 3 N 2 O 2 S - HRMS (ESI, M/z) M - Theoretical value: 251.0707; test value: 251.0735.
electrolyte example 1
The present example provides a lithium battery electrolyte comprising the above cyano-containing lithium salt compound (II), which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 14g of lithium nitrate, 36g of the lithium salt compound (II) and 1000mL of ethylene glycol dimethyl ether are taken and stirred until a uniform, clear and transparent solution is obtained.
Electrolyte example 2
The present example provides a lithium battery electrolyte comprising the above cyano-containing lithium salt compound (II), which is formulated as follows:
in a glove box filled with argon, 287g of lithium bistrifluoromethane sulfonyl imide, 21g of lithium perchlorate, 36g of the lithium salt compound (II) and 1000mL of ethylene glycol dimethyl ether are taken and stirred to be uniform, clear and transparent solution.
Electrolyte example 3
The present example provides a lithium battery electrolyte comprising the above cyano-containing lithium salt compound (II), which is formulated as follows:
180g of the lithium salt compound (II), 14g of lithium nitrate and 1000mL of tetraethylene glycol dimethyl ether are taken in a glove box filled with argon, and the mixture is stirred until a uniform, clear and transparent solution is obtained.
Electrolyte example 4
The present embodiment provides a lithium battery electrolyte comprising the above cyano-containing lithium salt compound (III), which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 14g of lithium nitrate, 39g of the lithium salt compound (III) and 1000mL of tetraethyleneglycol dimethyl ether are taken and stirred until a uniform, clear and transparent solution is obtained.
Electrolyte example 5
The present embodiment provides a lithium battery electrolyte comprising the above cyano-containing lithium salt compound (IV), which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 14g of lithium nitrate, 52g of the lithium salt compound (IV) and 1000mL of tetraethyleneglycol dimethyl ether are taken and stirred until a uniform, clear and transparent solution is obtained.
Electrolyte example 6
The present example provides a lithium battery electrolyte comprising the above cyano-containing lithium salt compound (II), which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 29g of lithium difluorooxalato borate, 36g of the lithium salt compound (II) and 1000mL of ethylene glycol dimethyl ether are taken and stirred until a uniform clear and transparent solution is obtained.
Electrolyte comparative example 1
This comparative example provides a lithium battery electrolyte, which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 14g of lithium nitrate and 1000mL of ethylene glycol dimethyl ether are taken and stirred until a uniform clear and transparent solution is obtained.
Electrolyte comparative example 2
This comparative example provides a lithium battery electrolyte, which is formulated as follows:
in a glove box filled with argon, 187g of lithium bis (fluorosulfonyl) imide and 1000mL of ethylene glycol dimethyl ether are taken and stirred until a uniform clear solution is obtained.
Electrolyte comparative example 3
This comparative example provides a lithium battery electrolyte, which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 14g of lithium nitrate, 36g of 1-cyano-N, N- (dimethyl) ethylamine (DMAPN) and 1000mL of ethylene glycol dimethyl ether are taken and stirred until a uniform, clear and transparent solution is obtained.
Electrolyte comparative example 4
This comparative example provides a lithium battery electrolyte, which is formulated as follows:
in a glove box filled with argon, 187g of lithium difluorosulfimide, 14g of lithium nitrate, 36g of lithium hexafluorophosphate and 1000mL of ethylene glycol dimethyl ether are taken and stirred to be a uniform, clear and transparent solution.
Performance testing
The electrolyte prepared in each example and comparative example was assembled into a battery and then subjected to cycle performance test as follows:
by LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811) as positive electrode, lithium sheet as negative electrode, aluminum foil as positive current collector, celgard2325 diaphragm, button half cell or full cell assembly in glove box, standing for 24 hr, and testing. Activating the battery at room temperature and constant temperature of 25 ℃ at a rate of 1/5 ℃ and 3 times of charge and discharge between 3.0V and 4.3V, then charging and discharging at different rates of 1/2C,1C,2C,5C and 10C, testing the capacity at different multiplying powers, and calculating the capacity retention rate, wherein the result is shown in a table 1 (half cell); charge and discharge cycles were performed at a rate of 0.5C at room temperature of 25℃ and the test results are shown in table 2 (full cell).
TABLE 1
TABLE 2
Note that: the capacity of 0 in comparative example 2 means that the electrolyte cannot be circulated under high pressure because of poor oxidation resistance.
FIG. 1 is a graph showing the normal temperature rate performance of NCM811/Li half batteries prepared in example 1 and comparative example 1; FIG. 2 is a graph showing the cycle performance of NCM811/Li half batteries prepared in example 1, example 6 and comparative example 1; FIG. 3 is a graph showing the cycle performance at normal temperature of the NCM811/Li full cells prepared in example 1 and comparative example 1.
As can be seen from tables 1 to 2 and fig. 1 to 3, the electrolyte prepared in the examples of the present invention has significantly better capacity retention than the comparative examples when charge and discharge cycles are performed at different magnifications at room temperature, which means that the cyano lithium salt provided in the present invention can significantly improve the cycle stability of the battery and obtain excellent high magnifications and long cycle life. Moreover, as can be seen from fig. 2, the combination effect of the cyano-containing lithium salt and lithium nitrate of the present invention is more excellent.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A cyano lithium-containing salt having the structure of formula I:
wherein Z is 1 、Z 2 Identical or different, each independently selected from single bond, - (CH) 2 ) x -、-(CH 2 CH 2 O) x -、-(CXH) x -、-(CX 2 ) x -、-(BH) x -、-(SiH 2 ) x One or more of-, sulfinyl, sulfonyl; x and y are integers from 0 to 10, and X=F, cl, br or I;
r is selected from one of fluorine atom, chlorine atom, bromine atom, iodine atom, C1-C10 haloalkyl, C1-C10 alkoxy, C2-C10 alkenyloxy, C2-C10 alkynyloxy, cyano, phenyl, fluorophenyl, trimethylsilyl, trifluoromethyl silyl, cyclotriphosphazene, fluorocyclotriphosphazene, isocyanate, lithium and C1-C10 alkyl.
2. The cyano-containing lithium salt of claim 1 wherein said cyano-containing lithium salt structure comprises a strong electron withdrawing capability, -SO 2 CF 2 -S (=o) or a stronger ligand ability 2 -(CH 2 CH 2 O) 3 -CH 3 and-CN groups having complexing ability;
preferably Z 1 Is a single bond or-CH 2 -，-Z 2 -R is-S (=o) 2 CF 3 or-S (=o) 2 -(CH 2 CH 2 O) 3 -CH 3 。
3. A process for the preparation of a cyano-containing lithium salt as claimed in claim 1 or 2, comprising the steps of:
R-Z 2 -Cl and H 2 N-Z 1 And (3) carrying out a reaction on CN in the presence of potassium carbonate to obtain a potassium salt intermediate product, dissolving the potassium salt intermediate product in acetonitrile, and adding lithium tetrafluoroborate for a displacement reaction to obtain a target product.
4. A lithium battery electrolyte characterized by comprising the cyano-containing lithium salt of claim 1 or 2 as a lithium salt electrolyte and/or additive.
5. The lithium battery electrolyte according to claim 4, wherein the cyano-containing lithium salt is used as an additive only in an amount of 20% or less by mass of the lithium battery electrolyte.
6. The lithium battery electrolyte of claim 5, further comprising a lithium salt electrolyte, an organic solvent, and optionally a second additive;
preferably, the lithium salt electrolyte is one or more of lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluorooxalato borate, lithium tetrafluoroborate, and lithium bis (oxalato) borate;
the organic solvent is one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, vinylene carbonate, fluoroethylene carbonate, diethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1, 3-dioxolane, tetrahydrofuran and methyltetrahydrofuran;
the second additive is one or more of lithium nitrate, lithium perchlorate, lithium sulfate, lithium carbonate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluoro (oxalato) borate, lithium tetrafluoroborate and lithium bis (oxalato) borate.
7. The lithium battery electrolyte according to claim 4, wherein the cyano-containing lithium salt is used at least as a lithium salt electrolyte in an amount of 20 to 80% by mass of the lithium battery electrolyte.
8. The lithium battery electrolyte of claim 7, further comprising an organic solvent, an additive, and optionally a second lithium salt electrolyte;
preferably, the organic solvent is one or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methylethyl carbonate, propylene carbonate, vinylene carbonate, fluoroethylene carbonate, diethyl ether, ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1, 3-dioxolane, tetrahydrofuran and methyltetrahydrofuran;
the additive is one or more of lithium nitrate, lithium perchlorate, lithium sulfate, lithium carbonate, lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluoro (oxalato) borate, lithium tetrafluoroborate and lithium bis (oxalato) borate;
the second lithium salt electrolyte is one or more of lithium bis (fluorosulfonyl) imide, lithium bis (trifluoromethylsulfonyl) imide, lithium hexafluorophosphate, lithium trifluoromethylsulfonate, lithium difluorooxalato borate, lithium tetrafluoroborate and lithium bis (oxalato) borate.
9. A lithium battery comprising the lithium battery electrolyte of any one of claims 4-8.
10. The lithium battery of claim 9, wherein the lithium battery comprises a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode;
preferably, the positive electrode is lithium iron phosphate, lithium cobalt oxide, lithium manganate, lithium nickel manganate or ternary positive electrode material, more preferably ternary positive electrode material;
the negative electrode is a lithium metal negative electrode or a graphite negative electrode;
the diaphragm is a polypropylene or polyethylene film.
CN202310448698.2A 2023-04-24 2023-04-24 Cyano-containing lithium salt, preparation method thereof, lithium battery electrolyte and lithium battery Pending CN116621743A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117638247A (en) * 2024-01-25 2024-03-01 江苏丰山全诺新能源科技有限公司 Functional additive for high-voltage lithium ion battery and application thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117638247A (en) * 2024-01-25 2024-03-01 江苏丰山全诺新能源科技有限公司 Functional additive for high-voltage lithium ion battery and application thereof
CN117638247B (en) * 2024-01-25 2024-04-09 江苏丰山全诺新能源科技有限公司 Functional additive for high-voltage lithium ion battery and application thereof

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