Electrolyte, battery and electric device

Abstract

The invention provides an electrolyte, a battery and an electric device. The cycle life of the battery can be prolonged. The electrolyte comprises an organic solvent, the organic solvent comprises a substituted or unsubstituted first nitrogen-containing alkane, a nitrogen atom and a carbon atom in the first nitrogen-containing alkane are connected through a covalent single bond, the nitrogen atom is located between two adjacent carbon atoms, and when the first nitrogen-containing alkane is not substituted, the nitrogen atom and the carbon atom in the first nitrogen-containing alkane are connected through a covalent single bond. The first nitrogen-containing alkane comprises at least one branched alkyl group; when the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane is at least substituted by a halogen atom, and the halogen atom substitution position is a carbon atom position indirectly connected with the nitrogen atom.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and in particular relates to an electrolyte, a battery and an electrical device. Background Art

[0002] Batteries have the characteristics of high capacity and long life, so they are widely used in electronic devices such as mobile phones, laptops, electric vehicles, electric airplanes, electric boats, electric toy cars, electric toy boats, electric toy airplanes and electric tools, etc.

[0003] As the application scope of batteries becomes wider and wider, the requirements for battery performance are becoming increasingly stringent, and the requirements for battery cycle life are gradually increasing. Summary of the invention

[0004] The present application provides an electrolyte, a battery and an electrical device, which can improve the cycle life of the battery.

[0005] An embodiment of the first aspect of the present application provides an electrolyte, the electrolyte comprising an organic solvent, the organic solvent comprising a substituted or unsubstituted first nitrogen-containing alkane, the nitrogen atom in the first nitrogen-containing alkane being connected to a carbon atom by a covalent single bond, and the nitrogen atom being located between two adjacent carbon atoms, wherein when the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane comprises at least one branched alkyl group; when the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane is substituted by at least a halogen atom, and the halogen atom substitution position is a carbon atom position indirectly connected to the nitrogen atom.

[0006] Therefore, according to the electrolyte of the embodiment of the present application, the electrolyte includes a substituted or unsubstituted first nitrogen-containing alkane. The first nitrogen-containing alkane, as an important component of the organic solvent, can effectively promote the formation of a SEI film rich in nitrogen-containing compounds on the surface of the negative electrode plate. The SEI film can effectively passivate the surface of the negative electrode plate, and protect the negative electrode plate, thereby reducing the side reactions between the negative electrode plate and the electrolyte. Moreover, since the SEI film is rich in nitrogen-containing compounds, such compounds can promote the uniform and dense deposition of lithium metal, improve the cycle reversibility of the battery cell, and increase the cycle life of the battery cell. Moreover, the first nitrogen-containing alkane has a strong oxidation resistance. Under a relatively high-voltage system, it can improve the stability of the electrolyte and further improve the cycle life of the battery cell.

[0007] In some embodiments, the unsubstituted first nitrogen-containing alkane includes an unsubstituted nitrogen-containing linear alkane, the unsubstituted nitrogen-containing linear alkane includes a nitrogen-containing straight-chain alkyl group and the branched alkyl group connected to the nitrogen-containing straight-chain alkyl group, the nitrogen atom in the nitrogen-containing straight-chain alkyl group is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms. The above compound can promote the formation of a SEI film rich in nitrogen-containing compounds, improve the interface structure of the negative electrode plate, and is conducive to the uniform and dense deposition of lithium metal; and the compound has a strong oxidation resistance.

[0008] In some embodiments, the unsubstituted nitrogen-containing linear alkane comprises at least one of the compounds represented by formula (I) to the compounds represented by formula (III),

[0009]

[0010] In formula (I),

[0011] R 1 and R 2 Each independently comprises a C1 to C8 alkyl group;

[0012] R 3 including a hydrogen atom or a C1 to C3 alkyl group,

[0013] Among them, when R 3 When hydrogen atoms are included, R 1 and R 2 At least one of the following comprises a branched alkyl group;

[0014] In formula (II),

[0015] R 4 To R 6 Each independently comprises a C1 to C8 alkyl group;

[0016] R 7 and R 8 Each independently includes a hydrogen atom or a C1 to C3 alkyl group,

[0017] Among them, when R 7 and R 8 When all include hydrogen atoms, R 4 To R 6 At least one of the following comprises a branched alkyl group;

[0018] In formula (III),

[0019] R 9 To R 12 Each independently comprises a C1 to C8 alkyl group;

[0020] R 13 To R 15Each independently includes a hydrogen atom or a C1 to C3 alkyl group,

[0021] Among them, when R 13 To R 15 When all include hydrogen atoms, R 9 To R 12 At least one of the alkyl groups includes a branched alkyl group.

[0022] In some embodiments, the compound represented by formula (I) includes at least one of the compounds represented by formula (I-1) to the compounds represented by formula (I-3),

[0023]

[0024] In some embodiments, the compound represented by formula (II) includes at least one of the compounds represented by formula (II-1) to the compounds represented by formula (II-8),

[0025]

[0026]

[0027] In some embodiments, the compound represented by formula (III) includes at least one of the compounds represented by formula (III-1) to the compounds represented by formula (III-4),

[0028]

[0029] In some embodiments, the unsubstituted first nitrogen-containing alkane includes an unsubstituted nitrogen-containing cyclic alkane, the unsubstituted nitrogen-containing cyclic alkane includes a cyclic structure and at least two branched alkyl groups connected to carbon atoms in the cyclic structure, the nitrogen atom in the cyclic structure is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms. The above compound can promote the formation of a SEI film rich in nitrogen-containing compounds, improve the interface structure of the negative electrode plate, and is conducive to the uniform and dense deposition of lithium metal; and the compound has a strong oxidation resistance.

[0030] In some embodiments, the unsubstituted nitrogen-containing cyclic alkane includes a compound represented by formula (IV),

[0031]

[0032] In formula (IV),

[0033] R 16 including C1 to C8 alkyl groups;

[0034] R 17 including a hydrogen atom or a C1 to C3 alkyl group,

[0035] Among them, when R 17 When hydrogen atoms are included, R 17 including branched chain alkyl groups;

[0036] Further optionally, the compound represented by formula (IV) includes at least one of the compound represented by formula (IV-1) and the compound represented by formula (IV-4),

[0037]

[0038] In some embodiments, the unsubstituted nitrogen-containing cyclic alkane includes a compound represented by formula (V),

[0039]

[0040] In formula (IV),

[0041] R 18 and R 19 Each independently comprises a C1 to C8 alkyl group;

[0042] R 20 and R 21 Each independently includes a hydrogen atom or a C1 to C3 alkyl group,

[0043] Among them, when R 20 and R 21 When all include hydrogen atoms, R 18 To R 19 At least one of the following comprises a branched alkyl group;

[0044] Optionally, the compound represented by formula (V) includes at least one of the compounds represented by formula (V-1) to the compounds represented by formula (V-6),

[0045]

[0046] In some embodiments, the substituted nitrogen-containing linear alkane includes at least one halogen atom; alternatively, the substituted nitrogen-containing linear alkane includes at least one of the compounds represented by formula (A) to the compounds represented by formula (C),

[0047]

[0048] In formula (A),

[0049] Q 1 and Q 2 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0050] Q 3 including a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0051] And Q1 To Q 3 At least one of them is substituted by a halogen atom;

[0052] In formula (B),

[0053] Q 4 To Q 6 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0054] Q 7 and Q 8 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0055] And Q 4 To Q 8 At least one of them is substituted by a halogen atom;

[0056] In formula (C),

[0057] Q 9 To Q 12 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0058] Q 13 To Q 15 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0059] And Q 9 To Q 15 At least one of them is substituted by a halogen atom.

[0060] In some embodiments, the compound represented by formula (A) includes at least one of the compounds represented by formula (A-1) to the compounds represented by formula (A-3),

[0061]

[0062] In some embodiments, the compound represented by formula (B) includes at least one of the compounds represented by formula (B-1) to the compounds represented by formula (B-4),

[0063]

[0064] In some embodiments, the compound represented by formula (C) includes at least one of the compounds represented by formula (C-1) to the compounds represented by formula (C-3),

[0065]

[0066] In some embodiments, the substituted first nitrogen-containing alkane includes a substituted nitrogen-containing cyclic alkane, the substituted nitrogen-containing cyclic alkane includes a cyclic structure, the nitrogen atom in the cyclic structure is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, the nitrogen-containing cyclic alkane is substituted with a halogen atom, and the halogen atom substitution position is the carbon atom position indirectly connected to the nitrogen atom.

[0067] In some embodiments, the nitrogen-containing cyclic alkane includes a compound represented by formula (D),

[0068]

[0069] In formula (D),

[0070] Q 16 including substituted or unsubstituted C1 to C8 alkyl groups;

[0071] Q 17 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0072] And, Q 16 and Q 17 At least one of them is substituted by a halogen atom;

[0073] The compound represented by formula (D) includes at least one of the compound represented by formula (D-1) and the compound represented by formula (D-2),

[0074]

[0075] In some embodiments, the nitrogen-containing cyclic alkane includes a compound represented by formula (E),

[0076]

[0077] In formula (E),

[0078] Q 18 and Q 19 including substituted or unsubstituted C1 to C8 alkyl groups;

[0079] Q 20 and Q 21 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0080] And, Q 18 To Q 21 At least one of them is substituted by a halogen atom;

[0081] Optionally, the compound represented by formula (E) includes at least one of the compound represented by formula (E-1) and the compound represented by formula (E-2),

[0082]

[0083] In some embodiments, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the substituted or unsubstituted first nitrogen-containing alkane is greater than or equal to 20% and less than 100%, optionally 40% to 80%, and further optionally 50% to 65%. The use of the first nitrogen-containing alkane having the above mass percentage can improve the ion conductivity of the electrolyte and improve the stability of the electrolyte for the positive and negative electrodes.

[0084] In some embodiments, the electrolyte further includes a second nitrogen-containing alkane, wherein the nitrogen atom in the second nitrogen-containing alkane is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, wherein at least one carbon atom among the carbon atoms adjacent to the nitrogen atom is substituted by a halogen atom.

[0085] Therefore, in the embodiment of the present application, the electrolyte is added with the second nitrogen-containing alkane. On the one hand, since the second nitrogen-containing alkane contains halogen atoms, it can improve the overall oxidation resistance of the electrolyte, which helps to improve the stability of the electrolyte to the positive electrode sheet with an operating voltage of 4V or more. On the other hand, halogen atoms such as fluorine atoms can be decomposed during the lithium metal deposition process to generate fluorine-rich SEI film components, further improving lithium metal deposition and cycle reversibility. Therefore, the second nitrogen-containing alkane and the first nitrogen-containing alkane can play a synergistic role in further improving the reversibility of positive and negative electrode cycles; and the second nitrogen-containing alkane can be well miscible with the first nitrogen-containing alkane, further improving the stability of the electrolyte.

[0086] In some embodiments, the second nitrogen-containing alkane comprises at least one of the compounds represented by formula (1) to the compounds represented by formula (5),

[0087]

[0088] In formula (1),

[0089] M 1 and M 2 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0090] M 3 including a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0091] And M 1 To M 3 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom;

[0092]

[0093] In formula (2),

[0094] M 4 To M 6 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0095] M 7 and M 8 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0096] And M 4 To M 8 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom;

[0097]

[0098] In formula (3),

[0099] M 9 To M 12 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0100] M 13 To M 15 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0101] And M 9 To M 15 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom;

[0102]

[0103] In formula (4),

[0104] M 16 including substituted or unsubstituted C1 to C8 alkyl groups;

[0105] M 17 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0106] And M 16 and M 17 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom;

[0107]

[0108] In formula (5),

[0109] M 18 and M 19 including substituted or unsubstituted C1 to C8 alkyl groups;

[0110] M 20 and M 21 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0111] And M 18 To M 21 At least one of them is substituted by a halogen atom, and the halogen atom is connected to the carbon atom adjacent to the nitrogen atom; further optionally, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the second nitrogen-containing alkane is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%.

[0112] In some embodiments, the electrolyte further comprises a fluorinated solvent, the fluorinated solvent comprising at least one of a fluorinated ether solvent, a fluorinated aromatic solvent, and a fluorinated saturated alkane solvent; optionally, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the fluorinated solvent is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%. On the one hand, since the fluorinated solvent contains halogen atoms such as fluorine atoms, it can improve the overall oxidation resistance of the electrolyte, which helps to improve the stability of the electrolyte to the positive electrode sheet with an operating voltage of more than 4V. On the other hand, halogen atoms such as fluorine atoms can decompose during the lithium metal deposition process to generate fluorine-rich SEI film components, further improving lithium metal deposition and cycle reversibility.

[0113] In some embodiments, the electrolyte further comprises at least one of an ester solvent and an ether solvent. The electrolyte uses a substituted or unsubstituted first sulfur-containing alkane as a main solvent, and is combined with an ester solvent and an ether solvent, which is conducive to dissolving the lithium salt in the solvent and improving the ion conductivity of the electrolyte.

[0114] In some embodiments, the ester solvent includes at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, methyl trifluoroethyl carbonate, ethyl trifluoroethyl carbonate, di(2,2,2-trifluoroethyl) carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl 2,2,2-trifluoroacetate, and ethyl 2,2,2-trifluoroacetate.

[0115] In some embodiments, the ether solvent includes at least one of methyl ether, ethyl ether, propyl ether, butyl ether, methyl ethyl ether, methyl propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, propyl butyl ether, dimethoxymethane, diethoxymethane, dipropoxymethane, dimethoxyethane, dimethoxypropane, diethoxyethane, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane;

[0116] In some embodiments, based on the total mass of the organic solvent in the electrolyte, the total mass percentage of the ester solvent and the ether solvent is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%.

[0117] In some embodiments, the electrolyte further includes a lithium salt, which may include lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ) lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium trifluoromethanesulfonate (LiOTF), lithium difluorophosphate (LiDFP), lithium dioxalatoborate (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium difluorobis(oxalatophosphate) and lithium tetrafluorooxalatophosphate, which can be lithium bis(fluorosulfonyl imide); the above lithium salts can decompose on the surface of the negative electrode to form an SEI film component rich in inorganic fluorine, which is beneficial to the long cycle of lithium metal batteries, and has relatively good oxidation stability, which can improve the cycle life under high voltage working voltage.

[0118] In some embodiments, the molar concentration of the lithium salt is 0.5 mol / L to 4 mol / L, optionally 0.8 mol / L to 2.4 mol / L, and further optionally 1.2 mol / L to 1.8 mol / L.

[0119] In some embodiments, the electrolyte further includes an additive, and the additive includes at least one of propane sultone, vinyl nitrate, vinyl nitrite, tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilane) borate, dimethyl maleic anhydride, and 1,4-diisocyanate; the additive mainly assists SEI film formation, and can further help improve the stability of the positive and negative electrodes of the lithium metal battery and increase the cycle life.

[0120] In some embodiments, based on the total mass of the electrolyte, the mass percentage of the additive is 0% to 5%; optionally 0.5% to 3%.

[0121] In a second aspect, an embodiment of the present application further provides a battery, comprising the electrolyte described in any embodiment of the first aspect of the present application.

[0122] In a third aspect, an embodiment of the present application further provides an electrical device, comprising a battery according to any embodiment of the first aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0123] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without paying creative work.

[0124] Figure 1 This is a schematic diagram of one embodiment of the secondary battery of the present application.

[0125] Figure 2 yes Figure 1 An exploded schematic diagram of an embodiment of a secondary battery.

[0126] Figure 3 It is a schematic diagram of an embodiment of a battery module of the present application.

[0127] Figure 4 It is a schematic diagram of an embodiment of the battery pack of the present application.

[0128] Figure 5 yes Figure 4 An exploded schematic diagram of an embodiment of a battery pack is shown.

[0129] Figure 6 It is a schematic diagram of one embodiment of an electric device including the secondary battery of the present application as a power source.

[0130] The drawings are not necessarily drawn to scale.

[0131] The following are the descriptions of the reference numerals:

[0132] 1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery module;

[0133] 5. Secondary battery; 51. Casing; 52. Electrode assembly;

[0134] 53. Cover plate;

[0135] 6. Electrical equipment. DETAILED DESCRIPTION

[0136] Hereinafter, the embodiments of the electrolyte, battery and electrical device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0137] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0138] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0139] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0140] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, and may be performed sequentially. For example, a method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, a method may also include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0141] The term "alkyl" encompasses straight and branched alkyl groups. For example, the alkyl group may be a C5-C500 alkyl group, a C20-C400 alkyl group, a C1-C50 alkyl group, a C1-C40 alkyl group, a C1-C30 alkyl group, a C1-C20 alkyl group, a C1-C12 alkyl group, a C1-C10 alkyl group, a C1-C6 alkyl group, a C1-C4 alkyl group. In some embodiments, the alkyl group includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, a pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, a hexyl group, a cyclohexyl group, a heptyl group, a cycloheptyl group, an octyl group, a cyclooctyl group, a nonyl group, and a decyl group. In addition, the alkyl group may be optionally substituted. The term "haloalkyl" refers to an alkyl group in which a hydrogen atom is partially or completely replaced by a halogen atom, and the term "halogen atom" refers to a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, and the like.

[0142] The term "hydrogen" refers to 1H (protium, H), 2H (deuterium, D) or 3H (tritium, T). In various embodiments, "hydrogen" may be 1H (protium, H).

[0143] At various places in the present specification, substituents of compounds are disclosed in groups or in ranges. It is expressly intended that such description includes every individual subcombination of the members of these groups and ranges. For example, the term "C1-C8 alkoxy" is specifically intended to disclose individually C1, C2, C3, C4, C5, C6, C7, C8, C1-C8, C1-C7, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C8, C2-C7, C2-C6, C2-C5, C2-C4, C2-C3, C3-C8, C3-C7, C3-C6, C3-C5, C3-C4, C4-C8, C4-C7, C4-C6, C4-C5, C5-C8, C5-C7, C5-C6, C6-C8, C6-C7, and C7-C8 alkoxy.

[0144] As other examples, the integers in the range of 5-40 are specifically intended to disclose individually 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, and 40; the integers in the range of 1-20 are specifically intended to disclose individually 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, and 20. Accordingly, other groups or ranges are specifically contemplated.

[0145] When the above groups are substituted, the substituents may be independently selected from halogen atoms or heteroatoms.

[0146] A battery cell includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode sheet, a negative electrode sheet and a separator. The separator is located between the positive electrode sheet and the negative electrode sheet to isolate the positive electrode sheet from the negative electrode sheet. Lithium ions migrate between the positive electrode sheet and the negative electrode sheet through the electrolyte, thereby realizing the charging and discharging of the battery cell.

[0147] When the battery cell is a lithium metal battery, the negative electrode plate may include a negative electrode current collector, and the negative electrode plate may not include a negative electrode active material layer; of course, the negative electrode plate may also include a negative electrode active material layer, and the negative electrode active material layer may include lithium metal or lithium alloy, etc. Since lithium metal has a relatively high theoretical gram capacity, a relatively low density and a relatively negative electrode potential, using lithium metal as a negative electrode active material can significantly increase the energy density of the battery cell, which is crucial for the realization of application scenarios such as long-range electric vehicles, drones, and electric aircraft.

[0148] However, during the charge and discharge cycle of lithium metal batteries, lithium metal is deposited on the surface of the negative electrode. Side reactions are easily caused when the lithium metal surface comes into contact with the electrolyte, resulting in the consumption of lithium metal, thereby reducing the cycle life of the lithium metal battery.

[0149] In view of this, the embodiment of the present application starts from the perspective of the electrolyte. The electrolyte includes a substituted or unsubstituted first nitrogen-containing alkane. The first nitrogen-containing alkane, as an important component of the organic solvent, can effectively promote the formation of a solid electrolyte interface (SEI) film rich in nitrogen-containing compounds on the surface of the negative electrode. The SEI film can effectively passivate the surface of the negative electrode, and protect the negative electrode, reduce the side reaction between the negative electrode and the electrolyte, and because the SEI film is rich in nitrogen-containing compounds, such compounds can promote the uniform and dense deposition of lithium metal, improve the cycle reversibility of the battery cell, and increase the cycle life of the battery cell; and the first nitrogen-containing alkane has a strong oxidation resistance. Under a relatively high-voltage system, it can improve the stability of the electrolyte and further improve the cycle life of the battery cell. Next, the technical solution of the present application is described in detail.

[0150] Electrolyte

[0151] In a first aspect, an embodiment of the present application provides an electrolyte.

[0152] The electrolyte includes an organic solvent, which includes a substituted or unsubstituted first nitrogen-containing alkane, wherein the nitrogen atom in the first nitrogen-containing alkane is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, wherein when the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane includes at least one branched alkyl group; when the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane is substituted by at least a halogen atom, and the halogen atom substitution position is the carbon atom position indirectly connected to the nitrogen atom.

[0153] The substituted or unsubstituted first nitrogen-containing alkane may include at least one nitrogen atom, each nitrogen atom and a carbon atom are connected by a covalent single bond to form an amine structure, especially a secondary amine structure and a tertiary amine structure. The amine structure is an electron-rich structure with strong reduction resistance. The structure can promote the formation of an SEI film on the surface of the negative electrode. The SEI film can effectively passivate the surface of the negative electrode, and protect the negative electrode, reduce the side reaction between the negative electrode and the electrolyte, and because the SEI film is rich in nitrogen-containing compounds, such compounds can promote the uniform and dense deposition of lithium metal, improve the cycle reversibility of the battery cell, and increase the cycle life of the battery cell. Optionally, the amine structure is at least one of a secondary amine structure and a tertiary amine structure; more preferably, a tertiary amine structure can improve the stability of the amine structure to the negative electrode.

[0154] Since the electrolyte of the embodiment of the present application is mainly used in high voltage systems, for example, the working voltage is above 4V, in this system, the risk of side reactions between the electrolyte and the positive electrode active material layer in the positive electrode plate increases, and the electrolyte may decompose at the positive electrode plate. In order to improve the cycle stability of the electrolyte, the embodiment of the present application is mainly achieved by improving the oxidation resistance of the electrolyte, especially the oxidation resistance of the substituted or unsubstituted first nitrogen-containing alkane. The embodiment of the present application mainly improves the oxidation resistance by increasing at least one of steric hindrance and halogen substitution.

[0155] When the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane comprises at least one branched alkyl group. By providing a branched structure in the first nitrogen-containing alkane, the oxidation resistance of the first nitrogen-containing alkane can be improved through a steric hindrance effect. The branched alkyl group is a branch relative to the main molecular chain of the first nitrogen-containing alkane. For example, if the main molecular chain is a linear molecular chain, the side group connected to the main molecular chain is a branch; for another example, if the main molecular chain is a cyclic molecular chain, the side group connected to the cyclic molecular chain is a branch.

[0156] When the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane is at least substituted by a halogen atom, and the electron-withdrawing ability of the halogen atom is stronger. By halogen-substituting the first nitrogen-containing alkane, the oxidation resistance of the first nitrogen-containing alkane can be improved by electron-withdrawing. And the halogen atom substitution position is the carbon atom position indirectly connected to the nitrogen atom, which can make the lone pair of electrons of the nitrogen atom coordinate with the empty orbit of the lithium ion in the electrolyte, which is conducive to the dissolution of the lithium salt in the electrolyte and improves the stability of the electrolyte. If the halogen atom substitution position is the carbon atom position adjacent to the nitrogen atom, since the carbon atom at this position is replaced by a halogen atom with a strong electron-withdrawing effect, the lone pair of electrons of the nitrogen atom will lose the coordination ability with the lithium ion, resulting in the lithium salt being difficult to dissolve in the first nitrogen-containing alkane solvent. In the embodiment of the present application, the carbon atom ortho to the nitrogen atom is referred to as the carbon atom directly connected to the nitrogen atom, and the non-ortho carbon atom is referred to as the carbon atom indirectly connected to the nitrogen atom.

[0157] Therefore, according to the electrolyte of the embodiment of the present application, the electrolyte includes a substituted or unsubstituted first nitrogen-containing alkane. The first nitrogen-containing alkane, as an important component of the organic solvent, can effectively promote the formation of a SEI film rich in nitrogen-containing compounds on the surface of the negative electrode plate. The SEI film can effectively passivate the surface of the negative electrode plate, and protect the negative electrode plate, thereby reducing the side reactions between the negative electrode plate and the electrolyte. Moreover, since the SEI film is rich in nitrogen-containing compounds, such compounds can promote the uniform and dense deposition of lithium metal, improve the cycle reversibility of the battery cell, and increase the cycle life of the battery cell. Moreover, the first nitrogen-containing alkane has a strong oxidation resistance. Under a relatively high-voltage system, it can improve the stability of the electrolyte and further improve the cycle life of the battery cell.

[0158] The first nitrogen-containing alkane described in the embodiment of the present application may be unsubstituted, that is, the first nitrogen-containing alkane mainly includes carbon atoms, hydrogen atoms and nitrogen atoms. The structural formula of the first nitrogen-containing alkane is described in detail below.

[0159] In some embodiments, when the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane contains at least one branched alkyl group; as the number of branched alkyl groups increases, the steric effect of the first nitrogen-containing alkane becomes stronger, which is more conducive to improving the oxidation resistance of the first nitrogen-containing alkane. Optionally, the number of branched alkyl groups may be more than two; further optionally, the number of branched alkyl groups may be more than three.

[0160] Illustratively, when the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane may contain one branched alkyl group, two branched alkyl groups, three branched alkyl groups, four branched alkyl groups, five branched alkyl groups, six branched alkyl groups, or a combination of any two of the above numbers.

[0161] In some embodiments, the branched alkyl group may be a C1 to C5 alkyl group; optionally a C1 to C3 alkyl group. The molecular chain of the branched alkyl group is relatively short. On the basis of exerting steric hindrance, it can also enhance the solubility of lithium salts, which is beneficial to enhance the ion conductivity of the electrolyte.

[0162] The number of carbon atoms in the branched alkyl group can be from one to three, for example, one, two or three.

[0163] Optionally, the branched alkyl group is attached to the carbon atom position that is directly attached to the nitrogen atom, ie, the branched alkyl group is attached to the carbon atom ortho to the nitrogen atom.

[0164] [Unsubstituted nitrogen-containing linear alkanes]

[0165] In some embodiments, the unsubstituted first nitrogen-containing alkane includes an unsubstituted nitrogen-containing linear alkane, the unsubstituted nitrogen-containing linear alkane includes a nitrogen-containing straight-chain alkyl group and the branched alkyl group connected to the nitrogen-containing straight-chain alkyl group, the nitrogen atom in the nitrogen-containing straight-chain alkyl group is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms. The above compound can promote the formation of a SEI film rich in nitrogen-containing compounds, improve the interface structure of the negative electrode plate, and is conducive to the uniform and dense deposition of lithium metal; and the compound has a strong oxidation resistance.

[0166] The unsubstituted nitrogen-containing linear alkane includes at least one branched alkyl group. Optionally, the number of the branched alkyl groups may be two or more; further optionally, the number of the branched alkyl groups may be three or more.

[0167] The nitrogen-containing straight-chain alkyl group of the unsubstituted nitrogen-containing linear alkane includes at least one nitrogen atom; illustratively, the nitrogen-containing straight-chain alkyl group includes one, two, three or four nitrogen atoms; further optionally, the number of nitrogen atoms in the nitrogen-containing straight-chain alkyl group is 1 to 3, and the compound is conducive to the dissolution of lithium salts and the ion transport of electrolytes.

[0168] In some embodiments, the unsubstituted nitrogen-containing linear alkane includes a compound represented by formula (I),

[0169]

[0170] In formula (I),

[0171] R 1 and R 2 Each independently comprises a C1 to C8 alkyl group;

[0172] R 3 Includes a hydrogen atom or a C1 to C3 alkyl group.

[0173] Among them, when R 3 When hydrogen atoms are included, R 1and R 2 At least one of the alkyl groups includes a branched alkyl group.

[0174] When R 3 When including C1 to C3 alkyl groups, R 3 A branched alkyl group capable of forming a nitrogen-containing linear alkane, in which case R 1 and R 2 At least one of them may include a branched alkyl group to increase the steric hindrance effect; of course, R 1 and R 2 Branched alkyl groups may not be included.

[0175] The C1 to C8 alkyl group includes a branched alkyl group, which means that the C1 to C8 alkyl group includes, in addition to the main molecular chain, a side chain connected to the main molecular chain. For example, the C1 to C8 alkyl group may include isopropyl, isobutyl, isopentyl, isohexyl, isoheptyl, isooctyl, and the like.

[0176] Illustratively, the compound represented by formula (I) includes at least one of the compounds represented by formula (I-1) to the compounds represented by formula (I-3),

[0177]

[0178] In some embodiments, the unsubstituted nitrogen-containing linear alkane includes a compound represented by formula (II),

[0179]

[0180] In formula (II),

[0181] R 4 To R 6 Each independently comprises a C1 to C8 alkyl group;

[0182] R 7 and R 8 Each independently includes a hydrogen atom or a C1 to C3 alkyl group.

[0183] Among them, when R 7 and R 8 When all include hydrogen atoms, R 4 To R 6 At least one of the alkyl groups includes a branched alkyl group.

[0184] When R 7 and R 8 When at least one of the above comprises a C1 to C3 alkyl group, the C1 to C3 alkyl group can constitute a branched alkyl group of a nitrogen-containing linear alkane. In this case, R 4 To R 6 At least one of them may include a branched alkyl group to increase the steric hindrance effect; of course, R 4 To R6 Branched alkyl groups may not be included.

[0185] Optionally, R 7 and R 8 Each independently includes a C1 to C3 alkyl group.

[0186] Optionally, R 4 To R 6 The same groups are included.

[0187] Optionally, R 7 and R 8 The same groups are included.

[0188] Optionally, the number of carbon atoms between two nitrogen atoms in the compound represented by formula (II) can be one, two, three, four, etc.

[0189] Illustratively, the compound represented by formula (II) includes at least one of the compounds represented by formula (II-1) to the compounds represented by formula (II-8),

[0190]

[0191] In some embodiments, the unsubstituted nitrogen-containing linear alkane includes a compound represented by formula (III),

[0192]

[0193] In formula (III),

[0194] R 9 To R 12 Each independently comprises a C1 to C8 alkyl group;

[0195] R 13 To R 15 Each independently includes a hydrogen atom or a C1 to C3 alkyl group,

[0196] Among them, when R 13 To R 15 When all include hydrogen atoms, R 9 To R 12 At least one of the alkyl groups includes a branched alkyl group.

[0197] When R 13 To R 15 When at least one of the above comprises a C1 to C3 alkyl group, the C1 to C3 alkyl group can constitute a branched alkyl group of a nitrogen-containing linear alkane. In this case, R 9 To R 12 At least one of them may include a branched alkyl group to increase the steric hindrance effect; of course, R 9 To R 12 Branched alkyl groups may not be included.

[0198] Optionally, R 13 To R 15 Each independently includes a C1 to C3 alkyl group.

[0199] Optionally, R 9 To R 12 The same groups are included.

[0200] Optionally, R 13 To R 15 The same groups are included.

[0201] Illustratively, the compound represented by formula (III) includes at least one of the compounds represented by formula (III-1) to the compounds represented by formula (III-4),

[0202]

[0203] [Unsubstituted nitrogen-containing cyclic alkanes]

[0204] In some embodiments, the unsubstituted first nitrogen-containing alkane includes an unsubstituted nitrogen-containing cyclic alkane, the unsubstituted nitrogen-containing cyclic alkane includes a cyclic structure and at least two branched alkyl groups connected to carbon atoms in the cyclic structure, the nitrogen atom in the cyclic structure is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms. The above compound can promote the formation of a SEI film rich in nitrogen-containing compounds, improve the interface structure of the negative electrode plate, and is conducive to the uniform and dense deposition of lithium metal; and the compound has a strong oxidation resistance.

[0205] In some embodiments, the unsubstituted nitrogen-containing cyclic alkane includes a compound represented by formula (IV),

[0206]

[0207] In formula (IV),

[0208] R 16 including C1 to C8 alkyl groups;

[0209] R 17 including a hydrogen atom or a C1 to C3 alkyl group,

[0210] Among them, when R 17 When hydrogen atoms are included, R 17 including branched chain alkyl groups;

[0211] When R 17 When C1 to C3 alkyl is included, the C1 to C3 alkyl can constitute a branched alkyl of a nitrogen-containing linear alkane. In this case, R 16 Branched alkyl groups may be included to increase steric hindrance; of course, R16 Branched alkyl groups may not be included.

[0212] Illustratively, the compound represented by formula (IV) includes at least one of the compound represented by formula (IV-1) and the compound represented by formula (IV-4),

[0213]

[0214] In some embodiments, the unsubstituted nitrogen-containing cyclic alkane includes a compound represented by formula (V),

[0215]

[0216] In formula (IV),

[0217] R 18 and R 19 Each independently comprises a C1 to C8 alkyl group;

[0218] R 20 and R 21 Each independently includes a hydrogen atom or a C1 to C3 alkyl group,

[0219] Among them, when R 20 and R 21 When all include hydrogen atoms, R 18 To R 19 At least one of the following comprises a branched alkyl group;

[0220] When R 20 and R 21 When at least one of the above comprises a C1 to C3 alkyl group, the C1 to C3 alkyl group can constitute a branched alkyl group of a nitrogen-containing linear alkane. In this case, R 18 To R 19 At least one of them may include a branched alkyl group to increase the steric hindrance effect; of course, R 18 To R 19 At least one of the above may not include a branched alkyl group.

[0221] Optionally, R 20 and R 21 Each independently includes a C1 to C3 alkyl group.

[0222] Optionally, R 18 and R 19 The same groups are included.

[0223] Optionally, R 20 and R 21 The same groups are included.

[0224] Illustratively, the compound represented by formula (V) includes at least one of the compounds represented by formula (V-1) to the compounds represented by formula (V-6),

[0225]

[0226] The first nitrogen-containing alkane in the embodiment of the present application can be substituted, that is, the hydrogen atoms in the first nitrogen-containing alkane can be replaced by other groups. In addition to carbon atoms, hydrogen atoms and nitrogen atoms, the first nitrogen-containing alkane can also include other groups. The other groups may include halogen atoms. The halogen atom substitution position is the carbon atom position indirectly connected to the nitrogen atom, that is, the carbon atom position of the nitrogen atom at the meta position, para position, etc.; the halogen atom may include at least one of a fluorine atom, a chlorine atom, and a bromine atom, and can be selected from fluorine atoms. The fluorine atom has a stronger electron-withdrawing effect, which is beneficial to improving the oxidation resistance of the first nitrogen-containing alkane. The structural formula of the first nitrogen-containing alkane is described in detail below.

[0227] In some embodiments, when the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane contains at least one halogen atom such as a fluorine atom; as the number of fluorine atoms increases, the electron-withdrawing effect of the first nitrogen-containing alkane becomes stronger, which can further enhance the antioxidant capacity of the first nitrogen-containing alkane; optionally, the first nitrogen-containing alkane includes 1 to 3 fluorine atoms; optionally 1 to 2 fluorine atoms.

[0228] In some embodiments, when the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane may further include a branched alkyl group, and the branched alkyl group improves the steric effect of the first nitrogen-containing alkane, thereby further improving the oxidation resistance of the first nitrogen-containing alkane. Exemplarily, when the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane may include one branched alkyl group, two branched alkyl groups, three branched alkyl groups, four branched alkyl groups, five branched alkyl groups, six branched alkyl groups, or a combination of any two of the above numbers.

[0229] The number of carbon atoms in the branched alkyl group can be from one to three, for example, one, two or three.

[0230] Optionally, the branched alkyl group is attached to the carbon atom position that is directly attached to the nitrogen atom, ie, the branched alkyl group is attached to the carbon atom ortho to the nitrogen atom.

[0231] [Substituted nitrogen-containing linear alkanes]

[0232] In some embodiments, the substituted first nitrogen-containing alkane includes a substituted nitrogen-containing linear alkane, and the substituted nitrogen-containing linear alkane includes at least one halogen atom; optionally, one to four halogen atoms; the halogen atom may be a fluorine atom. The above compound has a strong solubility in lithium salts, which is conducive to the dissolution of lithium salts to form a stable electrolyte; it can also promote the formation of a SEI film rich in nitrogen-containing compounds, improve the interface structure of the negative electrode plate, and is conducive to the uniform and dense deposition of lithium metal; and the compound has a strong oxidation resistance.

[0233] In some embodiments, the substituted nitrogen-containing linear alkane includes a compound represented by formula (A),

[0234]

[0235] In formula (A),

[0236] Q 1 and Q 2 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0237] Q 3 including a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0238] And Q 1 To Q 3 At least one of them is substituted by a halogen atom.

[0239] Illustratively, the compound represented by formula (A) includes at least one of the compounds represented by formula (A-1) to the compounds represented by formula (A-3),

[0240]

[0241] In some embodiments, the substituted nitrogen-containing linear alkane includes a compound represented by formula (B),

[0242]

[0243] In formula (B),

[0244] Q 4 To Q 6 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0245] Q 7 and Q 8 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0246] And Q 4 To Q 8 At least one of them is substituted by a halogen atom.

[0247] Optionally, Q 7 and Q 8 The same groups are included.

[0248] Optionally, Q 4 To Q 6 The same groups are included.

[0249] Illustratively, the compound represented by formula (B) includes at least one of the compounds represented by formula (B-1) to the compounds represented by formula (B-4),

[0250]

[0251] In some embodiments, the substituted nitrogen-containing linear alkane includes a compound represented by formula (C),

[0252]

[0253] In formula (C),

[0254] Q 9 To Q 12 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0255] Q 13 To Q 15 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0256] And Q 9 To Q 15 At least one of them is substituted by a halogen atom.

[0257] Optionally, Q 9 To Q 12 The same groups are included.

[0258] Optionally, Q 13 To Q 15 The same groups are included.

[0259] Illustratively, the compound represented by formula (C) includes at least one of the compounds represented by formula (C-1) to the compounds represented by formula (C-3),

[0260]

[0261] [Substituted nitrogen-containing cyclic alkanes]

[0262] In some embodiments, the substituted first nitrogen-containing alkane includes a substituted nitrogen-containing cyclic alkane, wherein the substituted nitrogen-containing cyclic alkane includes a cyclic structure, wherein a nitrogen atom in the cyclic structure is connected to a carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms.

[0263] The nitrogen-containing cyclic alkane is substituted by a halogen atom, and the halogen atom substitution position is a carbon atom position indirectly connected to the nitrogen atom.

[0264] In some embodiments, the substituted nitrogen-containing cyclic alkane includes a compound represented by formula (D),

[0265]

[0266] In formula (D),

[0267] Q 16 including substituted or unsubstituted C1 to C8 alkyl groups;

[0268] Q 17 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0269] And, Q 16 and Q 17 At least one of them is substituted by a halogen atom;

[0270] Optionally, there may be one to two halogen atoms; optionally, the halogen atoms include fluorine atoms.

[0271] Alternatively, the substitution position of the fluorine atom may be a carbon atom position meta to the nitrogen atom.

[0272] Illustratively, the compound represented by formula (D) includes at least one of the compound represented by formula (D-1) and the compound represented by formula (D-2),

[0273]

[0274] In some embodiments, the substituted nitrogen-containing cyclic alkane includes a compound represented by formula (E),

[0275]

[0276] In formula (E),

[0277] Q 18 and Q 19 including substituted or unsubstituted C1 to C8 alkyl groups;

[0278] Q 20 and Q 21 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0279] And, Q 18 To Q 21 At least one of them is substituted by a halogen atom; the halogen atom is, for example, a fluorine atom.

[0280] Illustratively, the compound represented by formula (E) includes at least one of the compound represented by formula (E-1) and the compound represented by formula (E-2), which can be the compound represented by formula (E-1),

[0281]

[0282] In an embodiment of the present application, the above-mentioned first nitrogen-containing alkane compound can balance the size of the nitrogen-carbon structure, the spacing between each nitrogen atom, the degree of branching, and the position and amount of fluorine substitution. This structure, as the main solvent of the electrolyte, can obtain good lithium ion conductivity, excellent redox resistance window, dense lithium metal deposition, and long cycle life of lithium metal batteries.

[0283] In some embodiments, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the substituted or unsubstituted first nitrogen-containing alkane is greater than or equal to 20% and less than 100%, optionally 40% to 80%, and further optionally 50% to 65%. The use of the first nitrogen-containing alkane having the above mass percentage can improve the ion conductivity of the electrolyte and improve the stability of the electrolyte for the positive and negative electrodes.

[0284] It should be noted that the total mass of the organic solvent in the electrolyte may include the total mass of the first nitrogen-containing alkane compound, the second nitrogen-containing alkane compound, the fluorinated solvent, the ester solvent, the ether solvent, and the like.

[0285] For example, the mass percentage of the first nitrogen-containing alkane can be 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, 100%, 101%, 102%, 103%, 104%, 105%, 106%, 107%, 108%, 109%, 110%, 111%, 112%, 113%, 114%, 115%, 116%, 117%, 118%, 119%, 120%, 121%, 122%, 123 53%, 54%, 55%, 56%, 57%, 58%, 60%, 62%, 63%, 64%, 65%, 66%, 68%, 70%, 72%, 74%, 75%, 76%, 77%, 78%, 80%, 81%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 93%, 94%, 95%, 96%, 98%, 99% or a range consisting of any two of the above values.

[0286] [Second nitrogen-containing alkane]

[0287] In some embodiments, the electrolyte may further include a second nitrogen-containing alkane, wherein the nitrogen atom in the second nitrogen-containing alkane is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, wherein at least one of the carbon atoms adjacent to the nitrogen atom is substituted by a halogen atom.

[0288] On the one hand, since the second nitrogen-containing alkane contains halogen atoms, it can improve the overall oxidation resistance of the electrolyte, which helps to improve the stability of the electrolyte to the positive electrode sheet with an operating voltage of more than 4V. On the other hand, halogen atoms such as fluorine atoms can decompose to generate fluorine-rich SEI film components during the lithium metal deposition process, further improving lithium metal deposition and cycle reversibility. Therefore, the second nitrogen-containing alkane and the first nitrogen-containing alkane can play a synergistic role in further improving the reversibility of positive and negative electrode cycles; and the second nitrogen-containing alkane can be well miscible with the first nitrogen-containing alkane, further improving the stability of the electrolyte.

[0289] In some embodiments, the number of halogen atoms is at least one, and can be selected from one to six, such as one, two, three, four, five, six, and the like.

[0290] In some embodiments, the halogen atom may be at least one of a fluorine atom, a chlorine atom, and a bromine atom, and may be a fluorine atom. The fluorine atom has a strong electron-withdrawing effect, which can further enhance the oxidation resistance of the second nitrogen-containing alkane.

[0291] In some embodiments, the second nitrogen-containing alkane may include a nitrogen-containing linear alkane.

[0292] In some embodiments, the second nitrogen-containing alkane comprises a compound represented by formula (1),

[0293]

[0294] In formula (1),

[0295] M 1 and M 2 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0296] M 3 including a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0297] And M 1 To M 3 At least one of them is substituted by a halogen atom, and the halogen atom is attached to the carbon atom adjacent to the nitrogen atom.

[0298] Illustratively, the compound represented by formula (1) includes at least one of the compounds represented by formula (1-1) to the compounds represented by formula (1-3),

[0299]

[0300] In some embodiments, the second nitrogen-containing alkane comprises a compound represented by formula (2),

[0301]

[0302] In formula (2),

[0303] M 4 To M 6 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0304] M 7 and M 8 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0305] And M 4 To M 8 At least one of them is substituted by a halogen atom, and the halogen atom is attached to the carbon atom adjacent to the nitrogen atom.

[0306] Illustratively, the compound represented by formula (2) includes at least one of the compounds represented by formula (2-1) to the compounds represented by formula (2-4),

[0307]

[0308] In some embodiments, the second nitrogen-containing alkane comprises a compound represented by formula (3),

[0309]

[0310] In formula (3),

[0311] M 9 To M 12 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group;

[0312] M 13 To M 15 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group;

[0313] And M 9 To M 15 At least one of the above is substituted by a halogen atom, the halogen atom being attached to a carbon atom adjacent to the nitrogen atom. Optionally, the halogen atom comprises a fluorine atom.

[0314] Illustratively, the compound represented by formula (3) includes at least one of the compound represented by formula (3-1) and the compound represented by formula (3-2),

[0315]

[0316] In some embodiments, the second nitrogen-containing alkane may include a nitrogen-containing cyclic alkane, which includes a ring structure, in which the nitrogen atom is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, and the nitrogen-containing cyclic alkane is substituted with a halogen atom, and the halogen atom substitution position is the carbon atom position adjacent to the nitrogen atom.

[0317] In some embodiments, the second nitrogen-containing alkane comprises a compound represented by formula (4),

[0318]

[0319] In formula (4),

[0320] M 16 including substituted or unsubstituted C1 to C8 alkyl groups;

[0321] M 17 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0322] And M 16 and M 17 At least one of them is substituted by a halogen atom, and the halogen atom is attached to the carbon atom adjacent to the nitrogen atom.

[0323] Optionally, the halogen atom includes a fluorine atom. The substitution position of the fluorine atom may be a carbon atom position adjacent to the nitrogen atom.

[0324] Illustratively, the compound represented by formula (4) includes at least one of the compound represented by formula (4-1) and the compound represented by formula (4-2),

[0325]

[0326] In some embodiments, the second nitrogen-containing alkane comprises a compound represented by formula (5),

[0327]

[0328] In formula (5),

[0329] M 18 and M 19 including substituted or unsubstituted C1 to C8 alkyl groups;

[0330] M 20 and M 21 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups,

[0331] And M 18 To M 21 At least one of them is substituted by a halogen atom, and the halogen atom is attached to the carbon atom adjacent to the nitrogen atom.

[0332] Illustratively, the compound represented by formula (5) includes at least one of the compounds represented by formula (5-1) to the compounds represented by formula (5-4),

[0333]

[0334] In some embodiments, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the second nitrogen-containing alkane is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%. When the mass percentage of the second nitrogen-containing alkane is within the above range, the oxidation resistance and film-forming effect of the electrolyte can be improved, and the adverse effect on the dissolution of the lithium salt can be reduced.

[0335] Illustratively, the mass percentage of the second nitrogen-containing alkane can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or a range consisting of any two of the above values.

[0336] [Fluorinated solvents]

[0337] In some embodiments, the electrolyte may further include a fluorinated solvent, the fluorinated solvent including at least one of a fluorinated ether solvent, a fluorinated aromatic solvent, and a fluorinated saturated alkane solvent, wherein the fluorine atom substitution position in the fluorinated ether solvent is a carbon atom position adjacent to an oxygen atom.

[0338] On the one hand, since fluorinated solvents contain halogen atoms such as fluorine atoms, they can enhance the overall oxidation resistance of the electrolyte and help improve the stability of the electrolyte to the positive electrode with an operating voltage of more than 4V. On the other hand, halogen atoms such as fluorine atoms can decompose during the lithium metal deposition process to generate fluorine-rich SEI film components, further improving lithium metal deposition and cycle reversibility.

[0339] In some embodiments, the fluorinated ether solvents include, but are not limited to, 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane, bis(2,2,2-trifluoroethyl)ether, 1,1,2,3,3,3-hexafluoropropyl ethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, ethyl trifluoromethyl ether, difluoro At least one of methyl-2,2,3,3,3-pentafluoropropyl ether, heptafluoropropyl-1,2,2,2-tetrafluoroethyl ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, perfluoroisopropyl methyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, ethyl-1,1,2,2-tetrafluoroethyl ether, ethyl-2,2,2-tetrafluoroethyl ether and bis(1,1,2,2-tetrafluoroethyl) ether.

[0340] Optionally, the fluoroether solvent includes at least one of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether and 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane.

[0341] In some embodiments, the fluorinated aromatic solvent includes, but is not limited to, at least one of fluorobenzene, p-difluorobenzene, m-difluorobenzene, o-difluorobenzene, trifluorotoluene, and trifluoromethoxybenzene.

[0342] In some embodiments, the fluorinated saturated alkane solvent includes, but is not limited to, at least one of decafluoropentane and fluorinated hexane.

[0343] In some embodiments, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the fluorinated solvent is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%. When the mass percentage of the fluorinated solvent is within the above range, the oxidation resistance and film-forming effect of the electrolyte can be improved, and the adverse effect on the dissolution of the lithium salt can be reduced.

[0344] Illustratively, the mass percentage of the fluorinated solvent can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or a range consisting of any two of the above values.

[0345] [Cosolvent]

[0346] In some embodiments, the electrolyte may further include a co-solvent, which includes at least one of an ester solvent and an ether solvent. The electrolyte uses a substituted or unsubstituted first nitrogen-containing alkane as a main solvent, and is combined with an ester solvent and an ether solvent, which is conducive to dissolving the lithium salt in the solvent and improving the ion conductivity of the electrolyte.

[0347] Moreover, the ester solvent, the ether solvent, the second nitrogen-containing alkane, and the fluorinated solvent are all well miscible with each other, which is beneficial to improving the stability of the electrolyte.

[0348] In some embodiments, the ester solvent may include, but is not limited to, at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, methyl trifluoroethyl carbonate, ethyl trifluoroethyl carbonate, di(2,2,2-trifluoroethyl) carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl 2,2,2-trifluoroacetate, and ethyl 2,2,2-trifluoroacetate.

[0349] In some embodiments, the ether solvent may include but is not limited to at least one of methyl ether, ethyl ether, propyl ether, butyl ether, methyl ethyl ether, methyl propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, propyl butyl ether, dimethoxymethane, diethoxymethane, dipropoxymethane, dimethoxyethane, dimethoxypropane, diethoxyethane, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane.

[0350] Optionally, the ether solvent may include at least one of dimethoxymethane and methyl ethyl ether. The above ether solvents have strong solubility for lithium salts, which can further improve the ion conductivity of the electrolyte, and this type of solvent has good stability for the positive electrode plates and the negative electrode plates.

[0351] In some embodiments, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the co-solvent is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%.

[0352] Illustratively, the mass percentage of the co-solvent can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40% or a range consisting of any two of the above values.

[0353] [additive]

[0354] In some embodiments, the electrolyte may further include an additive, and the additive may include at least one of propane sultone, vinyl sulfate, vinyl sulfite, tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilane) borate, dimethyl maleic anhydride, and 1,4-diisocyanate. The additive mainly assists SEI film formation, and can further help improve the stability of the positive and negative electrodes of the lithium metal battery and increase the cycle life.

[0355] In some embodiments, based on the total mass of the electrolyte, the mass percentage of the additive is 0% to 5%; optionally 0.5% to 3%.

[0356] For example, the mass percentage of the additive may be 0%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or a range consisting of any two of the above values.

[0357] [Lithium salt]

[0358] In some embodiments, the electrolyte may further include a lithium salt, which may include lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF 6 ), lithium tetrafluoroborate (LiBF 4 ) lithium hexafluoroarsenate (LiAsF 6 ), lithium bis(trifluoromethanesulfonyl imide) (LiTFSI), lithium trifluoromethanesulfonate (LiOTF), lithium difluorophosphate (LiDFP), lithium dioxalate borate (LiBOB), lithium difluorooxalate borate (LiDFOB), lithium difluorobis(oxalate phosphate) and lithium tetrafluorooxalate phosphate, which can be lithium bis(fluorosulfonyl imide). The above lithium salts can be decomposed on the surface of the negative electrode to form an inorganic fluorine-rich SEI film component, which is beneficial to the long cycle of lithium metal batteries, and has relatively good oxidation stability, which can improve the cycle life under high voltage working voltage.

[0359] In some embodiments, the molar concentration of the lithium salt is 0.5 mol / L to 4 mol / L. It can be 0.8 mol / L to 2.4 mol / L, and further can be 1.2 mol / L to 1.8 mol / L. The use of lithium salt concentrations within the above ranges can improve the ion transport performance of the electrolyte and improve the stability of the electrolyte to the positive and negative electrodes.

[0360] Illustratively, the molar concentration of the lithium salt can be 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, 1.5 mol / L, 1.6 mol / L, 1.7 mol / L, 1.8 mol / L, 1.9 mol / L, 2.0 mol / L, 2.1 mol / L, 2.2 mol / L, 2.3mol / L, 2.4mol / L, 2.5mol / L, 2.6mol / L, 2.7mol / L, 2.8mol / L, 2.9mol / L, 3.0mol / L, 3.1mol / L, 3.2mol / L, 3.3mol / L, 3.4mol / L, 3.5mol / L, 3.6mol / L, 3.7mol / L, 3.8mol / L, 3.9mol / L, 4.0mol / L or a range consisting of any two of the above values.

[0361] In the embodiments of the present application, the specific structural formula and content of each component in the electrolyte are measured in a fresh electrolyte. A fresh electrolyte refers to an electrolyte prepared from various components, which has not yet been assembled into a battery cell. It can also be an electrolyte in a battery cell that has been circulated for less than 20 times, and the battery cell is disassembled and the electrolyte is taken out for testing.

[0362] The specific structural formula of each component in the electrolyte can be confirmed by combining gas / liquid chromatography-high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy. Among them, gas / liquid chromatography can separate all components, pass high-resolution mass spectrometry to determine the molecular weight and atomic composition of each component, and then confirm the specific structure of each component through nuclear magnetic resonance spectroscopy.

[0363] The molar mass of lithium salt in the electrolyte can be detected and calculated by ion chromatography. Ion chromatography can directly confirm the mass percentage of lithium salt in the entire electrolyte, thereby obtaining its molar mass;

[0364] The mass percentage of each solvent component in the total organic solvent in the electrolyte can be detected and confirmed by gas chromatography. The mass percentage of the solvent component in the total solvent can be confirmed by the normalized area method.

[0365] Battery Cell

[0366] In a second aspect, an embodiment of the present application provides a battery cell, wherein the battery cell includes an electrolyte as in any embodiment of the first aspect of the present application.

[0367] [Negative electrode]

[0368] In some embodiments, the battery cell further includes a negative electrode tab.

[0369] In some embodiments, the battery cell is a lithium metal battery or a negative electrode-free lithium metal battery.

[0370] During the manufacturing process of lithium metal batteries, the negative electrode active material layer may not be actively set on the negative electrode side. For example, during the manufacturing process of the battery, a lithium metal or carbonaceous active material layer is not set at the negative electrode through coating or deposition to form a negative electrode active material layer. During the first charge, lithium ions obtain electrons on the negative electrode side and metallic lithium is deposited on the surface of the negative electrode current collector to form a lithium metal phase. During discharge, metallic lithium can be converted into lithium ions and return to the positive electrode to achieve cyclic charge and discharge. Compared with other lithium secondary batteries, negative electrode-free lithium ion batteries can achieve higher energy density because they do not have a negative electrode active material layer.

[0371] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer disposed on at least one surface of the negative electrode current collector and including a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0372] In some embodiments, in order to improve battery performance, the negative electrode active material in the negative electrode active material layer may include lithium metal or a lithium-containing alloy. The lithium-containing alloy may include an alloy composed of lithium and a metal element, or an alloy composed of lithium and a semi-metal element. For example, the metal element includes at least one of tin (Sn), zinc (Zn), aluminum (Al), magnesium (Mg), silver (Ag), gold (Au), gallium (Ga), indium (In), and foil (Pt). The semi-metal element includes at least one of boron (B), carbon (C), and silicon (Si). Optionally, the negative electrode active material layer is a lithium metal foil layer, which becomes a lithium metal battery. Such a lithium metal foil layer can provide an excess lithium source for the lithium metal battery during the cycle process, effectively extending the cycle life of the lithium metal battery. .

[0373] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, a nickel foil or a copper foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one side of the polymer material base layer. As an example, the metal material may include at least one of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0374] [Positive electrode]

[0375] In some embodiments, the battery cell further includes a positive electrode tab.

[0376] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material. For example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0377] The positive electrode film layer includes a positive electrode active material, and the positive electrode active material can be a positive electrode active material for a battery cell known in the art. As an example, the positive electrode active material may include at least one of the following materials: a layered structure positive electrode active material (such as ternary, lithium nickelate / sodium, lithium cobaltate / sodium, lithium manganate / sodium, lithium / sodium-rich layered and rock salt phase layered materials), an olivine-type phosphate active material, a spinel structured positive electrode active material (such as spinel lithium manganate, spinel nickel lithium manganate, lithium-rich spinel lithium manganate, and lithium nickel lithium manganate, etc.).

[0378] For example, the general formula of the layered structure positive electrode active material is: Li x A y Ni a Co b Mn c M (1-a-b-c) Y z, wherein 0≤x≤2.1, 0≤y≤2.1, and 0.9≤x+y≤2.1; 0≤a≤1, 0≤b≤1, 0≤c≤1, and 0.1≤a+b+c≤1; 1.8≤z≤3.5; A is selected from one or more of Na, K, and Mg; M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; Y is selected from one or more of O and F. Optionally, y=0. Specifically, the layered positive electrode active material may include lithium cobalt oxide LCO, lithium nickel oxide LNO, lithium manganese oxide LMO, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 (NCM333), LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) and LiNi 0.5 Co 0.2 Mn 0.3 O 2 (NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O 2 (NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM 622 )LiNi 0.96 Co 0.02 Mn 0.02 O 2 (Ni 96 ), lithium nickel cobalt aluminum oxide (LiNi 0.85 Co 0.15 Al 0.05 O 2 )

[0379] Exemplarily, the general formula of the olivine-type phosphate active material is: Li x A y Me a M b P 1-c X c Y z, wherein 0≤x≤1.3, 0≤y≤1.3, and 0.9≤x+y≤1.3; 0.9≤a≤1.5, 0≤b≤0.5, and 0.9≤a+b≤1.5; 0≤c≤0.5; 3≤z≤5; A is selected from one or more of Na, K, and Mg; Me is selected from one or more of Mn, Fe, Co, and Ni; M is selected from one or more of B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; X is selected from one or more of S, Si, Cl, B, C, and N; and Y is selected from one or more of O and F. Specifically, the olivine-type phosphate active materials include LiFePO 4 、LiMnPO 4 、LiNiPO 4 , and LiCoPO 4 One or more of .

[0380] For example, the general formula of the positive electrode active material of the spinel structure is: Li x A y Mn a M 2-a Y z , wherein 0≤x≤2, 0≤y≤1, and 0.9≤x+y≤2; 0.5≤a≤2; 3≤z≤5; A is selected from one or more of Na, K, and Mg; M is selected from one or more of Ni, Co, B, Mg, Al, Si, P, S, Ca, Sc, Ti, V, Cr, Fe, Cu, Zn, Sr, Y, Zr, Nb, Mo, Cd, Sn, Sb, Te, Ba, Ta, W, Yb, La, and Ce; and Y is selected from one or more of O and F. Specifically, the positive electrode active materials of the spinel structure include LiMn 2 O 4 、LiNi 0.5 Mn 1.5 O 4 、LiCr 0.3 Mn 1.7 O 4 , Li 1.1 Al 0.1 Mn 1.9 O 4 , Li 2 Mn 2 O 4 and Li 1.5 Mn 2 O 4 One or more of .

[0381] In the embodiment of the present application, each of the above-mentioned positive electrode active materials may further include a modified compound of the above-mentioned compound, and the modified compound may be a doping modification and / or surface coating modification of the positive electrode active material.

[0382] The battery cell will be accompanied by the deintercalation and consumption of active ions such as Li during the charge and discharge process, and the molar content of Li in the battery cell is different when it is discharged to different states. In the list of positive electrode active materials in the embodiments of the present application, the molar content of Li is the initial state of the material, that is, the state before feeding. The positive electrode active material is used in the battery system, and the molar content of Li may change after charge and discharge cycles.

[0383] In the list of positive electrode active materials in the embodiments of the present application, the molar content of oxygen O is only a theoretical value. The release of oxygen from the lattice will cause the molar content of oxygen O to change. In reality, the molar content of oxygen O will fluctuate.

[0384] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent. The embodiment of the present application has no particular restrictions on the type of the positive electrode conductive agent. As an example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene and carbon nanofibers. In some embodiments, based on the total mass of the positive electrode film layer, the mass percentage of the positive electrode conductive agent is ≤5%.

[0385] In some embodiments, the positive electrode film layer may also optionally include a positive electrode binder. The embodiment of the present application has no particular restrictions on the type of the positive electrode binder. As an example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer and fluorine-containing acrylic resin. In some embodiments, based on the total mass of the positive electrode film layer, the mass percentage of the positive electrode binder is ≤5%.

[0386] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, aluminum foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material of the metal material layer may include at least one of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. As an example, the polymer material base layer may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS) and polyethylene (PE).

[0387] The positive electrode film layer is usually formed by coating the positive electrode slurry on the positive electrode current collector, drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder and any other components in a solvent and stirring them uniformly. The solvent can be N-methylpyrrolidone (NMP), but is not limited thereto.

[0388] [Isolation film]

[0389] In some embodiments, the battery cell further includes a separator.

[0390] The embodiments of the present application have no particular restrictions on the type of isolation membrane, and any known porous isolation membrane with good chemical stability and mechanical stability can be selected.

[0391] In some embodiments, the material of the isolation membrane may include at least one of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0392] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet may be formed into an electrode assembly by a winding process and / or a lamination process.

[0393] In some embodiments, the battery cell may include an outer packaging, which may be used to encapsulate the electrode assembly and the electrolyte.

[0394] In some embodiments, the outer packaging of the battery cell may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT) and polybutylene succinate (PBS).

[0395] The present application embodiment has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 1 The battery cell 5 is a square structure as an example.

[0396] In some embodiments, Figure 2As shown, the outer package may include a shell 51 and a cover plate 53. The shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 is used to cover the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation film can form an electrode assembly 52 through a winding process and / or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, which can be adjusted according to demand.

[0397] The preparation method of the battery cell of the embodiment of the present application is well known. In some embodiments, the positive electrode sheet, the separator, the negative electrode sheet and the electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, the separator and the negative electrode sheet can be formed into an electrode assembly through a winding process and / or a lamination process, and the electrode assembly is placed in an outer package, and the electrolyte is injected after drying, and the battery cell is obtained through vacuum packaging, standing, forming, shaping and other processes.

[0398] In some embodiments of the embodiments of the present application, the battery cells according to the embodiments of the present application can be assembled into a battery module. The number of battery cells contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.

[0399] Figure 3 FIG. 4 is a schematic diagram of a battery module 4 as an example. Figure 3 As shown, in the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0400] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0401] In some embodiments, the battery modules described above may also be assembled into a battery pack, and the number of battery modules contained in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0402] Figure 4 and Figure 5 FIG. 1 is a schematic diagram of a battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3, wherein the upper box body 2 is used to cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0403] Electrical devices

[0404] The third aspect of the embodiments of the present application provides an electric device, which includes at least one of the battery cells, battery modules or battery packs of the embodiments of the present application. The battery cells, battery modules or battery packs can be used as the power source of the electric device, and can also be used as the energy storage unit of the electric device. The electric device can be, but is not limited to, a mobile device (such as a mobile phone, a laptop computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc.

[0405] The electrical device may select a battery cell, a battery module or a battery pack according to its usage requirements.

[0406] Figure 6 Schematic diagram of an exemplary electric device 6. The electric device 6 is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the requirements of the electric device 6 for high power and high energy density, a battery pack or a battery module may be used.

[0407] As another example, the electric device may be a mobile phone, a tablet computer, a notebook computer, etc. The electric device is usually required to be light and thin, and a battery cell may be used as a power source.

[0408] Example

[0409] The following examples more specifically describe the contents disclosed in the embodiments of the present application, and these examples are only for illustrative purposes, because it is obvious to those skilled in the art that various modifications and changes are made within the scope of the disclosure of the embodiments of the present application. Unless otherwise stated, all parts, percentages and ratios reported in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0410] Examples and Comparative Examples

[0411] 1. Preparation of positive electrode sheet

[0412] Aluminum foil with a thickness of 12 μm was used as the positive electrode current collector.

[0413] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM 811), conductive agent acetylene black, and binder polyvinylidene fluoride (PVDF) are fully stirred and mixed in an appropriate amount of solvent N-methylpyrrolidone NMP at a weight ratio of 98:1:1 to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on both sides of the surface of the positive electrode collector aluminum foil, and after drying and cold pressing, a positive electrode sheet is obtained.

[0414] 2. Preparation of negative electrode sheet

[0415] A copper foil with a thickness of 12 μm was used as the negative electrode current collector.

[0416] A 50 μm lithium foil was placed on the copper foil by roller pressing to obtain a negative electrode sheet.

[0417] 3. Isolation film

[0418] A porous polyethylene (PE) film was used as the isolation membrane.

[0419] 4. Preparation of electrolyte

[0420] In an environment where the water content is less than 10 ppm, organic solvents are mixed to obtain an electrolyte solvent, and then lithium salt lithium bis(fluorosulfonyl)imide and the mixed solvent are mixed to prepare an electrolyte with a lithium salt concentration of 1.5 mol / L. The specific components in the electrolyte are shown in Table 1.

[0421] 5. Preparation of battery cells

[0422] The positive electrode sheet, the isolation film, and the negative electrode sheet are stacked in order, so that the isolation film is placed between the positive electrode sheet and the negative electrode sheet to play an isolating role, and then the sheets are stacked to obtain an electrode assembly; the electrode assembly is placed in an outer packaging shell, and after drying, the electrolyte is injected, and after vacuum packaging, standing, forming, shaping and other processes, a lithium metal battery is obtained.

[0423] Test part:

[0424] 1. Electrolyte oxidation stability test

[0425] 1. Li-Al half-cell LSV test of electrolyte oxidation stability

[0426] The 50 μm lithium foil was placed on the 12 μm copper foil by roller pressing to obtain the negative electrode; the aluminum foil was the positive electrode and cut into 1 cm 2 A small disc is used, and a polyethylene porous membrane is used as an isolation membrane. 20 μL of the electrolyte prepared in each embodiment and comparative example is injected to form a button battery.

[0427] Using a Solartron electrochemical workstation, a scanning voltammetry (LSV) test was performed at a scan rate of 5 mV / s in the voltage range from open circuit voltage to 6 V to record the current response of the battery. 2When , the corresponding voltage is taken as the critical voltage value of the oxidation stability of the electrolyte. The larger the value is, the better the stability of the electrolyte to the high-voltage positive electrode.

[0428] 2. Li-Cu half-cell LSV test of electrolyte reduction stability

[0429] A 50μm lithium foil is placed on a 12μm copper foil by rolling to obtain a negative electrode; the copper foil is used as the positive electrode and cut into 1cm2 small discs, a polyethylene porous membrane is used as an isolation membrane, and 20μL of the electrolyte prepared in each embodiment and comparative example is injected to form a button battery. Using a Solartron electrochemical workstation, a scanning voltammetry (LSV) test is performed at a scan rate of -5mV / s in the voltage range from open circuit voltage (about 3V) to 0V, and the current response of the battery is recorded. When the current density reaches -10μA / cm 2 When , the corresponding voltage is taken as the critical voltage of the reaction between the electrolyte and the lithium metal negative electrode. The smaller the value, the better the stability of the electrolyte to the lithium metal negative electrode.

[0430] 2. Long cycle test of lithium metal batteries

[0431] Take the lithium metal batteries made in the above embodiments and comparative examples, set the ambient temperature to 25°C, and use a charge and discharge rate of 0.2C (i.e. 28mA) for charging and 1C (i.e. 140mA) for charging and discharging cycles. The cut-off voltages for charging and discharging are set to 4.3V and 2.8V, respectively, and the charging process adopts a constant current-constant voltage charging method. Specifically, when the 0.2C constant current charging reaches a cut-off voltage of 4.3V, continue to use a 4.3V constant voltage charging until the current decays to 0.1C (i.e. 14mAh). When the discharge capacity decays to 80% of the first cycle discharge capacity, the battery life is considered to be over, and the number of cycles is recorded.

[0432] Test Results

[0433] The test results are shown in Table 1.

[0434] Table 1

[0435]

[0436]

[0437] In Table 1,

[0438] Solvent A represents a first nitrogen-containing alkane;

[0439] Solvent B represents a cosolvent;

[0440] Solvent C represents a second nitrogen-containing alkane and a fluorinated solvent;

[0441] Additive D represents an additive.

[0442] a% represents the mass percentage of the first nitrogen-containing alkane relative to the total mass of the organic solvent in the electrolyte; b% represents the mass percentage of the co-solvent relative to the total mass of the organic solvent in the electrolyte;

[0443] c% represents the mass percentage of the second nitrogen-containing alkane relative to the total mass of the organic solvent in the electrolyte; d% represents the mass percentage of the additive relative to the total mass of the electrolyte.

[0444] As can be seen from Table 1, by comparing Example 1 with Comparative Examples 1-4, it can be found that although the ether solvent in Comparative Example 2 has resistance to reduction, it cannot support long cycles due to its poor oxidation resistance; although the ether solvent in Comparative Example 3 has resistance to oxidation, it cannot support long cycles due to its poor resistance to reduction, which shows that for batteries matching lithium metal negative electrodes with high-voltage positive electrodes above 4V, the electrolyte has both high resistance to reduction and high resistance to oxidation. Comparative Example 2 improves the oxidation resistance of the electrolyte to a certain extent by adding solvent C, but it is still insufficient. Further addition of diethylamine containing hydrogen atoms on nitrogen atoms, because it is not branched, its acidity will cause instability to the lithium metal negative electrode, and the resistance to reduction is reduced. Compared with Comparative Example 1, the life span is not improved but reduced.

[0445] In Example 1 of the present application, by adding the first nitrogen-containing alkane, the oxidation resistance is greatly improved, and the reduction resistance window is also widened compared with Comparative Example 1, thereby achieving a breakthrough life improvement.

[0446] By comparing Examples 1-5, it can be found that, based on the total mass of the solvent, the optimal mass ratio of solvents A, B, and C is 6:2:2, at which the key effects of each component can be maximized.

[0447] By comparing Example 1 with Examples 6-11, it can be found that the optimal concentration of lithium salt is 1.5 mol / L. When the lithium salt concentration is within the above range, the oxidation resistance of the electrolyte can be improved, and the electrolyte concentration is relatively low, which can increase the decrease in ion conductivity.

[0448] By comparing Example 1 with Examples 12-26, it can be found that the nitrogen ether or fluorinated nitrogen ether solvent A can be selected from I-1, II-1, I-15 and I-16. This structure can further improve the stability of the positive and negative electrodes and the solubility of lithium salts.

[0449] By comparing Example 1 with Examples 27-32, it can be found that the solvent B can be selected from methyl butyl ether or ethylene glycol methyl ethyl ether.

[0450] By comparing Example 1 with Examples 33-39, it can be found that the solvent C can be selected as 1-1 or 1-2.

[0451] By comparing Example 1 with Examples 40 and 41, it can be found that the lithium salt can be lithium bis(fluorosulfonyl)imide.

[0452] By comparing Example 1 with Examples 42-44, it can be found that the optimal addition amount of additive D is 1%, and it has a certain improvement on the performance.

[0453] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. An electrolyte comprising an organic solvent, wherein the organic solvent comprises a substituted or unsubstituted first nitrogen-containing alkane, wherein a nitrogen atom in the first nitrogen-containing alkane is connected to a carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, in, When the first nitrogen-containing alkane is unsubstituted, the first nitrogen-containing alkane comprises at least one branched alkyl group; When the first nitrogen-containing alkane is substituted, the first nitrogen-containing alkane is at least substituted by a halogen atom, and the halogen atom substitution position is a carbon atom position indirectly connected to the nitrogen atom.

2. The electrolyte according to claim 1, wherein The unsubstituted first nitrogen-containing alkane includes an unsubstituted nitrogen-containing linear alkane, wherein the unsubstituted nitrogen-containing linear alkane includes a nitrogen-containing straight-chain alkyl group and the branched alkyl group connected to the nitrogen-containing straight-chain alkyl group, the nitrogen atom in the nitrogen-containing straight-chain alkyl group is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms.

3. The electrolyte according to claim 2, wherein The unsubstituted nitrogen-containing linear alkane comprises at least one of the compounds represented by formula (I) to the compounds represented by formula (III), In formula (I), R1 and R2 each independently include a C1 to C8 alkyl group; R3 includes a hydrogen atom or a C1 to C3 alkyl group, wherein, when R3 includes a hydrogen atom, at least one of R1 and R2 includes a branched alkyl group; In formula (II), R4 to R6 each independently include C1 to C8 alkyl groups; R7 and R8 each independently include a hydrogen atom or a C1 to C3 alkyl group, wherein, when R7 and R8 both include hydrogen atoms, at least one of R4 to R6 includes a branched alkyl group; In formula (III), R9 to R 12 Each independently comprises a C1 to C8 alkyl group; R 13 To R 15 Each independently includes a hydrogen atom or a C1 to C3 alkyl group, Among them, when R 13 To R 15 When all include hydrogen atoms, R9 to R 12 At least one of the alkyl groups includes a branched alkyl group.

4. The electrolyte according to claim 3, wherein The compound represented by formula (I) includes at least one of the compounds represented by formula (I-1) to the compounds represented by formula (I-3), 5. The electrolyte according to claim 3, wherein The compound represented by formula (II) includes at least one of the compounds represented by formula (II-1) to the compounds represented by formula (II-8), 6. The electrolyte according to claim 3, wherein The compound represented by formula (III) includes at least one of the compounds represented by formula (III-1) to the compounds represented by formula (III-4), 7. The electrolyte according to any one of claims 1 to 6, wherein The unsubstituted first nitrogen-containing alkane includes an unsubstituted nitrogen-containing cyclic alkane, which includes a cyclic structure and at least two branched alkyl groups connected to carbon atoms in the cyclic structure, the nitrogen atom in the cyclic structure is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms.

8. The electrolyte according to claim 7, wherein The unsubstituted nitrogen-containing cyclic alkane includes a compound represented by formula (IV), In formula (IV), R 16 including C1 to C8 alkyl groups; R 17 including a hydrogen atom or a C1 to C3 alkyl group, Among them, when R 17 When hydrogen atoms are included, R 17 including branched chain alkyl groups; Further optionally, the compound represented by formula (IV) includes at least one of the compound represented by formula (IV-1) and the compound represented by formula (IV-4), 9. The electrolyte according to claim 7, wherein The unsubstituted nitrogen-containing cyclic alkane includes a compound represented by formula (V), In formula (IV), R 18 and R 19 Each independently comprises a C1 to C8 alkyl group; R 20 and R 21 Each independently includes a hydrogen atom or a C1 to C3 alkyl group, Among them, when R 20 and R 21 When all include hydrogen atoms, R 18 To R 19 At least one of the following comprises a branched alkyl group; Optionally, the compound represented by formula (V) includes at least one of the compounds represented by formula (V-1) to the compounds represented by formula (V-6), 10. The electrolyte according to any one of claims 1 to 9, wherein The substituted nitrogen-containing linear alkane includes at least one halogen atom; Optionally, the substituted nitrogen-containing linear alkane comprises at least one of the compounds represented by formula (A) to the compounds represented by formula (C), In formula (A), Q1 and Q2 each independently include a substituted or unsubstituted C1 to C8 alkyl group; Q3 includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group; and at least one of Q1 to Q3 is substituted by a halogen atom; In formula (B), Q4 to Q6 each independently include a substituted or unsubstituted C1 to C8 alkyl group; Q7 and Q8 each independently include a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group; and at least one of Q4 to Q8 is substituted by a halogen atom; In formula (C), Q9 to Q 12 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group; Q 13 To Q 15 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group; And Q9 to Q 15 At least one of them is substituted by a halogen atom.

11. The electrolyte according to claim 10, wherein The compound represented by formula (A) includes at least one of the compounds represented by formula (A-1) to the compounds represented by formula (A-3), 12. The electrolyte according to claim 10, wherein The compound represented by formula (B) includes at least one of the compounds represented by formula (B-1) to the compounds represented by formula (B-4), 13. The electrolyte according to claim 10, wherein The compound represented by formula (C) includes at least one of the compounds represented by formula (C-1) to the compounds represented by formula (C-3), 14. The electrolyte according to any one of claims 1 to 13, wherein The substituted first nitrogen-containing alkane includes a substituted nitrogen-containing cyclic alkane, wherein the substituted nitrogen-containing cyclic alkane includes a cyclic structure, wherein a nitrogen atom in the cyclic structure is connected to a carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms. The nitrogen-containing cyclic alkane is substituted by a halogen atom, and the halogen atom substitution position is a carbon atom position indirectly connected to the nitrogen atom.

15. The electrolyte according to claim 14, wherein The nitrogen-containing cyclic alkane includes a compound represented by formula (D), In formula (D), Q 16 including substituted or unsubstituted C1 to C8 alkyl groups; Q 17 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups, And, Q 16 and Q 17 At least one of them is substituted by a halogen atom; The compound represented by formula (D) includes at least one of the compound represented by formula (D-1) and the compound represented by formula (D-2), 16. The electrolyte according to claim 14, wherein The nitrogen-containing cyclic alkane includes a compound represented by formula (E), In formula (E), Q 18 and Q 19 including substituted or unsubstituted C1 to C8 alkyl groups; Q 20 and Q 21 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups, And, Q 18 To Q 21 At least one of them is substituted by a halogen atom; Optionally, the compound represented by formula (E) includes at least one of the compound represented by formula (E-1) and the compound represented by formula (E-2), 17. The electrolyte according to claim 14, wherein Based on the total mass of the organic solvent in the electrolyte, the mass percentage of the substituted or unsubstituted first nitrogen-containing alkane is greater than or equal to 20% and less than 100%, optionally 40% to 80%, and further optionally 50% to 65%.

18. The electrolyte according to any one of claims 1 to 17, further comprising a second nitrogen-containing alkane, wherein the nitrogen atom in the second nitrogen-containing alkane is connected to the carbon atom by a covalent single bond, and the nitrogen atom is located between two adjacent carbon atoms, wherein: At least one of the carbon atoms adjacent to the nitrogen atom is substituted with a halogen atom; Optionally, the second nitrogen-containing alkane comprises at least one of the compounds represented by formula (1) to the compounds represented by formula (5), In formula (1), M1 and M2 each independently include a substituted or unsubstituted C1 to C8 alkyl group; M3 includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group; and at least one of M1 to M3 is substituted by a halogen atom, and the halogen atom is connected to the carbon atom adjacent to the nitrogen atom; In formula (2), M4 to M6 each independently include substituted or unsubstituted C1 to C8 alkyl groups; M7 and M8 each independently include a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group; and at least one of M4 to M8 is substituted by a halogen atom, and the halogen atom is connected to the carbon atom adjacent to the nitrogen atom; In formula (3), M9 to M 12 Each independently includes a substituted or unsubstituted C1 to C8 alkyl group; M 13 To M 15 Each independently includes a hydrogen atom, or a substituted or unsubstituted C1 to C3 alkyl group; And M9 to M 15 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom; In formula (4), M 16 including substituted or unsubstituted C1 to C8 alkyl groups; M 17 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups, And M 16 and M 17 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom; In formula (5), M 18 and M 19 including substituted or unsubstituted C1 to C8 alkyl groups; M 20 and M 21 including hydrogen atoms, substituted or unsubstituted C1 to C3 alkyl groups, And M 18 To M 21 At least one of them is substituted by a halogen atom, which is attached to the carbon atom adjacent to the nitrogen atom; Further optionally, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the second nitrogen-containing alkane is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%.

19. The electrolyte according to any one of claims 1 to 18, wherein the electrolyte further comprises a fluorinated solvent, the fluorinated solvent comprising at least one of a fluorinated ether solvent, a fluorinated aromatic solvent, and a fluorinated saturated alkane solvent; Optionally, based on the total mass of the organic solvent in the electrolyte, the mass percentage of the fluorinated solvent is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%.

20. The electrolyte according to any one of claims 1 to 19, further comprising at least one of an ester solvent and an ether solvent; Optionally, The ester solvent comprises at least one of ethylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, methyl trifluoroethyl carbonate, ethyl trifluoroethyl carbonate, di(2,2,2-trifluoroethyl) carbonate, methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl 2,2,2-trifluoroacetate, and ethyl 2,2,2-trifluoroacetate; The ether solvent includes at least one of methyl ether, ethyl ether, propyl ether, butyl ether, methyl ethyl ether, methyl propyl ether, methyl butyl ether, ethyl propyl ether, ethyl butyl ether, propyl butyl ether, dimethoxymethane, diethoxymethane, dipropoxymethane, dimethoxyethane, dimethoxypropane, diethoxyethane, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, tetrahydropyran, 1,3-dioxane, and 1,4-dioxane; Further optionally, based on the total mass of the organic solvent in the electrolyte, the total mass percentage of the ester solvent and the ether solvent is 0% to 40%; optionally 10% to 30%; further optionally 15% to 25%.

21. The electrolyte according to any one of claims 1 to 20, wherein the electrolyte further comprises a lithium salt, and the lithium salt may include at least one of lithium bis(fluorosulfonyl)imide (LiFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiOTF), lithium difluorophosphate (LiDFP), lithium bis(oxalatoborate) (LiBOB), lithium difluorooxalatoborate (LiDFOB), lithium difluorobis(oxalatophosphate) and lithium tetrafluorooxalatophosphate, and may be lithium bis(fluorosulfonyl)imide; Optionally, the molar concentration of the lithium salt is 0.5 mol / L to 4 mol / L, optionally 0.8 mol / L to 2.4 mol / L, further optionally 1.2 mol / L to 1.8 mol / L.

22. The electrolyte according to any one of claims 1 to 21, wherein the electrolyte further comprises an additive, wherein the additive comprises at least one of propane sultone, vinyl nitrate, vinyl nitrite, tris(trimethylsilane) phosphate, tris(trimethylsilane) phosphite, tris(trifluoroethyl) phosphate, tris(trifluoroethyl) phosphite, tris(trimethylsilane) borate, dimethyl maleic anhydride, and 1,4-diisocyanatobutyl ester; Optionally, based on the total mass of the electrolyte, the mass percentage of the additive is 0% to 5%; optionally 0.5% to 3%.

23. A battery comprising the electrolyte according to any one of claims 1 to 22.

24. An electrical device comprising the battery as claimed in claim 23.

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