CN115706255A

CN115706255A - Non-aqueous electrolyte and battery

Info

Publication number: CN115706255A
Application number: CN202110910490.9A
Authority: CN
Inventors: 向书槐; 易洋; 胡时光
Original assignee: Shenzhen Capchem Technology Co Ltd
Current assignee: Shenzhen Capchem Technology Co Ltd
Priority date: 2021-08-09
Filing date: 2021-08-09
Publication date: 2023-02-17
Also published as: WO2023016412A1

Abstract

In order to overcome the problems of nonuniform surface thickness, poor high-temperature stability, lower ionic conductivity and higher impedance of an SEI film in the conventional battery, the invention provides a nonaqueous electrolyte, which comprises a solvent, electrolyte salt and a compound shown in a structural formula 1:

Description

Non-aqueous electrolyte and battery

Technical Field

The invention belongs to the technical field of secondary batteries, and particularly relates to a non-aqueous electrolyte and a battery.

Background

In various energy storage devices containing metals or metals and ionic composites thereof as negative and positive materials, such as lithium ion batteries, various additives play a very important role in the performance of the energy storage devices. Film-forming additives are of particular importance. For example, in a lithium ion battery, the film-forming additive performs a redox reaction in preference to the electrolyte to form a layer of solid electrolyte film near an electrode, the negative electrode is called an SEI film, and the positive electrode is often called a CEI film, so that the film-forming additive can play a role in slowing down the reaction between the electrolyte and an electrode material, regulating the permeability of lithium ions, reducing the electronic conductivity and the like, thereby improving the high-low temperature and cycle performance of the battery. However, the SEI film formed by the existing additive has the defects of uneven film surface thickness, poor high-temperature stability, low lithium ion conductivity, high impedance and the like, and has adverse effects on the service life of the battery and high-rate discharge.

Disclosure of Invention

The invention provides a non-aqueous electrolyte and a battery, aiming at the problems of non-uniform surface thickness, poor high-temperature stability, lower ionic conductivity and higher impedance of an SEI film in the conventional battery.

The technical scheme adopted by the invention for solving the technical problems is as follows:

in one aspect, the present invention provides a nonaqueous electrolytic solution comprising a solvent, an electrolyte salt, and a compound represented by structural formula 1:

wherein z is selected from 0 or 1; m and c are independently selected from any natural number of 1-3; p is any natural number from 0 to 3;

when z =0, n =1; when z =1, n =0 or 1;

E ₁ 、E ₂ each independently selected from the group consisting of five-membered ring cyclic carbonate group and derivatives thereof, five-membered ring cyclic sulfite group and derivatives thereof, five-membered ring cyclic sulfate group and derivatives thereof, five-membered ring cyclic sulfonate group and derivatives thereof or five-membered ring sulfinate group and derivatives thereof, E ₁ 、E ₂ May be the same or different;

a is selected from halogen, lithium, sodium, C1-C4 halogenated hydrocarbon groups, cyclic carbonate groups and derivatives thereof, cyclic sulfite groups and derivatives thereof, cyclic sulfate groups and derivatives thereof, cyclic sulfonate groups and derivatives thereof or cyclic sulfinate groups and derivatives thereof.

Optionally, E ₁ 、E ₂ Each independently selected from the group consisting of:

optionally, when z =0, a is selected from a cyclic carbonate group and derivatives thereof, a cyclic sulfite group and derivatives thereof, a cyclic sulfate group and derivatives thereof, a cyclic sulfonate group and derivatives thereof, or a cyclic sulfinate group and derivatives thereof;

when z =1, a is selected from halogens, lithium, sodium, halogenated hydrocarbon groups of C1 to C4, cyclic carbonate groups and derivatives thereof, cyclic sulfite groups and derivatives thereof, cyclic sulfate groups and derivatives thereof, cyclic sulfonate groups and derivatives thereof, or cyclic sulfinate groups and derivatives thereof.

Optionally, m, c are the same, and E ₁ 、E ₂ The same is true.

Optionally, m, c and p are the same, and E ₁ 、E ₂ The same is true.

Optionally, a is selected from the group represented by structural formula 2 or structural formula 3:

wherein a, b are natural numbers and a + b =1 or 2; d =1 or 2, when d =2, Y is a sulfur atom; when d =1, Y is a sulfur atom or a carbon atom;

wherein i and k are natural numbers and i + k =1 or 2 or 3,j =1 or 2.

Optionally, the compound shown in the structural formula 1 is selected from one or more of the following compounds:

optionally, the addition amount of the compound shown in the structural formula 1 is 0.05-10% based on 100% of the total mass of the nonaqueous electrolytic solution.

Optionally, the electrolyte salt is selected from LiPF ₆ 、LiBOB、LiDFOB、LiPO ₂ F ₂ 、LiBF ₄ 、LiSbF ₆ 、LiAsF ₆ 、LiN(SO ₂ CF ₃ ) ₂ 、LiN(SO ₂ C ₂ F ₅ ) ₂ 、LiC(SO ₂ CF ₃ ) ₃ 、LiN(SO ₂ F) ₂ 、LiClO ₄ 、LiAlCl ₄ 、LiCF ₃ SO ₃ 、Li ₂ B ₁₀ Cl ₁₀ And a lower aliphatic carboxylic acid lithium salt.

Optionally, the nonaqueous electrolyte further comprises an auxiliary additive, wherein the auxiliary additive comprises at least one of a cyclic sulfate compound, a sultone compound, a cyclic carbonate compound, an unsaturated phosphate compound and a nitrile compound;

preferably, the cyclic sulfate compound is at least one selected from vinyl sulfate, allyl sulfate or vinyl methyl sulfate;

the sultone compounds are selected from at least one of 1,3-propane sultone, 1,4-butane sultone or 1,3-propylene sultone;

the cyclic carbonate compound is at least one of vinylene carbonate, ethylene carbonate, fluoroethylene carbonate or a compound shown in a structural formula 4,

in the structural formula 4, R ₂₁ 、R ₂₂ 、R ₂₃ 、R ₂₄ 、R ₂₅ 、R ₂₆ Each independently selected from hydrogen atom, halogenOne of an element atom and a C1-C5 group;

the unsaturated phosphate ester compound is selected from at least one of compounds shown in a structural formula 5:

in the structural formula 5, R ₃₁ 、R ₃₂ 、R ₃₂ Each independently selected from C1-C5 saturated alkyl, unsaturated alkyl, halogenated alkyl, -Si (C) _m H _2m+1 ) ₃ M is a natural number of 1 to 3, and R ₃₁ 、R ₃₂ 、R ₃₃ At least one of them is an unsaturated hydrocarbon group;

the nitrile compound includes one or more of succinonitrile, glutaronitrile, ethylene glycol bis (propionitrile) ether, hexanetrinitrile, adiponitrile, pimelitrile, suberonitrile, nonanedionitrile, and decanedionitrile.

In another aspect, the present invention provides a battery comprising a positive electrode, a negative electrode, and the nonaqueous electrolytic solution described above.

According to the nonaqueous electrolytic solution provided by the invention, the inventor speculates that the compound shown in the structural formula 1 is used as a film forming additive, phosphate is used as a central group, at least two five-membered ring structures are externally connected, and the possibility of generating at least two lithium salts in the same molecule is provided according to different requirements. When the group is not removed, the five-membered ring structure can be opened into a ring to form lithium salt (such as lithium sulfate, lithium sulfite, lithium carbonate and the like), or more than two five-membered ring structures all participate in the reaction to generate an SEI film with a cross-linking structure, so that the stability of the film is enhanced, and the service life and the cycle performance of the battery are improved; if one or two groups are removed from the compound shown in the structural formula 1, lithium phosphate containing organic chain segments can be formed in the SEI film and doped in other types of inorganic lithium salts. Meanwhile, the compound shown in the structural formula 1 is a phosphate, phosphite ester compound or phosphonate compound which is formed by taking a phosphorus atom as a central atom. The probability of stepwise leaving of a group directly connected with phosphorus of the compound is far greater than the probability of leaving simultaneously, and the leaving capability of the compound becomes relatively difficult along with the reduction of substituents, so that the probability of forming an SEI film containing an organic-inorganic salt crosslinking structure and the existence time of the SEI film are increased, the stability and the durability of an SEI interface are improved, and the high temperature and the cycle performance of the SEI interface are optimized. The structure can reduce the probability of forming a large-area crystal structure by a single film-forming additive, form small crystal grains to interact with organic matters, have high flexibility, and increase the lithium ion activity on the surface of the crystal, thereby improving the lithium conductivity of the SEI film, improving the structural strength of the SEI film, and finally achieving the comprehensive advantages of improving the discharge efficiency of the battery, the normal-temperature cycle performance, the high-temperature cycle performance, the low-temperature cycle performance and the like.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects solved by the present invention more apparent, the present invention is further described in detail below with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

One embodiment of the present invention provides a nonaqueous electrolytic solution, including a solvent, an electrolyte salt, and a compound represented by structural formula 1:

when z =0, n =1; when z =1, n =0 or 1;

E ₁ 、E ₂ each independently selected from the group consisting of a five-membered ring carbonate group and derivatives thereof, a five-membered ring sulfite group and derivatives thereof, a five-membered ring sulfate group and derivatives thereof, a five-membered ring sulfonate group and derivatives thereof or a five-membered ring sulfinate group and derivatives thereof, E ₁ 、E ₂ May be the same or different;

a is selected from halogen, lithium, sodium, C1-C4 halogenated hydrocarbon groups, cyclic carbonate groups and derivatives thereof, cyclic sulfite groups and derivatives thereof, cyclic sulfate groups and derivatives thereof, cyclic sulfonate groups and derivatives thereof or sulfinate groups and derivatives thereof.

According to the nonaqueous electrolytic solution provided by the invention, the inventor speculates that the compound shown in the structural formula 1 is used as a film forming additive, phosphate is used as a central group, at least two five-membered ring structures are externally connected, and the possibility of generating at least two lithium salts in the same molecule is provided according to different requirements. When the group is not removed, the five-membered ring structure can be formed into lithium salt (such as lithium sulfate, lithium sulfite, lithium carbonate and the like) by ring formation, or more than two five-membered ring structures participate in the reaction to generate an SEI film with a cross-linking structure, so that the stability of the film is enhanced, and the service life and the cycle performance of the battery are improved; if one or two groups are removed from the compound shown in the structural formula 1, lithium phosphate containing organic chain segments can be formed in the SEI film and doped in other types of inorganic lithium salts. Meanwhile, the compound shown in the structural formula 1 is a phosphate ester, phosphite ester compound or phosphonate compound which is formed by taking a phosphorus atom as a central atom. The probability of stepwise leaving of a group directly connected with phosphorus of the compound is far greater than the probability of leaving simultaneously, and the leaving capability of the compound becomes relatively difficult along with the reduction of substituents, so that the probability of forming an SEI film containing an organic-inorganic salt crosslinking structure and the existence time of the SEI film are increased, the stability and the durability of an SEI interface are improved, and the high temperature and the cycle performance of the SEI interface are optimized. The structure can reduce the probability of forming a large-area crystal structure by a single film-forming additive, form small crystal grains to interact with organic matters, have high flexibility, and increase the lithium ion activity on the surface of the crystal, thereby improving the lithium conductivity of the SEI film, improving the structural strength of the SEI film, and finally achieving the comprehensive advantages of improving the discharge efficiency of the battery, the normal-temperature and high-low temperature cycle performance and the like.

In the description of the present invention, "cyclic carbonate group and derivatives thereof" refer to a group containing one or more carbons of a cyclic carbon chain substituted with a carbonate group, and a group in which one or more hydrogen atoms of the cyclic carbon chain are substituted, and the substituted group may be a hydrocarbon group, a halogen, a halogenated hydrocarbon group, etc. "cyclic sulfite groups and derivatives thereof", "cyclic sulfate groups and derivatives thereof", "cyclic sulfonate groups and derivatives thereof" and "cyclic sulfinate groups and derivatives thereof" are to be understood in this definition.

Examples of the halogen include F, cl, br and I.

As the above-mentioned halogenated hydrocarbon group, at least one hydrogen atom in the hydrocarbon group is substituted with a halogen.

In a preferred embodiment, E ₁ 、E ₂ Each independently selected from the group consisting of:

in some embodiments, when z =0, a is selected from a cyclic carbonate group and derivatives thereof, a cyclic sulfite group and derivatives thereof, a cyclic sulfate group and derivatives thereof, a cyclic sulfonate group and derivatives thereof, or a cyclic sulfinate group and derivatives thereof;

when z =1, a is selected from halogen, lithium, sodium, a halogenated hydrocarbon group of C1 to C4, a cyclic carbonate group and derivatives thereof, a cyclic sulfite group and derivatives thereof, a cyclic sulfate group and derivatives thereof, a cyclic sulfonate group and derivatives thereof, or a cyclic sulfinate group and derivatives thereof. When substituted, the halogenated hydrocarbon group is preferably selected from fluorinated hydrocarbon groups.

In a preferred embodiment, m, c are the same, and E ₁ 、E ₂ The same is true.

In a preferred embodiment, m, c and p are all the same, and E ₁ 、E ₂ The same is true.

In a preferred embodiment, A is selected from the group represented by structural formula 2 or structural formula 3:

wherein i, k are natural numbers and i + k =1 or 2 or 3,j =1 or 2.

In a preferred embodiment, when z =0, a is selected from a group represented by structural formula 2 or a group represented by structural formula 3;

when z =1, a is selected from halogen, lithium, sodium, a halogenated hydrocarbon group of C1 to C4, a group represented by structural formula 2, or a group represented by structural formula 3.

The invention is illustrated below by specific compounds:

(1) When z =0,n =1,m = c =1,a is selected from the group represented by structural formula 2 or the group represented by structural formula 3, as an example, the compound represented by structural formula 1 may be selected from:

(2) When z =1,n =1,m = c =1,p =1,a is selected from the group represented by structural formula 2 or the group represented by structural formula 3, the compound represented by structural formula 1 may be selected from:

(3) When z =1,n =0,m = c =1,p =1,a is selected from the group represented by structural formula 2 or the group represented by structural formula 3, the compound represented by structural formula 1 may be selected from:

(4) When z =0,n =1,m = c =1,p =0 or 1,A is selected from lithium or a fluorinated hydrocarbon group, the compound represented by structural formula 1 may be selected from:

(5) When z =1,n =1,m = c =1,p =0 or 1,A is selected from fluorine, lithium or a fluorinated hydrocarbon group, as an example, the compound represented by structural formula 1 may be selected from:

the above-mentioned compounds may be used alone or in combination of two or more.

The method for preparing the compound of formula 1 is known to those skilled in the art based on the common general knowledge in the field of chemical synthesis, while knowing the formula. As examples of the invention:

(1) When z =0 or 1,n =1,m = c =1,a is selected from the group represented by structural formula 2 or structural formula 3, the compound represented by structural formula 1 can be prepared by the following method:

phosphorus oxychloride or phosphorus trichloride is adopted to firstly carry out double decomposition reaction with two equivalent weight of a compound 21, a compound 22, a compound 23, a compound 24 or a compound 25 in the presence of an acid-binding agent, and then the compound is mixed with an excessive compound shown in a structural formula 6 or a compound shown in a structural formula 7 in the presence of the acid-binding agent to generate a compound shown in a structural formula 1.

Wherein a, b are natural numbers and a + b =1 or 2; p is selected from any natural number from 0 to 3; d =1 or 2, when d =2, Y is a sulfur atom; when d =1, Y is a sulfur atom or a carbon atom.

Wherein i, k are natural numbers and i + k =1 or 2 or 3; j =1 or 2,p is selected from any natural number from 0 to 3.

(2) When z =0,n =1,m = c =1,a is selected from the group represented by structural formula 2 or structural formula 3, the compound represented by structural formula 1 can be prepared by the following method:

phosphorus trichloride and three equivalent compounds 21, 22, 23, 24 or 25 are subjected to metathesis reaction in the presence of an acid-binding agent to generate an intermediate, and then the intermediate is subjected to rearrangement reaction with a compound shown in a structural formula 8 or a structural formula 9 to generate a compound shown in a structural formula 1.

Wherein a, b are natural numbers and a + b =1 or 2; p is any natural number from 0 to 3; d =1 or 2, and when d =2, Y is a sulfur atom; when d =1, Y is a sulfur atom or a carbon atom.

(3) When z =0 or 1,m = c =1,p =0,a is selected from lithium or sodium, the compound represented by structural formula 1 can be prepared by the following method:

phosphorus oxychloride or phosphorus trichloride is firstly subjected to double decomposition reaction with three equivalent compounds 21, 22, 23, 24 or 25 in the presence of an acid binding agent, and then is subjected to reaction with lithium hydroxide or sodium hydroxide in an organic solvent to generate the compound shown in the structural formula 1.

(4) When z =0 or 1,m = c =1, a is selected from halogenated hydrocarbon groups, the compound represented by structural formula 1 can be prepared by the following method:

phosphorus oxychloride or phosphorus trichloride is subjected to double decomposition reaction with two equivalent compounds 21, 22, 23, 24 or 25 in the presence of an acid-binding agent, and then the phosphorus oxychloride or phosphorus trichloride and an excessive compound shown in a structural formula 10 are subjected to double decomposition reaction in the presence of the acid-binding agent to generate a compound shown in a structural formula 1.

Wherein M is C1-C4 halogenated hydrocarbon group.

(5) When z =0 or 1,n =0,m = c =1,p =0,a is selected from fluorine atoms, the compound represented by structural formula 1 can be prepared by the following method:

phosphorus oxychloride or phosphorus trichloride is firstly subjected to double decomposition reaction with two equivalent amounts of a compound 21, a compound 22, a compound 23, a compound 24 or a compound 25 in the presence of an acid-binding agent, and then is subjected to direct fluorination with equivalent amounts of fluoride salts such as potassium fluoride, cobalt fluoride, cesium fluoride and the like to generate the compound shown in the structural formula 1.

In some embodiments, the compound represented by formula 1 is added in an amount of 0.05 to 10% based on 100% by mass of the total nonaqueous electrolytic solution.

In a preferred embodiment, the compound represented by the formula 1 is added in an amount of 0.1 to 5% based on 100% by mass of the total nonaqueous electrolytic solution.

Specifically, the compound represented by the structural formula 1 may be added in an amount of 0.05%, 0.1%, 0.3%, 0.5%, 0.8%, 1%, 1.4%, 1.9%, 2.1%, 2.3%, 2.8%, 3.2%, 3.7%, 4.0%, 4.5%, 5%, 5.5%, 6.2%, 6.8%, 7.7%, 8.8%, 9.3%, 10%.

When the addition amount of the compound shown in the structural formula 1 is in the range, the high-temperature storage performance of the battery can be effectively improved, and if the addition amount of the compound shown in the structural formula 1 is too small, the performance of the battery is difficult to generate an obvious improvement effect; if the amount of the compound represented by the formula 1 added is too large, the decomposition product may be too large to affect the function of other substances in the electrolyte.

In some embodiments, the electrolyte salt includes one or more of a lithium salt, a sodium salt, a potassium salt, a magnesium salt, a zinc salt, and an aluminum salt. In a preferred embodiment, the electrolyte salt is selected from a lithium salt or a sodium salt.

In a preferred embodiment, the lithium salt is selected from LiPF ₆ 、LiBOB、LiDFOB、LiPO ₂ F ₂ 、LiBF ₄ 、LiSbF ₆ 、LiAsF ₆ 、LiN(SO ₂ CF ₃ ) ₂ 、LiN(SO ₂ C ₂ F ₅ ) ₂ 、LiC(SO ₂ CF ₃ ) ₃ 、LiN(SO ₂ F) ₂ 、LiClO ₄ 、LiAlCl ₄ 、LiCF ₃ SO ₃ 、Li ₂ B ₁₀ Cl ₁₀ And a lower aliphatic carboxylic acid lithium salt. When the electrolyte salt is selected from other salts such as sodium salt, potassium salt, magnesium salt, zinc salt, aluminum salt, etc., lithium in the above lithium salt may be replaced with sodium, potassium, magnesium, zinc, aluminum, etc.

In a preferred embodiment, the sodium salt is selected from sodium perchlorate (NaClO) ₄ ) Sodium hexafluorophosphate (NaPF) ₆ ) Sodium tetrafluoroborate (NaBF) ₄ ) Sodium triflate (NaFSI) and sodium bistrifluoromethylsulfonate (NaTFSI).

In some embodiments, the concentration of the electrolyte salt in the nonaqueous electrolytic solution is 0.1mol/L to 8mol/L. In a preferred embodiment, the concentration of the electrolyte salt in the nonaqueous electrolytic solution is 0.5mol/L to 2.5mol/L. Specifically, the concentration of the electrolyte salt may be 0.5mol/L, 1mol/L, 1.5mol/L, 2mol/L, 2.5mol/L.

In some embodiments, the nonaqueous electrolytic solution further includes an auxiliary additive including at least one of a cyclic sulfate-based compound, a sultone-based compound, a cyclic carbonate-based compound, an unsaturated phosphate-based compound, and a nitrile-based compound;

the cyclic carbonate compound is at least one selected from vinylene carbonate, ethylene carbonate, fluoroethylene carbonate or a compound shown in a structural formula 4,

in the formula 4, R ₂₁ 、R ₂₂ 、R ₂₃ 、R ₂₄ 、R ₂₅ 、R ₂₆ Each independently selected from one of hydrogen atom, halogen atom and C1-C5 group;

in the structural formula 5, R ₃₁ 、R ₃₂ 、R ₃₂ Each independently selected from C1-C5 saturated alkyl, unsaturated alkyl, halogenated alkyl, -Si (C) _m H _2m+1 ) ₃ M is a natural number of 1 to 3, and R ₃₁ 、R ₃₂ 、R ₃₃ At least one of them is an unsaturated hydrocarbon group. Specifically, the unsaturated phosphate ester compound may be at least one of tripropargyl phosphate, dipropargyl methyl phosphate, dipropargyl ethyl phosphate, dipropargyl propyl phosphate, dipropargyl trifluoromethyl phosphate, dipropargyl-2,2,2-trifluoroethyl phosphate, dipropargyl-3,3,3-trifluoropropyl phosphate, dipropargyl hexafluoroisopropyl phosphate, triallyl phosphate, diallyl methyl phosphate, diallyl ethyl phosphate, diallyl propyl phosphate, diallyl trifluoromethyl phosphate, diallyl-2,2,2-trifluoroethyl phosphate, diallyl-3,3,3-trifluoropropyl phosphate, and diallyl hexafluoroisopropyl phosphate.

The nitrile compound comprises one or more of succinonitrile, glutaronitrile, ethylene glycol bis (propionitrile) ether, hexanetricarbonitrile, adiponitrile, pimelonitrile, suberonitrile, nonadinitrile and sebaconitrile.

Unless otherwise specified, in general, any optional auxiliary additive is added to the nonaqueous electrolytic solution in an amount of 0.05 to 10%, preferably in an amount of 0.1 to 5%, more preferably in an amount of 0.1 to 3%. Specifically, the additive amount of any optional substance in the auxiliary additive may be 0.05%, 0.08%, 0.1%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.8%, 3%, 3.2%, 3.5%, 3.8%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 7.8%, 8%, 8.5%, 9%, 9.5%, 10%.

In some embodiments, when the auxiliary additive is selected from fluoroethylene carbonate, the fluoroethylene carbonate is added in an amount of 0.05% to 30% based on 100% by mass of the total mass of the nonaqueous electrolytic solution.

Compared with single addition or combination of other existing additives, when the compound shown in the structural formula 1 and the auxiliary additive are added together in the non-aqueous electrolyte, the compound shows an obvious synergistic improvement effect in the aspect of improving the high-temperature storage performance of the battery, and the condition that the compound shown in the structural formula 1 and the auxiliary additive form a film together on the surface of an electrode can be used for making up the film forming defect of single addition, so that a passivation film which is more stable under a high-temperature condition is obtained.

In a preferred embodiment, the auxiliary additive is selected from vinyl sulfate.

In some embodiments, the solvent includes one or more of an ether-based solvent, a nitrile-based solvent, a carbonate-based solvent, a carboxylate-based solvent, and a sulfone-based solvent.

In some embodiments, the ether-based solvent includes a cyclic ether or a chain ether, preferably a chain ether having 3 to 10 carbon atoms and a cyclic ether having 3 to 6 carbon atoms, and the cyclic ether may be specifically, but not limited to, one or more of 1,3-Dioxolane (DOL), 1,4-Dioxan (DX), crown ether, tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-CH 3-THF), 2-trifluoromethyltetrahydrofuran (2-CF 3-THF); the chain ether may specifically be, but not limited to, dimethoxymethane, diethoxymethane, ethoxymethoxymethane, ethylene glycol di-n-propyl ether, ethylene glycol di-n-butyl ether, diethylene glycol dimethyl ether. Dimethoxymethane, diethoxymethane, and ethoxymethoxymethane, which have low viscosity and can impart high ionic conductivity, are particularly preferable because chain ethers have high solvating ability with lithium ions and can improve ion dissociation properties. The ether compound may be used alone, or two or more thereof may be used in combination in any combination and ratio. The amount of the ether compound to be added is not particularly limited, and is arbitrary within a range not significantly impairing the effect of the high-compaction lithium ion battery of the present invention, and is usually 1% by volume or more, preferably 2% by volume or more, and more preferably 3% by volume or more, and is usually 30% by volume or less, preferably 25% by volume or less, and more preferably 20% by volume or less, based on 100% by volume of the nonaqueous solvent. When two or more ether compounds are used in combination, the total amount of the ether compounds may be within the above range. When the amount of the ether compound added is within the above-mentioned preferable range, the effect of improving the ionic conductivity by increasing the degree of dissociation of lithium ions and lowering the viscosity of the chain ether can be easily secured. In addition, when the negative electrode active material is a carbon material, the co-intercalation phenomenon of the chain ether and the lithium ion can be suppressed, and therefore the input/output characteristics and the charge/discharge rate characteristics can be set to appropriate ranges.

In some embodiments, the nitrile solvent may specifically be, but is not limited to, one or more of acetonitrile, glutaronitrile, malononitrile.

In some embodiments, the carbonate-based solvent includes a cyclic carbonate or a chain carbonate, and the cyclic carbonate may be, but is not limited to, one or more of Ethylene Carbonate (EC), propylene Carbonate (PC), γ -butyrolactone (GBL), butylene Carbonate (BC); the chain carbonate may specifically be, but not limited to, one or more of dimethyl carbonate (DMC), ethyl Methyl Carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC). The content of the cyclic carbonate is not particularly limited and may be any within a range not significantly impairing the effect of the high-compacted lithium ion battery of the present invention, but in the case where one is used alone, the lower limit of the content is usually 3% by volume or more, preferably 5% by volume or more, relative to the total amount of the solvent of the nonaqueous electrolytic solution. By setting this range, it is possible to avoid a decrease in conductivity due to a decrease in the dielectric constant of the nonaqueous electrolytic solution, and to easily bring the large-current discharge characteristic, the stability to the negative electrode, and the cycle characteristic of the nonaqueous electrolytic battery into a favorable range. The upper limit is usually 90% by volume or less, preferably 85% by volume or less, and more preferably 80% by volume or less. Setting this range can improve the oxidation/reduction resistance of the nonaqueous electrolytic solution, and contributes to improvement of stability during high-temperature storage. The content of the chain carbonate is not particularly limited, and is usually 15% by volume or more, preferably 20% by volume or more, and more preferably 25% by volume or more, based on the total amount of the solvent of the nonaqueous electrolytic solution. The volume ratio is usually 90% or less, preferably 85% or less, and more preferably 80% or less. When the content of the chain carbonate is in the above range, the viscosity of the nonaqueous electrolytic solution is easily brought to an appropriate range, the decrease in the ionic conductivity is suppressed, and the content contributes to bringing the output characteristics of the nonaqueous electrolyte battery to a good range. When two or more kinds of chain carbonates are used in combination, the total amount of the chain carbonates may be set to satisfy the above range.

In some embodiments, chain carbonates having a fluorine atom (hereinafter simply referred to as "fluorinated chain carbonates") may also be preferably used. The number of fluorine atoms in the fluorinated chain carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the fluorinated chain carbonate has a plurality of fluorine atoms, the fluorine atoms may be bonded to the same carbon atom or may be bonded to different carbons. Examples of the fluorinated chain carbonate include a fluorinated dimethyl carbonate derivative, a fluorinated ethyl methyl carbonate derivative, and a fluorinated diethyl carbonate derivative.

In some embodiments, the carboxylic ester solvent may be, but is not limited to, one or more of Methyl Acetate (MA), ethyl Acetate (EA), propyl acetate (EP), butyl acetate, propyl Propionate (PP), butyl propionate.

In some embodiments, the sulfone-based solvent includes cyclic sulfones and chain sulfones, but preferably, in the case of cyclic sulfones, compounds having usually 3 to 6 carbon atoms, preferably 3 to 5 carbon atoms, and in the case of chain sulfones, compounds having usually 2 to 6 carbon atoms, preferably 2 to 5 carbon atoms. The amount of the sulfone solvent to be added is not particularly limited, and is arbitrary within a range not significantly impairing the effect of the high-performance lithium ion battery of the present invention, and is usually 0.3% by volume or more, preferably 0.5% by volume or more, and more preferably 1% by volume or more, and is usually 40% by volume or less, preferably 35% by volume or less, and more preferably 30% by volume or less, based on the total amount of the solvent of the nonaqueous electrolytic solution. In the case where two or more sulfone solvents are used in combination, the total amount of the sulfone solvent may be set to satisfy the above range. When the amount of the sulfone solvent added is within the above range, an electrolyte solution having excellent high-temperature storage stability tends to be obtained.

Another embodiment of the present invention provides a battery including a positive electrode, a negative electrode, and the nonaqueous electrolytic solution described above.

Due to the adoption of the non-aqueous electrolyte, the battery can form a passive film with excellent performance on the positive electrode and the negative electrode, thereby effectively improving the high-temperature storage performance and the high-temperature cycle performance of the battery and improving the power characteristic of the battery.

In some embodiments, the battery is a secondary battery, which may be a lithium secondary battery, a potassium secondary battery, a sodium secondary battery, a magnesium secondary battery, a zinc secondary battery, an aluminum secondary battery, or the like.

In a preferred embodiment, the battery is a lithium metal battery, a lithium ion battery, a lithium sulfur battery, a sodium ion battery.

In some embodiments, the positive electrode includes a positive electrode active material layer including a positive electrode active material, the kind and content of the positive electrode active material are not particularly limited and may be selected according to actual needs as long as the positive electrode active material or a conversion-type positive electrode material is capable of reversibly intercalating/deintercalating metal ions (lithium ions, sodium ions, potassium ions, magnesium ions, zinc ions, aluminum ions, etc.).

In a preferred embodiment, the battery is a lithium ion battery, the positive active material of which may be selected from LiFe _1-x’ M’ _x’ PO ₄ 、LiMn _2-y’ M _y’ O ₄ And LiNi _x Co _y Mn _z M _1-x-y-z O ₂ Wherein M ' is selected from one or more of Mn, mg, co, ni, cu, zn, al, sn, B, ga, cr, sr, V or Ti, M is selected from one or more of Fe, co, ni, mn, mg, cu, zn, al, sn, B, ga, cr, sr, V or Ti, and 0 ≤ x ' < 1,0 ≤ y ' ≦ 1,0 ≤ y ≤ 1,0 ≤ x ≤ 1,0 ≤ z ≤ 1, x + y z ≤ 1, and the anode active material can also be selected from one or more of sulfide, selenide and halide. More preferably, the positive active material may be selected from LiCoO ₂ 、LiFePO ₄ 、LiFe _0.8 Mn _0.2 PO ₄ 、LiMn ₂ O ₄ 、LiNi _0.5 Co _0.2 Mn _0.3 O ₂ 、LiNi _0.6 Co _0.2 Mn _0.2 O ₂ 、LiNi _0.8 Co _0.1 Mn _0.1 O ₂ 、LiNi _0.5 Co _0.2 Mn _0.2 Al _0.1 O ₂ 、LiNi _0.5 Co _0.2 Al _0.3 O ₂ One or more of (a).

In a preferred embodiment, the battery is a sodium ion battery, and the positive active material of the battery can be one or more selected from metal sodium, carbon materials, alloy materials, plated metal oxides, plated metal sulfides, phosphorus-based materials, titanate materials and Prussian blue-based materials. The carbon material can be selected from one or more of graphite, soft carbon and hard carbon, the alloy material can be selected from alloy materials consisting of at least two of Si, ge, sn, pb and Sb, the alloy material can also be selected from alloy materials consisting of at least one of Si, ge, sn, pb and Sb and C, and the plated metal is platedThe chemical formula of the oxide and the plated metal sulfide is M1 _x N _y M1 can be selected from one or more of Fe, co, ni, cu, mn, sn, mo, sb and V, N is selected from O or S, the phosphorus-based material can be selected from one or more of red phosphorus, white phosphorus and black phosphorus, and the titanate material can be selected from Na ₂ Ti ₃ O ₇ 、Na ₂ Ti ₆ O ₁₃ 、Na ₄ Ti ₅ O ₁₂ 、Li ₄ Ti ₅ O ₁₂ 、NaTi ₂ (PO ₄ ) ₃ One or more than one of the Prussian blue materials, wherein the molecular formula of the Prussian blue materials is Na _x M[M′(CN) ₆ ] _y ·zH ₂ O, wherein M is a transition metal, M' is a transition metal, 0<x≤2，0.8≤y<1，0<z≤20。

In some embodiments, the positive electrode further comprises a positive electrode current collector, and the positive electrode material layer covers the surface of the positive electrode current collector.

The positive electrode current collector is selected from metal materials capable of conducting electrons, preferably, the positive electrode current collector comprises one or more of Al, ni, tin, copper and stainless steel, and in a more preferred embodiment, the positive electrode current collector is selected from aluminum foil.

In some embodiments, the positive electrode active material layer further includes a positive electrode binder and a positive electrode conductive agent, and the positive electrode active material, the positive electrode binder and the positive electrode conductive agent are blended to obtain the positive electrode active material layer.

The positive binder comprises thermoplastic resins such as polyvinylidene fluoride, copolymers of vinylidene fluoride, polytetrafluoroethylene, copolymers of vinylidene fluoride and hexafluoropropylene, copolymers of tetrafluoroethylene and perfluoroalkyl vinyl ether, copolymers of ethylene and tetrafluoroethylene, copolymers of vinylidene fluoride and trifluoroethylene, copolymers of vinylidene fluoride and trichloroethylene, copolymers of vinylidene fluoride and fluoroethylene, copolymers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, thermoplastic polyimide, polyethylene, polypropylene and the like; an acrylic resin; and styrene butadiene rubber.

The positive electrode conductive agent comprises one or more of conductive carbon black, conductive carbon spheres, conductive graphite, conductive carbon fibers, carbon nanotubes, graphene or reduced graphene oxide.

In some embodiments, the anode includes an anode material layer including an anode active material including one or more of a carbon-based anode, a tin-based anode, a silicon-based anode, a lithium anode, a sodium anode, a potassium anode, a magnesium anode, a zinc anode, and an aluminum anode. The carbon-based negative electrode can comprise graphite, hard carbon, soft carbon, graphene, mesocarbon microbeads and the like; the silicon-based negative electrode may comprise one or more of a silicon material, an oxide of silicon, a silicon-carbon composite material, and a silicon alloy material; the tin-based negative electrode may include tin, tin carbon, tin oxide, tin metal compounds; the lithium negative electrode may include metallic lithium or a lithium alloy. The lithium alloy may specifically be at least one of a lithium silicon alloy, a lithium sodium alloy, a lithium potassium alloy, a lithium aluminum alloy, a lithium tin alloy, and a lithium indium alloy.

In some embodiments, the negative electrode further comprises a negative electrode current collector, and the negative electrode material layer covers the surface of the negative electrode current collector. The material of the negative current collector may be the same as that of the positive current collector, and thus, the description thereof is omitted.

In some embodiments, the negative electrode material layer further includes a negative electrode binder and a negative electrode conductive agent, and the negative electrode active material, the negative electrode binder and the negative electrode conductive agent are blended to obtain the negative electrode material layer. The negative electrode binder and the negative electrode conductive agent may be the same as the positive electrode binder and the positive electrode conductive agent, respectively, and are not described herein again.

In some embodiments, a separator is also included in the battery, the separator being positioned between the positive electrode and the negative electrode.

The diaphragm can be an existing conventional diaphragm, and can be a ceramic diaphragm, a polymer diaphragm, non-woven fabric, an inorganic-organic composite diaphragm and the like, including but not limited to diaphragms such as single-layer PP (polypropylene), single-layer PE (polyethylene), double-layer PP/PE, double-layer PP/PP and three-layer PP/PE/PP.

The present invention is further illustrated by the following examples.

The compounds of formula 1 used in the following examples are as follows:

examples 1 to 14

This example is intended to illustrate the preparation method of the nonaqueous electrolyte and the battery disclosed in the present invention, and includes the following steps:

1) Preparation of nonaqueous electrolyte:

ethylene Carbonate (EC), diethyl carbonate (DEC) and Ethyl Methyl Carbonate (EMC) were mixed at a mass ratio of EC: DEC: EMC =1 ₆ ) To a molar concentration of 1mol/L, additives were added in the amounts by mass shown in examples 1 to 14 in tables 1 to 4, based on 100% by weight of the total weight of the nonaqueous electrolytic solution.

2) Preparing a positive plate:

the positive electrode active material lithium nickel cobalt manganese oxide LiNi was mixed in a mass ratio of 93 _0.5 Co _0.2 Mn _0.3 O ₂ Conductive carbon black Super-P and a binder polyvinylidene fluoride (PVDF), and then dispersed in N-methyl-2-pyrrolidone (NMP) to obtain a positive electrode slurry. And uniformly coating the slurry on two sides of the aluminum foil, drying, rolling and vacuum drying, and welding an aluminum outgoing line by using an ultrasonic welding machine to obtain the positive plate, wherein the thickness of the positive plate is 120-150 mu m.

3) Preparing a negative plate:

the negative electrode active material artificial graphite, conductive carbon black Super-P, binders Styrene Butadiene Rubber (SBR) and carboxymethyl cellulose (CMC) were mixed in a mass ratio of 94. Coating the slurry on two sides of a copper foil, drying, rolling and vacuum drying, and welding a nickel outgoing line by using an ultrasonic welding machine to obtain a negative plate, wherein the thickness of the negative plate is 120-150 mu m.

4) Preparing an electric core:

and placing three layers of diaphragms with the thickness of 20 mu m between the positive plate and the negative plate, then winding the sandwich structure consisting of the positive plate, the negative plate and the diaphragms, flattening the wound body, then placing the flattened wound body into an aluminum foil packaging bag, and baking the flattened wound body in vacuum at 75 ℃ for 48 hours to obtain the battery cell to be injected with liquid.

5) Liquid injection and formation of the battery cell:

and (3) in a glove box with the dew point controlled below-40 ℃, injecting the prepared electrolyte into the battery cell, carrying out vacuum packaging, and standing for 24 hours.

Then the first charge is normalized according to the following steps: charging at 0.05C for 180min, charging at 0.2C to 3.95V, vacuum sealing, charging at 0.2C to 4.2V, standing at room temperature for 24hr, and discharging at 0.2C to 3.0V to obtain LiNi _0.5 Co _0.2 Mn _0.3 O ₂ Artificial graphite lithium ion battery.

Comparative examples 1 to 7

This example is intended to illustrate by comparison the non-aqueous electrolyte and battery methods disclosed in this invention, including most of the operating steps in example 1, except that:

in the preparation of the nonaqueous electrolytic solution, additives were added in the amounts by mass shown in comparative examples 1 to 7 in tables 1 to 4.

Performance testing

The lithium ion batteries prepared in examples 1 to 14 and comparative examples 1 to 7 were subjected to the following performance tests: high temperature storage Performance test

The lithium ion battery after formation is charged to 4.2V at a constant current of 1C at normal temperature, then charged at a constant current and a constant voltage until the current is reduced to 0.05C, then discharged to 3.0V at a constant current of 1C, the initial discharge capacity and the initial battery volume of the battery are measured, then the battery is charged to full charge, stored for 30 days, 60 days and 90 days in an environment of 60 ℃, discharged to 3V at 1C, and the retention capacity and the recovery capacity of the battery are measured. The calculation formula is as follows:

battery capacity retention (%) = retention capacity/initial capacity × 100%;

battery capacity recovery (%) = recovered capacity/initial capacity × 100%.

1. The test results obtained in examples 1 to 8 and comparative examples 1 to 4 are filled in Table 1.

TABLE 1

The test results of comparative examples 1 to 8 and comparative examples 1 to 4 show that, compared with the conventional Vinylene Carbonate (VC), vinyl sulfate (DTD) and 1,3-Propane Sultone (PS), the storage performance of the lithium ion battery at high temperature can be improved more significantly by using the compound represented by the formula 1 provided by the present application as an additive, which indicates that the passivation film formed by the compound represented by the formula 1 has more excellent high-temperature stability.

2. The test results obtained in example 2 and examples 9 to 13 were filled in table 2.

TABLE 2

As can be seen from the results of comparing example 2 with examples 9 to 13, as the addition amount of the compound represented by formula 1 increases, the high-temperature storage performance of the lithium ion battery increases first and then decreases, and particularly, when the addition amount of the compound represented by formula 1 is 0.5 to 5%, the lithium ion battery has the optimal high-temperature storage performance.

3. The test results obtained for example 2, example 14, comparative example 3 and comparative example 5 are filled in table 3.

TABLE 3

As can be seen from the test results of comparative example 2, example 14, comparative example 3 and comparative example 5, compared with the conventional Vinylene Carbonate (VC) and vinyl sulfate (DTD) combined additive, or vinyl sulfate (DTD) alone or the compound shown in formula 1 alone, the battery performance is further improved by combining the compound shown in formula 1 and vinyl sulfate (DTD), which is provided by the present application, and it is demonstrated that the passivation film formed by co-decomposition of the compound shown in formula 1 and vinyl sulfate (DTD) has more excellent high-temperature stability.

4. The test results obtained for example 3, example 6, comparative example 6 and comparative example 7 are filled in table 4.

TABLE 4

The test results of comparative examples 3 and 6 and comparative examples 6 and 7 show that when the compound shown in the formula 1 has two or more cyclic substituents, a cross-linked structure film with strong integrity and stable structure can be formed, so that a passivation film with stable high-temperature performance can be formed.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

1. A nonaqueous electrolytic solution, comprising a solvent, an electrolyte salt, and a compound represented by formula 1:

when z =0, n =1; when z =1, n =0 or 1;

E ₁ 、E ₂ each independently selected from the group consisting of a five-membered ring carbonate group and derivatives thereof, a five-membered ring sulfite group and derivatives thereof, a five-membered ring sulfate group and derivatives thereof, a five-membered ring sulfonate group and derivatives thereof, or a five-membered ring sulfinate group and derivatives thereof, E ₁ 、E ₂ May be the same or different;

2. The nonaqueous electrolytic solution of claim 1, wherein E is ₁ 、E ₂ Each independently selected from one of the following groups:

3. the nonaqueous electrolytic solution of claim 1, wherein m and c are the same, and E is ₁ 、E ₂ The same is true.

4. The nonaqueous electrolytic solution of claim 1, wherein when z =0, a is selected from a cyclic carbonate group and a derivative thereof, a cyclic sulfite group and a derivative thereof, a cyclic sulfate group and a derivative thereof, a cyclic sulfonate group and a derivative thereof, or a cyclic sulfinate group and a derivative thereof;

5. The nonaqueous electrolytic solution of claim 1 or 4, wherein A is selected from a group represented by structural formula 2 or structural formula 3:

wherein a, b are natural numbers and a + b =1 or 2; d =1 or 2, and when d =2, Y is a sulfur atom; when d =1, Y is a sulfur atom or a carbon atom;

wherein i and k are natural numbers and i + k =1 or 2 or 3,j =1 or 2.

6. The nonaqueous electrolytic solution of claim 1, wherein the compound represented by the structural formula 1 is one or more selected from the following compounds:

7. the nonaqueous electrolytic solution of claim 1, wherein the compound represented by the structural formula 1 is added in an amount of 0.05 to 10% based on 100% by mass of the total amount of the nonaqueous electrolytic solution.

8. The nonaqueous electrolytic solution of claim 1, wherein the electrolyte salt is selected from LiPF ₆ 、LiBOB、LiDFOB、LiPO ₂ F ₂ 、LiBF ₄ 、LiSbF ₆ 、LiAsF ₆ 、LiN(SO ₂ CF ₃ ) ₂ 、LiN(SO ₂ C ₂ F ₅ ) ₂ 、LiC(SO ₂ CF ₃ ) ₃ 、LiN(SO ₂ F) ₂ 、LiClO ₄ 、LiAlCl ₄ 、LiCF ₃ SO ₃ 、Li ₂ B ₁₀ Cl ₁₀ And a lower aliphatic carboxylic acid lithium salt.

9. The nonaqueous electrolytic solution of claim 1, further comprising an auxiliary additive, wherein the auxiliary additive comprises at least one of a cyclic sulfate compound, a sultone compound, a cyclic carbonate compound, an unsaturated phosphate compound, and a nitrile compound;

in the structural formula 5, R ₃₁ 、R ₃₂ 、R ₃₂ Each independently of each otherIndependently selected from C1-C5 saturated alkyl, unsaturated alkyl, halogenated alkyl, -Si (C) _m H _2m+1 ) ₃ M is a natural number of 1 to 3, and R ₃₁ 、R ₃₂ 、R ₃₃ At least one of them is an unsaturated hydrocarbon group;

10. A battery comprising a positive electrode, a negative electrode and the nonaqueous electrolytic solution of any one of claims 1 to 9.