Non-aqueous electrolyte, secondary battery and electric device

Abstract

The invention relates to the technical field of batteries, in particular to a non-aqueous electrolyte, a secondary battery and an electric device. And the non-aqueous electrolyte comprises a cyclic sulfate additive and a phosphate ester or isocyanate additive. The invention also relates to a secondary battery containing the non-aqueous electrolyte and an electric device comprising the secondary battery.

Description

Non-aqueous electrolyte, secondary battery and power-consuming device Technical Field

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

[0002] As environmental issues become increasingly severe, the world's pursuit of "carbon neutrality" is driving all industries towards greener and healthier development. Lithium-ion secondary batteries, as a cleaner energy storage device, are becoming widely used in energy storage power systems such as hydropower, thermal, wind, and solar power stations, as well as in various fields such as electric vehicles, military equipment, and aerospace. Against this backdrop, my country has introduced a number of policies since the 12th Five-Year Plan period to vigorously support the development of new energy-related industries. With the rapid development of the industry, my country's new energy sector has accumulated strength and is booming, with many companies joining the forefront of the new energy battery industry. However, market competition is also becoming increasingly fierce, and consumers and investors are also placing higher demands on battery cycle performance and safety performance.

[0003] Summary of the Invention

[0004] In the field of lithium secondary batteries for automotive use, people are paying more attention to battery endurance and cycle life. In order to achieve better endurance, at the cell level, researchers have tried to use positive and negative electrodes with higher compaction density to increase the energy density of the battery. However, this also brings some problems: higher compaction density will greatly reduce the porosity of the electrode, making it more difficult for the electrolyte to infiltrate the electrode, which can easily cause the polarization of the electrode to increase and the impedance to increase. In addition, the positive and negative electrode particles may also be damaged after high-pressure extrusion, causing problems such as transition metal dissolution and violent negative electrode interface reactions. These problems will greatly reduce the cycle life of the battery.

[0005] In order to solve the above problems, the present application provides a non-aqueous electrolyte, which improves the problems of reduced battery life caused by higher positive and negative electrode compaction density by introducing cyclic sulfonate additives and phosphate or isocyanate additives, thereby obtaining a lithium-ion secondary battery with high energy density and long life.

[0006] The first aspect of the present application provides a non-aqueous electrolyte, comprising a first additive and a second additive, wherein the first additive is a cyclic sulfate compound having a structure represented by general formula (I),

[0007] In the general formula (I), R1, R2, R3 and R4 are each independently selected from any one of a group having a structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group.

[0008] In the general formula (II), R5 and R6 are each independently selected from any one of a group having the structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group;

[0009] R1 and R2 are not hydrogen atoms at the same time and R3 and R4 are not hydrogen atoms at the same time;

[0010] The second additive is selected from a phosphate compound, an isocyanate compound or a combination thereof;

[0011] The phosphate compound has a structure shown in general formula (III):

[0012] In the general formula (III), R1, R2, R3, R4, and R5 are each independently selected from any one of a group having a structure represented by the general formula (IV), a hydrogen atom, a C1-C6 alkyl group, a halogen atom, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C6-C10 aryl group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, a hydroxyl group, a sulfonic acid group, and a tri(C1-C6 alkyl)silyl group;

[0013] In the general formula (IV), R6, R7, and R8 are each independently selected from any one of a hydrogen atom, a C1-C6 alkyl group, a halogen atom, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C6-C10 aryl group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group;

[0014] The isocyanate compound has a structure shown in general formula (V):

[0015] In the general formula (V), R1 is selected from unsubstituted or substituted by one or more R a Substituted groups: C2-C10 alkylene, C2-C10 heteroalkylene, C6-C18 arylene, C2-C18 heteroarylene, C3-C18 alicyclic group, C3-C18 hetero alicyclic group,

[0016] The one or more R aEach is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C10 ester group, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, and a C2-C10 alkoxy group;

[0017] In the general formula (V), n is 1, 2 or 3.

[0018] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group,

[0019] In the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group.

[0020] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group and a cyano group.

[0021] In some embodiments, in the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom and a C1-C3 alkyl group.

[0022] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a cyano group.

[0023] In some embodiments, in the cyclic sulfate compound, R 5 and R 6Each is independently selected from any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group and an isopropyl group.

[0024] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0025] Wherein, X is a F atom, a Cl atom or a Br atom.

[0026] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0027] In some embodiments, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0028] In some embodiments, the mass content of the cyclic sulfate ester compound in the non-aqueous electrolyte is W1, wherein 0.005%≤W1≤10%, optionally 0.05%≤W1≤5%.

[0029] In some embodiments, in the phosphate ester compound, R1, R2, R3, R4, and R5 are each independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C6-C10 aryl group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group, a hydroxyl group, a sulfonic acid group, and a tri(C1-C3 alkyl)silyl group;

[0030] In the general formula (IV), R6, R7, and R8 are each independently selected from any one of a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C6-C10 aryl group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group, and a sulfonic acid group.

[0031] In some embodiments, in the phosphate compound, R1, R2, R3, R4, and R5 are each independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 alkoxy group, and a tri(C1-C3 alkyl)silyl group.

[0032] In some embodiments, in the general formula (IV), R6, R7, and R8 are each independently selected from any one of a hydrogen atom, a C1-C3 alkyl group, and a C1-C3 alkoxy group.

[0033] In some embodiments, the group represented by the structure of formula (IV) is selected from any one of the following groups:

[0034] In some embodiments, the phosphate compound is selected from any one or more of the following compounds:

[0035] In some embodiments, in the isocyanate compound, R1 is selected from unsubstituted or substituted by one or more R a Substituted groups include: C2-C6 alkylene, C2-C6 heteroalkylene, C6-C10 arylene, C2-C10 heteroarylene, C4-C6 alicyclic group, and C4-C6 hetero alicyclic group.

[0036] In some embodiments, the one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C6 ester group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, and a C2-C6 alkoxy group.

[0037] In some embodiments, the one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C3 ester group, a C1-C3 alkyl group, a C2-C3 alkenyl group, a C2-C3 alkynyl group, and a C2-C3 alkoxy group.

[0038] In some embodiments, in the isocyanate compound, R1 is selected from unsubstituted or substituted by one or more R a The following groups substituted: C2-C6 alkylene, C6-C10 arylene, C4-C6 alicyclic group; the one or more R a Each is independently selected from a halogen atom, a C1 to C3 alkyl group;

[0039] In some embodiments, the isocyanate compound is selected from any one or more of the following compounds:

[0040] In some embodiments, the mass proportion of the second additive in the non-aqueous electrolyte is W2, wherein 0.01%≤W2≤10%, optionally 0.1%≤W2≤8%, optionally 0.3%≤W2≤5%.

[0041] The second aspect of the present application provides a secondary battery comprising any non-aqueous electrolyte described in the first aspect of the present application, and further comprising a positive electrode sheet and a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode material layer containing a negative electrode active material.

[0042] In some embodiments, the porosity of the negative electrode material layer is 30% to 45%, optionally 37% to 42%.

[0043] In some embodiments, the average particle size Dv50 of the negative electrode active material is 3 to 25 μm, optionally 5 μm≤Dv50≤20 μm, optionally 7 μm≤Dv50≤15 μm.

[0044] In some embodiments, the coating weight per unit area of ​​the negative electrode sheet is CW, 2 mg / cm 2 ≤CW≤13mg / cm 2 , optionally, 5 mg / cm 2 ≤CW≤10mg / cm 2 .

[0045] A third aspect of the present application provides an electrical device, comprising a secondary battery, wherein the secondary battery comprises any secondary battery described in the second aspect of the present application.

[0046] The non-aqueous electrolyte provided in this application can extend the cycle storage life of secondary batteries at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. 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 creative work.

[0048] FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0049] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .

[0050] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0051] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0052] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0053] FIG6 is a schematic diagram of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0054] In the drawings, the drawings are not drawn to scale.

[0055] Explanation of reference numerals: 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cover assembly. DETAILED DESCRIPTION

[0056] The following detailed description of the embodiments of the present application is provided in conjunction with the accompanying drawings and examples. The following detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of the present application, but are not intended to limit the scope of the present application, that is, the present application is not limited to the described embodiments.

[0057] Below, the embodiments of the non-aqueous electrolyte, secondary battery and electrical device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be 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.

[0058] " range " disclosed in the present application is limited in the form of lower limit and upper limit, and 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 special range. The scope limited in this way can be to include end value or not include end value, and can be arbitrarily combined, that is, any lower limit can form a range with any upper limit combination. For example, if the scope of 60-120 and 80-110 is listed for specific parameters, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range value 1 and 2 are listed, and if the maximum range value 3,4 and 5 are listed, then the following range can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this 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 all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this 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.

[0059] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0060] 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.

[0061] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating 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.

[0062] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0063] Unless otherwise specified, the term "or" is used in this application to be inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, the condition "A or B" is satisfied if any of the following conditions are met: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0064] [Non-aqueous electrolyte]

[0065] The first aspect of the present application provides a non-aqueous electrolyte, comprising a first additive and a second additive, wherein the first additive is a cyclic sulfate compound having a structure represented by general formula (I),

[0066] In the general formula (I), R1, R2, R3 and R4 are each independently selected from any one of a group having a structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group.

[0067] In the general formula (II), R5 and R6 are each independently selected from any one of a group having the structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group;

[0068] R1 and R2 are not hydrogen atoms at the same time and R3 and R4 are not hydrogen atoms at the same time;

[0069] The second additive is selected from a phosphate compound, an isocyanate compound or a combination thereof;

[0070] The phosphate compound has a structure shown in general formula (III):

[0071] In the general formula (III), R1, R2, R3, R4, and R5 are each independently selected from any one of a group having a structure represented by the general formula (IV), a hydrogen atom, a C1-C6 alkyl group, a halogen atom, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C6-C10 aryl group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, a hydroxyl group, a sulfonic acid group, and a tri(C1-C6 alkyl)silyl group;

[0072] In the general formula (IV), R6, R7, and R8 are each independently selected from any one of a hydrogen atom, a C1-C6 alkyl group, a halogen atom, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C6-C10 aryl group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group;

[0073] The isocyanate compound has a structure shown in general formula (V):

[0074] In the general formula (V), R1 is selected from unsubstituted or substituted by one or more R a Substituted groups: C2-C10 alkylene, C2-C10 heteroalkylene, C6-C18 arylene, C2-C18 heteroarylene, C3-C18 alicyclic group, C3-C18 hetero alicyclic group,

[0075] The one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C10 ester group, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, and a C2-C10 alkoxy group;

[0076] In the general formula (V), n is 1, 2 or 3.

[0077] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group,

[0078] In the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group.

[0079] The non-aqueous electrolyte provided by the present application contains a variety of additives. Among them, the cyclic sulfate additive can participate in the formation of a film at the negative electrode interface during the first charge process. The film is mainly composed of a mixture of inorganic and organic components. The SEI formed by the cyclic sulfate additive has a denser structure and is more conductive to Li + The SEI film has a stronger ability to protect the negative electrode, thus reducing the negative electrode interfacial impedance. Furthermore, the SEI film provides strong protection for the negative electrode, improving the battery's cycle life at high temperatures. However, at high temperatures, LiPF6 easily decomposes to produce HF, which causes continuous damage to the SEI. Introducing phosphate or isocyanate additives into the electrolyte can reduce the acid content in the electrolyte and extend the battery's cycle life at high temperatures.

[0080] The cyclic sulfate rings used in the present application are all five-membered rings, which can form a denser SEI film.

[0081] In the above general formula (I), R 1 、R 2 、R 3 and R 4 It can be an alkyl group or a substituent containing F or N. By introducing substituents such as alkyl groups, an elastic SEI film with a longer organic chain can be generated at the negative electrode, which can cope with the volume change of the negative electrode during the cycle and avoid the destruction of the SEI film; the introduction of substituents such as F and N can participate in the film formation at the negative electrode, generate a SEI film rich in more inorganic components such as LiF and Li3N, improve the mechanical strength of the SEI film, and then improve the stability of the negative electrode SEI film, thereby achieving the purpose of further improving the battery cycle performance.

[0082] The above-mentioned alkyl group may be a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, including but not limited to methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, cyclopropyl, cyclobutane, etc.; the alkyl group in the above-mentioned haloalkyl group includes but is not limited to a straight-chain alkyl group, a branched-chain alkyl group or a cycloalkyl group, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, cyclopropyl, cyclobutane, etc.; the halogen atom may be a fluorine atom, a chlorine atom or a bromine atom, and the halogen atom replaces any one or more hydrogen atoms on the alkyl group; the above-mentioned alkoxy group includes but is not limited to a cyclopropane group, an oxetane group, etc.; the halogen atom in the haloalkoxy group may be a fluorine atom, a chlorine atom or a bromine atom, and the halogen atom replaces any one or more hydrogen atoms on the alkoxy group; the alkenyl group includes but is not limited to -CH=CH2, -CH=CH2CH3, -CH2CH=CH2, -CH2CH=CH2CH3; the ester group includes but is not limited to methyl formate, ethyl formate, ethyl acetate, methyl propionate, ethyl propionate, propyl propionate, etc.

[0083] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group and a cyano group.

[0084] In some embodiments, in the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom and a C1-C3 alkyl group.

[0085] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a cyano group.

[0086] In some embodiments, in the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group and an isopropyl group.

[0087] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0088] Wherein, X is a F atom, a Cl atom or a Br atom.

[0089] In some embodiments, the group represented by the general formula (II) is selected from any one of the following groups:

[0090] In some embodiments, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0091] The preparation method of the cyclic sulfate ester compound is simpler, easier to promote and implement in industry, and has a more stable effect on improving the cycle storage performance of secondary batteries.

[0092] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0093] R 1 and R 2 At the same time, it is a hydrogen atom and R 3 and R 4 One is a hydrogen atom and the other is any one of a group having a structure represented by general formula (II), a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group, and R 5 and R 6 Not all hydrogen atoms.

[0094] In some embodiments, in the cyclic sulfate compound, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0095] R 3 and R 4 At the same time, it is a hydrogen atom and R 1 and R 2 One is a hydrogen atom and the other is any one of a group having a structure represented by general formula (II), a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group, and R 5 and R 6 Not all hydrogen atoms.

[0096] In some embodiments, in the cyclic sulfate compound, R 5 and R 6 Each is independently selected from groups other than the structural group represented by the general formula (II).

[0097] In some embodiments, the mass content of the cyclic sulfate ester compound in the non-aqueous electrolyte is W1, wherein 0.005% ≤ W1 ≤ 10%, and optionally 0.05% ≤ W1 ≤ 5%. When the mass content of the cyclic sulfate ester additive in the electrolyte is within the above preferred range, the battery cell has better cycle storage performance.

[0098] In some embodiments, W1 can be less than 0.001%, or 0.001% to 0.005%, 0.005% to 0.01%, 0.01% to 0.05%, 0.05% to 0.1%, 0.1% to 0.2%, 0.2% to 0.3%, 0.3% to 0.5%, 0.5% to 1%, 1% to 2%, 2% to 3%, 3% to 4%, 4% to 5%, 5% to 8%, 8% to 10%, 10% to 15%, or greater than 15%.

[0099] The preparation method of the cyclic sulfate compound having the structure shown in the general formula (I) of the present application refers to the following synthetic route:

[0100] The reaction temperature of the first step is controlled at 30-60° C.; the reaction temperature of the second step is controlled at 10-30° C. The second step is catalyzed by a catalyst such as ruthenium trichloride trihydrate, and the oxidant can be sodium hypochlorite, ozone, etc.

[0101] In some embodiments, in the phosphate ester compound, R1, R2, R3, R4, and R5 are each independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C6-C10 aryl group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group, a hydroxyl group, a sulfonic acid group, and a tri(C1-C3 alkyl)silyl group;

[0102] In the general formula (IV), R6, R7, and R8 are each independently selected from any one of a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C6-C10 aryl group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group, and a sulfonic acid group.

[0103] In some embodiments, in the phosphate compound, R1, R2, R3, R4, and R5 are each independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 alkoxy group, and a tri(C1-C3 alkyl)silyl group.

[0104] In some embodiments, in the general formula (IV), R6, R7, and R8 are each independently selected from any one of a hydrogen atom, a C1-C3 alkyl group, and a C1-C3 alkoxy group.

[0105] In some embodiments, the group of the structure shown in formula (IV) is selected from any one of the following groups:

[0106] In some embodiments, the phosphate compound is selected from any one or more of the following compounds:

[0107] In some embodiments, in the isocyanate compound, R1 is selected from unsubstituted or substituted by one or more R a Substituted groups include: C2-C6 alkylene, C2-C6 heteroalkylene, C6-C10 arylene, C2-C10 heteroarylene, C4-C6 alicyclic group, and C4-C6 hetero alicyclic group.

[0108] In some embodiments, the one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C6 ester group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, and a C2-C6 alkoxy group.

[0109] In some embodiments, the one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C3 ester group, a C1-C3 alkyl group, a C2-C3 alkenyl group, a C2-C3 alkynyl group, and a C2-C3 alkoxy group.

[0110] In some embodiments, in the isocyanate compound, R1 is selected from unsubstituted or substituted by one or more R a The following groups substituted: C2-C6 alkylene, C6-C10 arylene, C4-C6 alicyclic group; the one or more R a Each is independently selected from a halogen atom, a C1 to C3 alkyl group;

[0111] In some embodiments, the isocyanate compound is selected from any one or more of the following compounds:

[0112] The preparation method of the phosphate or isocyanate compound is simpler, easier to promote and implement in industry, and has a more stable effect on improving the cycle storage performance of secondary batteries.

[0113] In some embodiments, the mass percentage of the second additive in the non-aqueous electrolyte is W2, wherein 0.01% ≤ W2 ≤ 10%, optionally 0.1% ≤ W2 ≤ 8%, and optionally 0.3% ≤ W2 ≤ 5%. When the mass percentage of the second additive in the electrolyte is within the above preferred range, the battery cell has better cycle storage performance.

[0114] In some embodiments, W2 can be less than 0.001%, or 0.001% to 0.005%, 0.005% to 0.01%, 0.01% to 0.05%, 0.05% to 0.1%, 0.1% to 0.2%, 0.2% to 0.3%, 0.3% to 0.5%, 0.5% to 1%, 1% to 2%, 2% to 3%, 3% to 4%, 4% to 5%, 5% to 6%, 6% to 8%, 8% to 9%, 9% to 10%, 10% to 12%, or greater than 12%.

[0115] In some embodiments, the non-aqueous electrolyte used in the present invention also includes an electrolyte. As long as it is an electrolyte that can be generally used in non-aqueous electrolytes, it can be considered for application to the non-aqueous electrolyte of the present application. Those skilled in the art can make a selection based on the battery system in which the non-aqueous electrolyte is applied, such as selecting a conventional electrolyte suitable for secondary batteries. In some embodiments, the electrolyte includes an alkali metal salt electrolyte; the electrolyte includes a lithium salt; optionally, the lithium salt includes one or more selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide. Each of the above lithium salts can be used alone or in combination of two or more.

[0116] The content of electrolyte in the non-aqueous electrolyte can refer to the electrolyte content in conventional non-aqueous electrolyte. In some embodiments, the electrolyte content in the non-aqueous electrolyte is 0.1 mol / L-5 mol / L, for example, it can be 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 4 mol / L or 5 mol / L. In some embodiments, the non-aqueous electrolyte further comprises a non-aqueous solvent. Optionally, the non-aqueous solvent comprises any one or more selected from the group consisting of cyclic carbonates, chain carbonates, nitrile solvents, ketone solvents and sulfone solvents; further optionally, the non-aqueous solvent comprises one or more selected from the group consisting of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methylpropyl carbonate, ethylpropyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, tetrahydrofuran, ethylene glycol dimethyl ether, dioxolane, acetone, acetonitrile and butyronitrile. The above non-aqueous solvents can be used alone or in combination of two or more. For example, in order to improve the load characteristics and low-temperature characteristics of the secondary battery, a mixed solvent of cyclic carbonate and chain carbonate can be used. In some embodiments, EC+EMC (ethylene carbonate+ethyl methyl carbonate) is used as the non-aqueous solvent.

[0117] When the non-aqueous electrolyte of the present application is applied to a solid battery, a solid solvent such as dimethyl sulfone may be used.

[0118] In addition to the aforementioned additives, the additives may also include negative electrode film-forming additives, positive electrode film-forming additives, and additives capable of improving certain battery properties, such as additives that improve battery overcharge performance, additives that improve battery high or low temperature performance, etc. In some embodiments, the aforementioned additives further include, but are not limited to, one or more selected from the group consisting of sulfate compounds, sulfite compounds, sultone compounds, disulfonic acid compounds, nitrile compounds, aromatic compounds, isocyanate compounds, phosphazene compounds, cyclic acid anhydride compounds, phosphite compounds, phosphate compounds, borate compounds, and carboxylate compounds.

[0119] [Secondary battery]

[0120] The second aspect of the present application provides a secondary battery. A secondary battery, also known as a rechargeable battery or storage battery, refers to a battery that can be activated by charging the active material after the battery is discharged and continued to be used. Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. During the battery charging and discharging process, active ions (such as lithium ions) are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, and mainly plays the role of preventing the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet, and mainly plays the role of conducting active ions.

[0121] [Negative electrode]

[0122] The secondary battery provided in the present application may include a negative electrode plate, wherein the negative electrode plate includes a negative electrode material layer, and the negative electrode material layer includes a negative electrode active material.

[0123] The porosity of the negative electrode material layer indicates the amount of pores between the particles within the electrode sheet. In some embodiments, the porosity of the negative electrode material layer is 30% to 45%, and optionally 37% to 42%. When the porosity of the negative electrode material layer is within this range, the number of pores between the particles within the electrode sheet is appropriate, the particle structure is less susceptible to extrusion damage, electrolyte infiltration is better, and the long-term cycling performance of the battery cell is better, while the energy density of the battery cell is not affected.

[0124] In some embodiments, the porosity of the negative electrode material layer is less than 25%, or is 25% to 30%, 30% to 35%, 35% to 37%, 37% to 39%, 39% to 40%, 40% to 42%, 42% to 44%, 44% to 45%, 45% to 48%, or greater than 48%.

[0125] Porosity P of the negative electrode n It can be obtained by the gas filling method. For example, He gas can be filled into the pores of the negative electrode sheet to measure the real volume V2 of the negative electrode sheet. Then, the apparent volume V1 of the negative electrode sheet can be calculated by the coating weight of the negative electrode sheet and the compaction density of the negative electrode sheet. The porosity P of the negative electrode sheet is n =(V1-V2) / V1×100%

[0126] The particle size of the negative electrode active material can be represented by Dv50, which refers to the particle size corresponding to the cumulative volume percentage reaching 50%, i.e., the median particle size of the volume distribution. In some embodiments, the average particle size Dv50 of the negative electrode active material used in the present invention is 3 to 25 μm, optionally 5 μm ≤ Dv50 ≤ 20 μm, and optionally 7 μm ≤ Dv50 ≤ 15 μm. When the Dv50 of the negative electrode active material is within the above preferred range, it is beneficial to form a uniform surface when coating and preparing the electrode sheet, and it is also beneficial to reduce side reactions between the electrode and the electrolyte, reduce the loss of initial battery capacity, and achieve better battery performance.

[0127] In some embodiments, Dv50 can be less than 0.5 μm, or 0.5 μm to 1 μm, 1 μm to 1.5 μm, 1.5 μm to 2 μm, 2 μm to 3 μm, 3 μm to 5 μm, 5 μm to 7 μm, 7 μm to 10 μm, 10 μm to 15 μm, 15 μm to 18 μm, 18 μm to 20 μm, 20 μm to 22 μm, 22 μm to 25 μm, 25 μm to 30 μm, or greater than 30 μm.

[0128] Dv50 can be measured using instruments and methods known in the art. For example, a Malvern Mastersizer 3000 laser diffraction particle size distribution analyzer (available from Malvern Instruments Ltd., UK) is used to measure the particle size distribution according to the particle size distribution laser diffraction method GB / T 19077-2016 to obtain Dv50.

[0129] The negative electrode sheet can be made by coating the negative electrode slurry on the surface of the negative electrode current collector. The coating weight per unit area of ​​the electrode sheet represents the dry weight of the coating slurry per unit area of ​​the current collector surface. In some embodiments, the coating weight per unit area of ​​the negative electrode sheet is CW, 2 mg / cm 2 ≤CW≤13mg / cm 2 , optionally, 5 mg / cm 2 ≤CW≤10mg / cm 2 When the coating weight per unit area of ​​the negative electrode film is within the above range, the energy density of the battery can be maintained at a relatively good level while maintaining good battery dynamics.

[0130] In some embodiments, CW can be less than 1.5 mg / cm 2 , or 1.5 mg / cm 2 ~2mg / cm 2 , 2mg / cm 2 ~3mg / cm 2 , 3mg / cm 2 ~5mg / cm 2 , 5mg / cm 2~6mg / cm 2 , 6mg / cm 2 ~8mg / cm 2 , 8 mg / cm 2 ~10mg / cm 2 、10mg / cm 2 ~12mg / cm 2 , 12mg / cm 2 ~13mg / cm 2 、13mg / cm 2 ~15mg / cm 2 , or greater than 15 mg / cm 2 .

[0131] The coating weight per unit area of ​​the electrode sheet can be measured by the following method:

[0132] Take several pieces of current collector foil, each of which has an area of ​​S, weigh them respectively, take the average value, and record it as M1; take several pieces of electrode sheets coated with the same weight of slurry, coat them evenly, dry them at 120°C for 1 hour, and after testing to find that they are basically free of solvent, weigh the current collector foils with slurry coated on one side after drying, take the average value, and record it as M2; then the coating weight of the active material layer on one side of the current collector CW = (M2-M1) / S.

[0133] The negative electrode sheet may include a negative electrode current collector and a negative electrode material layer disposed on at least one surface of the negative electrode current collector. For example, the negative electrode current collector may have two opposing surfaces in its thickness direction, and the negative electrode material layer may be disposed on either or both of the two opposing surfaces of the negative electrode current collector.

[0134] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer base material. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy, etc.) on a polymer base material (such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0135] In some embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As an example, the negative electrode active material may include at least one of the following materials: graphite (such as artificial graphite, natural graphite), soft carbon, hard carbon, silicon-based materials, tin-based materials and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites and silicon alloys. The tin-based material can be selected from at least one of elemental tin, tin oxides and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0136] In some embodiments, the negative electrode material layer may further include a binder. For example, the binder may be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0137] In some embodiments, the negative electrode material layer may further include a conductive agent. For example, the conductive agent may be selected from at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0138] In some embodiments, the negative electrode material layer may optionally further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0139] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained.

[0140] [Positive electrode]

[0141] The secondary battery provided herein may include a positive electrode sheet, which generally includes a positive electrode current collector and a positive electrode material layer disposed on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode material layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0142] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base and a metal layer formed on at least one surface of the polymer material base. The composite current collector may be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0143] In some embodiments, the positive electrode material layer may include a positive electrode active material. Positive electrode active materials for batteries that are well known in the art may be used. As an example, the positive electrode active material may include at least one of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, lithium cobalt oxide (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (such as LiNi 0.85 Co 0.15 Al 0.05O2) and its modified compounds. Examples of olivine-structured lithium-containing phosphates may include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4 (also referred to as LFP)), a composite material of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0144] In some embodiments, the positive electrode material layer may further optionally include a binder. As an example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0145] In some embodiments, the positive electrode material layer may further include a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0146] In some embodiments, the positive electrode sheet can be prepared by the following method: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent (such as N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is coated on the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0147] [Isolation film]

[0148] In some embodiments, the secondary battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical and mechanical stability can be selected.

[0149] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0150] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a lamination process.

[0151] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0152] In some embodiments, the outer packaging of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, or a steel shell. Alternatively, the outer packaging of the secondary battery can be a soft shell, such as a pouch-type soft shell. The soft shell can be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0153] The present application has no particular limitation on the shape of the secondary battery, which may be cylindrical, square, or any other shape. For example, FIG1 shows a secondary battery 5 with a square structure as an example.

[0154] In some embodiments, referring to Figure 2, the outer packaging 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 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can be formed into an electrode assembly 52 through a winding process 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 secondary battery 5 can be one or more, and those skilled in the art can select according to specific actual needs.

[0155] In some embodiments, secondary batteries can be assembled into a battery module. The number of secondary batteries contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0156] Figure 3 shows an example battery module 4. Referring to Figure 3 , within the battery module 4, multiple secondary batteries 5 may be arranged sequentially along the length of the battery module 4. Of course, any other arrangement is also possible. Furthermore, the multiple secondary batteries 5 may be secured together using fasteners.

[0157] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of secondary batteries 5 are received in the receiving space.

[0158] In some embodiments, the battery modules described above may also be assembled into a battery pack. The battery pack may contain one or more battery modules, and the specific number may be selected by those skilled in the art based on the application and capacity of the battery pack.

[0159] Figures 4 and 5 illustrate an example battery pack 1. Referring to Figures 4 and 5 , the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box comprises an upper case 2 and a lower case 3. The upper case 2 can be placed over the lower case 3 to form an enclosed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0160] In addition, the present application also provides an electric device, which includes at least one of the secondary battery, battery module, or battery pack provided in the present application. The secondary battery, battery module, or battery pack can be used as a power source for the electric device, and can also be used as an energy storage unit for the electric device. The electric device may include mobile devices (such as mobile phones, laptops, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc., but is not limited thereto.

[0161] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0162] Figure 6 shows an example of an electric device. This device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the high power and high energy density requirements of the secondary battery, a battery pack or battery module can be used.

[0163] [Example]

[0164] Below, the embodiment of the application is described. The embodiment described below is exemplary, is only used to explain the application, and is not to be construed as limiting the application. Where specific techniques or conditions are not indicated in the embodiment, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents or instruments used that do not indicate the manufacturer are conventional products that can be obtained commercially. The remaining reagents or compound information are recorded in Table 1.

[0165] Table 1

[0166] Synthesis example

[0167] The preparation method of the cyclic sulfate compound having the structure shown in the general formula (I) of the present application refers to the following synthetic route:

[0168] The reaction temperature of the first step is controlled at 30-60° C.; the reaction temperature of the second step is controlled at 10-30° C. The second step is catalyzed by a catalyst such as ruthenium trichloride trihydrate, and the oxidant can be sodium hypochlorite, ozone, etc.

[0169] Synthesis Example 1: Compound 1 Synthesis

[0170] Step 1: Add 300g (2mol) of solid 1,6-dideoxygalactitol to a 5L three-necked flask, start stirring, and add 523g (4.4mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition process. After the addition is completed, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1L of deionized water dropwise, and quickly stir to break up the reaction system. The filtered solid is slurried and washed with deionized water several times until the pH is neutral. The filter cake is dried under reduced pressure at 60°C to obtain intermediate product 1.

[0171] Step 2: To a 3L three-necked flask, 184.2g (0.8mol) of intermediate 1 was added, 1000mL of acetonitrile was added, and 80mg of ruthenium trichloride trihydrate catalyst was added. After nitrogen displacement of the system, the system was cooled to 20°C, stirring was started, and 2000g of 20% sodium hypochlorite aqueous solution was added dropwise within 1h, and the reaction temperature was controlled at 10-20°C. After the addition was complete, the mixture was stirred at 10-20°C for 10min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue. The liquid was separated again, the organic layer was concentrated, and crystallized from acetonitrile to obtain a white powder solid, which was the above-mentioned compound 1. 1H-NMR, CD3CN, δppm 5.42-5.39 (m, 2H), 5.36-5.34 (m, 2H), 1.67-1.65 (d, 6H).

[0172] Synthesis Example 2: Compound 2 Synthesis

[0173] Step 1: Add 356.5g (2mol) of solid 3,4,5,6-octanetrol to a 5L three-necked flask and start stirring. Add 523g (4.4mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition. After the addition is completed, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1L of deionized water dropwise, stir the reaction system rapidly to break it up, and wash the filtered solid with deionized water several times to a neutral pH. Dry the filter cake at 60°C under reduced pressure to obtain intermediate product 2.

[0174] Step 2: 216.2 g (0.8 mol) of intermediate product 2 was added to a 3L three-necked flask, 1000 mL of acetonitrile was added, 80 mg of ruthenium trichloride trihydrate catalyst was added, and after nitrogen replacement of the system, the system was cooled to 20 ° C, stirring was started, and 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C; after the addition was completed, stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 2.

[0175] Synthesis Example 3: Compound 3 Synthesis

[0176] Step 1: Add 328.4 g (2 mol) of solid 2,3,4,5-heptetrol to a 5 L three-necked flask and start stirring. Add 523 g (4.4 mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition. After the addition is complete, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1 L of deionized water dropwise, stir the reaction system rapidly to break it up, and wash the filtered solid with deionized water several times until the pH is neutral. Dry the filter cake at 60°C under reduced pressure to obtain intermediate product 3.

[0177] Step 2: 205 g (0.8 mol) of intermediate 3 was added to a 3L three-necked flask, 1000 mL of acetonitrile was added, and the mixture was stirred until the solid was completely dissolved. 80 mg of ruthenium trichloride trihydrate catalyst was added. After nitrogen displacement of the system, the system was cooled to 20 ° C. and stirring was started. 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C. After the addition was complete, the mixture was stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and the acetonitrile crystals were obtained to obtain compound 3 (163.1 g, yield 82.8%).

[0178] In addition, the synthesis methods of the following compounds refer to Synthesis Example 1, using the corresponding substrates in Table 2 to replace 1,6-dideoxygalactitol.

[0179] Table 2

[0180] Synthesis Example 4: Compound 5 Synthesis

[0181] Step 1: Add 392.4 g (2 mol) of solid 1,2,3,4,5.6-heptanhexaol to a 5 L three-necked flask and start stirring. Add 784.5 g (6.6 mol) of thionyl chloride dropwise to the three-necked flask. Control the temperature at about 15°C during the addition. After the addition is completed, keep the reaction at 45°C for 4 hours. A large amount of pasty solid precipitates from the reaction solution. After cooling, slowly add 1 L of deionized water dropwise, stir the reaction system rapidly to break it up, and wash the filtered solid with deionized water several times to a neutral pH. Dry the filter cake at 60°C under reduced pressure to obtain intermediate product 4.

[0182] Step 2: 140 g (0.4 mol) of intermediate product 4 was added to a 4L three-necked flask, 1000 mL of acetonitrile was added, 110 mg of ruthenium trichloride trihydrate catalyst was added, and after nitrogen replacement of the system, the system was cooled to 20 ° C, stirring was started, and 1500 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C; after the addition was complete, the mixture was stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and the acetonitrile crystals were obtained to obtain compound 5.

[0183] In addition, the synthesis methods of the following compounds refer to Synthesis Example 4, using the corresponding substrates in Table 3 to replace 1,2,3,4,5.6-heptanhexaol.

[0184] Table 3

[0185] Synthesis Example 5: Compound 7 Synthesis

[0186] Step 1: 484 g (2 mol) of solid octitol was added to a 5 L three-necked flask, stirring was started, and 1046 g (8.8 mol) of thionyl chloride was added dropwise to the three-necked flask. The temperature was controlled at about 15 ° C during the addition process. After the addition was completed, the reaction was kept at 45 ° C for 4 hours. A large amount of pasty solid precipitated from the reaction solution. After cooling, 1 L of deionized water was slowly added dropwise, and the reaction system was quickly stirred to break up. The filtered solid was washed with deionized water several times until the pH was neutral. The filter cake was dried under reduced pressure at 60 ° C to obtain intermediate product 5.

[0187] Step 2: 183.2 g (0.4 mol) of intermediate product 5 was added to a 4L three-necked flask, 1000 mL of acetonitrile was added, 150 mg of ruthenium trichloride trihydrate catalyst was added, and after nitrogen replacement of the system, the system was cooled to 20 ° C, stirring was started, and 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h, and the reaction temperature was controlled at 10-20 ° C; after the addition was complete, stirred at 10-20 ° C for 10 min, separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch potassium iodide test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 7.

[0188] Example 1

[0189] Electrolyte composition: Compound 1 is used as the first additive, and its mass content in the electrolyte is 2%; Compound 12 is used as the second additive, and its mass content in the electrolyte is 2%; LiPF6 is used as the electrolyte, and its content in the electrolyte is 10%, and a mixture of EC+EMC (ethylene carbonate+ethyl methyl carbonate) with a volume ratio of 3:7 is used as the solvent.

[0190] Positive electrode preparation:

[0191] The positive electrode active material lithium iron phosphate (LiFePO4), the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are dissolved in the solvent N-methylpyrrolidone (NMP) in a weight ratio of 90:5:5, and are fully stirred and mixed to obtain the positive electrode slurry; the positive electrode slurry is then evenly coated on the positive electrode collector, and then dried, cold pressed, and cut to obtain the positive electrode sheet.

[0192] Negative electrode preparation:

[0193] The negative electrode active material graphite (average particle size Dv50 is 10μm), conductive agent carbon black, binder styrene butadiene rubber (SBR), and thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water at a weight ratio of 90:4:4:2 and mixed evenly to prepare a negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector copper foil once or multiple times, and the negative electrode sheet is obtained after drying, cold pressing, and slitting. The coating weight per unit area (CW) of the negative electrode sheet is 8mg / cm 2 .

[0194] The Dv50 of the negative electrode active material refers to the particle size corresponding to the cumulative volume percentage of the negative electrode active material reaching 50%, that is, the median particle size of the volume distribution, and is measured in μm. Dv50 can be measured using instruments and methods known in the art. For example, a laser diffraction particle size distribution analyzer (Malvern Mastersizer 3000) from Malvern Instruments Ltd. in the UK is used to measure the particle size distribution according to the particle size distribution laser diffraction method GB / T19077-2016 to obtain Dv50.

[0195] The porosity of the negative electrode material layer in the negative electrode sheet is 39%.

[0196] Porosity P of the negative electrode n It can be obtained by the gas filling method. For example, He gas can be filled into the pores of the negative electrode sheet to measure the real volume V2 of the negative electrode sheet. Then, the apparent volume V1 of the negative electrode sheet can be calculated by the coating weight of the negative electrode sheet and the compaction density of the negative electrode sheet. The porosity P of the negative electrode sheet is n =(V1-V2) / V1×100%

[0197] Diaphragm:

[0198] Conventional polypropylene film is used as the separator.

[0199] Lithium-ion battery assembly:

[0200] The positive electrode sheet, separator, and negative electrode sheet are stacked in order, with the separator placed between the positive and negative electrode sheets to serve as an isolation, and then wound to obtain an electrode assembly; the electrode assembly is placed in a battery casing, dried, and then injected with electrolyte, and then undergoes formation, static and other processes to produce a lithium-ion battery.

[0201] Example 2-1

[0202] Compound 2 was used to replace Compound 1 as the first additive, and the rest was the same as in Example 1.

[0203] Example 2-2

[0204] Compound 3 was used to replace Compound 1 as the first additive, and the rest was the same as in Example 1.

[0205] Example 2-3

[0206] Compound 4 was used to replace Compound 1 as the first additive, and the rest was the same as in Example 1.

[0207] Examples 2-4

[0208] Compound 5 was used to replace Compound 1 as the first additive, and the rest was the same as in Example 1.

[0209] Examples 2-5

[0210] Compound 6 was used to replace Compound 1 as the first additive, and the rest was the same as in Example 1.

[0211] Examples 2-6

[0212] Compound 7 was used instead of Compound 1 as the first additive, and the rest was the same as in Example 1.

[0213] Example 3-1

[0214] The mass content of the first additive compound 1 was adjusted to 0.001%, and the rest was the same as in Example 1.

[0215] Example 3-2

[0216] The mass content of the first additive compound 1 is adjusted to 0.01%, and the rest is the same as in Example 1.

[0217] Example 3-3

[0218] The mass content of the first additive compound 1 is adjusted to 4%, and the rest is the same as in Example 1.

[0219] Examples 3-4

[0220] The mass content of the first additive compound 1 is adjusted to 8%, and the rest is the same as in Example 1.

[0221] Examples 3-5

[0222] The mass content of the first additive compound 1 is adjusted to 15%, and the rest is the same as in Example 1.

[0223] Example 4-1

[0224] Compound 9 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0225] Example 4-2

[0226] Compound 10 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0227] Example 4-3

[0228] Compound 11 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0229] Example 4-4

[0230] Compound 13 was used to replace Compound 12 as the second additive, and the rest was the same as in Example 1.

[0231] Examples 4-5

[0232] Compound 14 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0233] Examples 4-6

[0234] Compound 15 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0235] Examples 4-7

[0236] Compound 16 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0237] Examples 4-8

[0238] Compound 17 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0239] Examples 4-9

[0240] Compound 18 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0241] Examples 4-10

[0242] Compound 19 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0243] Examples 4-11

[0244] Compound 20 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0245] Examples 4-12

[0246] Compound 21 was used to replace Compound 12 as the second additive, and the rest was the same as in Example 1.

[0247] Examples 4-13

[0248] Compound 22 was used to replace compound 12 as the second additive, and the rest was the same as in Example 1.

[0249] Examples 4-14

[0250] Compound 23 was used to replace compound 12 as the second additive, and the rest was the same as in Example 1.

[0251] Examples 4-15

[0252] Compound 24 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0253] Examples 4-16

[0254] Compound 25 was used instead of Compound 12 as the second additive, and the rest was the same as in Example 1.

[0255] Example 5-1

[0256] The mass content of the second additive compound 12 was adjusted to 0.005%, and the rest was the same as in Example 1.

[0257] Example 5-2

[0258] The mass content of the second additive compound 12 was adjusted to 0.05%, and the rest was the same as in Example 1.

[0259] Example 5-3

[0260] The mass content of the second additive compound 12 was adjusted to 0.2%, and the rest was the same as in Example 1.

[0261] Example 5-4

[0262] The mass content of the second additive compound 12 was adjusted to 4%, and the rest was the same as in Example 1.

[0263] Example 5-5

[0264] The mass content of the second additive compound 12 was adjusted to 6%, and the rest was the same as in Example 1.

[0265] Examples 5-6

[0266] The mass content of the second additive compound 12 was adjusted to 9%, and the rest was the same as in Example 1.

[0267] Examples 5-7

[0268] The mass content of the second additive compound 12 was adjusted to 12%, and the rest was the same as in Example 1.

[0269] Example 6-1

[0270] The porosity of the negative electrode material layer in the negative electrode plate was adjusted to 25%, and the rest was the same as in Example 1.

[0271] Example 6-2

[0272] The porosity of the negative electrode material layer in the negative electrode plate was adjusted to 35%, and the rest was the same as in Example 1.

[0273] Example 6-3

[0274] The porosity of the negative electrode material layer in the negative electrode plate was adjusted to 40%, and the rest was the same as in Example 1.

[0275] Example 6-4

[0276] The porosity of the negative electrode material layer in the negative electrode plate was adjusted to 44%, and the rest was the same as in Example 1.

[0277] Example 6-5

[0278] The porosity of the negative electrode material layer in the negative electrode plate was adjusted to 48%, and the rest was the same as in Example 1.

[0279] Example 7-1

[0280] The average particle size Dv50 of the negative electrode active material was adjusted to 3 μm, and the rest was the same as in Example 1.

[0281] Example 7-2

[0282] The average particle size Dv50 of the negative electrode active material was adjusted to 6 μm, and the rest was the same as in Example 1.

[0283] Example 7-3

[0284] The average particle size Dv50 of the negative electrode active material was adjusted to 8 μm, and the rest was the same as in Example 1.

[0285] Example 7-4

[0286] The average particle size Dv50 of the negative electrode active material was adjusted to 15 μm, and the rest was the same as in Example 1.

[0287] Example 7-5

[0288] The average particle size Dv50 of the negative electrode active material was adjusted to 20 μm, and the rest was the same as in Example 1.

[0289] Example 7-6

[0290] The average particle size Dv50 of the negative electrode active material was adjusted to 25 μm, and the rest was the same as in Example 1.

[0291] Example 7-7

[0292] The average particle size Dv50 of the negative electrode active material was adjusted to 28 μm, and the rest was the same as in Example 1.

[0293] Example 8-1

[0294] The coating weight per unit area (CW) of the negative electrode sheet was adjusted to 1.5 mg / cm 2 , the rest is the same as Example 1.

[0295] Example 8-2

[0296] The coating weight per unit area (CW) of the negative electrode sheet was adjusted to 3 mg / cm 2 , the rest is the same as Example 1.

[0297] Example 8-3

[0298] The coating weight per unit area (CW) of the negative electrode sheet is adjusted to 6 / cm 2 , the rest is the same as Example 1.

[0299] Example 8-4

[0300] The coating weight per unit area (CW) of the negative electrode sheet was adjusted to 12 mg / cm 2 , the rest is the same as Example 1.

[0301] Example 8-5

[0302] The coating weight per unit area (CW) of the negative electrode sheet was adjusted to 15 mg / cm 2 , the rest is the same as Example 1.

[0303] Comparative Example 1-1

[0304] The remainder of the process was the same as in Example 1 except that Compound 1 as the first additive was removed.

[0305] Comparative Example 1-2

[0306] The remainder of the process was the same as in Example 1 except that compound 12 as the second additive was removed.

[0307] Comparative Examples 1-3

[0308] Compound 8 was used instead of Compound 1 as the first additive, and the rest was the same as in Example 1.

[0309] Performance testing:

[0310] 1) 60℃ cycle performance test

[0311] At 60°C, the batteries of the above examples and comparative examples were charged at a constant current of 1C to a voltage of 3.65V. They were then charged at a constant voltage of 3.65V to a current of ≤0.05C. The batteries were then discharged at a constant current of 1C to a voltage of 2.5V. This constituted one charge and discharge cycle, and the discharge capacity at this point was recorded as the discharge capacity of the battery's first cycle. This charge and discharge cycle was repeated, and the capacity retention rate of the batteries after 500 cycles was calculated.

[0312] The capacity retention rate (%) of the battery after 500 cycles at 60° C. = (discharge capacity of the battery at the 500th cycle / discharge capacity of the battery at the first cycle)×100%.

[0313] 2) 60℃ storage capacity retention test

[0314] At 25°C, the batteries of the above embodiments and comparative examples were charged at a constant current of 0.33C to a voltage of 3.65V, and then charged at a constant voltage of 3.65V to a current ≤ 0.05C. The batteries were discharged at a constant current of 0.33C to a voltage of 2.5V, and the actual discharge capacity of the batteries was recorded as C0.

[0315] At 25°C, the battery was charged at a constant current of 0.33C0 to a voltage of 3.65V, and then charged at a constant voltage of 3.65V to a current of ≤0.05C0, at which point the battery was fully charged. The fully charged battery was stored in a constant temperature box at 60°C for 60 days, and then the battery was removed for capacity testing.

[0316] The capacity retention rate of the battery after storage at 60° C. for 60 days=(discharge capacity of the battery after storage for 60 days / actual discharge capacity C0 of the battery)×100%.

[0317] The results are recorded in Table 4.

[0318] Table 4

[0319] It can be seen from the results of Examples 1 and 2-1 to 2-6 and Comparative Examples 1-1 and 1-3 that the introduction of cyclic sulfate additives can effectively improve the cycle and storage performance of the battery cell at high temperatures. It also shows that compared with conventional sultone additives, the SEI generated by the additive at the negative electrode has lower interfacial impedance and higher stability at high temperatures.

[0320] Compared with Comparative Example 1-2, Examples 1 and 4-1 to 4-16 show that the introduction of the second additive can significantly improve the cycle storage performance of the battery cell at high temperature. This is because at high temperature, LiPF6 easily decomposes to produce HF, causing continuous damage to the SEI. By introducing alkyl phosphate or isocyanate additives, the acid content in the electrolyte is reduced, thereby extending the cycle storage life of the battery at high temperature.

[0321] The results of Examples 3-1 to 3-5 show that too little of the first additive does not significantly improve performance, while too much of it may form a thicker SEI at the negative electrode, increasing polarization and, to a certain extent, deteriorating the cycling and storage performance at high temperatures. When the mass percentage of the cyclic sulfonate additive in the electrolyte is within the preferred range, the battery cell exhibits better cycling and storage performance.

[0322] The results of Examples 5-1 to 5-7 show that too little of the second additive does not significantly improve performance, while too much of the second additive can worsen cycling and storage performance at high temperatures. When the mass percentage of the second additive in the electrolyte is within the preferred range, the battery cell exhibits better cycling and storage performance.

[0323] The results of Examples 6-1 to 6-5 show that when the porosity of the negative electrode material layer on the electrode sheet is too small, the particle structure of the negative electrode active material is squeezed and damaged, electrolyte infiltration becomes difficult, polarization increases, and the long-term cycle performance of the battery cell deteriorates. When the porosity ratio of the negative electrode active material coating of the present application is within the above preferred range, the battery cell can exhibit excellent performance at high temperatures.

[0324] The results of Examples 7-1 to 7-9 show that when the Dv50 of the negative electrode active material is too low, resulting in an excessively large specific surface area, the battery may have increased contact with the electrolyte, leading to more intense side reactions and accumulation of byproducts on the battery surface, increasing the negative electrode impedance and resulting in capacity loss during high-temperature cycling. When the Dv50 of the negative electrode active material is within the preferred range, the battery can achieve better performance.

[0325] The results of Examples 8-1 to 8-5 show that the lower the negative electrode coating weight per unit area, the better the battery's kinetic performance. However, to meet energy density requirements, a lower coating weight requires a larger coating area, increasing battery manufacturing costs. Excessive coating weight can hinder electrolyte transfer, thereby affecting the battery's cycle storage performance. Therefore, when the negative electrode coating weight per unit area falls within the preferred range, the battery's energy density and performance are not affected while maintaining good kinetics.

[0326] Although the present application has been described with reference to preferred embodiments, various modifications may be made thereto and components may be substituted with equivalents without departing from the scope of the present application. In particular, the various technical features described in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present application is not limited to the specific embodiments disclosed herein, but encompasses all technical solutions within the scope of the claims.

Claims

1. A non-aqueous electrolyte, comprising a first additive and a second additive, wherein the first additive is a cyclic sulfate ester compound having a structure represented by general formula (I), In the general formula (I), R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group, In the general formula (II), R 5 and R 6 Each is independently selected from any one of a group having a structure represented by the general formula (II), a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group and a sulfonic acid group; R 1 and R 2 are not hydrogen atoms and R 3 and R 4 Not all hydrogen atoms at the same time; The second additive is selected from a phosphate compound, an isocyanate compound or a combination thereof; The phosphate compound has a structure shown in the general formula (III): In the general formula (III), R 1 , R 2 , R 3 , R 4 , R 5 Each is independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C6 alkyl group, a halogen atom, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C6-C10 aryl group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, a hydroxyl group, a sulfonic acid group, and a tri(C1-C6 alkyl)silyl group; In the general formula (IV), R 6 , R 7 , R 8 Each is independently selected from any one of a hydrogen atom, a C1-C6 alkyl group, a halogen atom, a C1-C6 haloalkyl group, a C1-C6 alkoxy group, a C1-C6 haloalkoxy group, a C6-C10 aryl group, a C2-C6 alkenyl group, a C2-C6 ester group, a cyano group, and a sulfonic acid group; The isocyanate compound has a structure shown in general formula (V): In the general formula (V), R 1 is unsubstituted or substituted with one or more R a Substituted groups: C2-C10 alkylene, C2-C10 heteroalkylene, C6-C18 arylene, C2-C18 heteroarylene, C3-C18 alicyclic, C3-C18 hetero alicyclic, The one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C10 ester group, a C1-C10 alkyl group, a C2-C10 alkenyl group, a C2-C10 alkynyl group, and a C2-C10 alkoxy group; In the general formula (V), n is 1, 2 or 3.

2. The non-aqueous electrolyte according to claim 1, wherein in the cyclic sulfate ester compound, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group, In the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group and a sulfonic acid group; Optionally, in the cyclic sulfate compound, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a halogen atom, a C1-C3 alkyl group and a cyano group; Optionally, in the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom and a C1-C3 alkyl group; Optionally, in the cyclic sulfate compound, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by general formula (II), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group and a cyano group; Optionally, in the cyclic sulfate compound, R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a methyl group, an ethyl group, a propyl group and an isopropyl group; Optionally, the group of the structure represented by the general formula (II) is selected from any one of the following groups: in, X is a F atom, a Cl atom or a Br atom; Optionally, the group of the structure represented by the general formula (II) is selected from any one of the following groups: Optionally, the cyclic sulfate ester compound is selected from any one or more of the following compounds: 5 . The non-aqueous electrolyte according to claim 1 , wherein the mass content of the cyclic sulfate ester compound is W1, wherein 0.005%≤W1≤10%, optionally 0.05%≤W1≤5%.

6. The non-aqueous electrolyte according to any one of claims 1 to 5, wherein in the phosphate ester compound, R 1 , R 2 , R 3 , R 4 , R 5 Each is independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C6-C10 aryl group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group, a hydroxyl group, a sulfonic acid group, and a tri(C1-C3 alkyl)silyl group; In the general formula (IV), R 6 , R 7 , R 8 Each is independently selected from any one of a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C6-C10 aryl group, a C2-C3 alkenyl group, a C2-C3 ester group, a cyano group, and a sulfonic acid group; Optionally, in the phosphate compound, R 1 , R 2 , R 3 , R 4 , R 5 Each is independently selected from any one of a group having a structure represented by general formula (IV), a hydrogen atom, a C1-C3 alkyl group, a halogen atom, a C1-C3 alkoxy group, and a tri(C1-C3 alkyl)silyl group; Optionally, in the general formula (IV), R 6 , R 7 , R 8 Each is independently selected from any one of a hydrogen atom, a C1-C3 alkyl group, and a C1-C3 alkoxy group; Optionally, the group of the structure shown in general formula (IV) is selected from any one of the following groups: Optionally, the phosphate compound is selected from any one or more of the following compounds:

7. The non-aqueous electrolyte according to any one of claims 1 to 6, wherein in the isocyanate compound, R 1 is unsubstituted or substituted with one or more R a Substituted groups: C2-C6 alkylene, C2-C6 heteroalkylene, C6-C10 arylene, C2-C10 heteroarylene, C4-C6 alicyclic, C4-C6 hetero alicyclic, Optionally, the one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C6 ester group, a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, and a C2-C6 alkoxy group; Optionally, the one or more R a Each is independently selected from a halogen atom, -CN, -NCO, -OH, -COOH, -SOOH, a C2-C3 ester group, a C1-C3 alkyl group, a C2-C3 alkenyl group, a C2-C3 alkynyl group, and a C2-C3 alkoxy group; Optionally, in the isocyanate compound, R 1 is unsubstituted or substituted with one or more R a Substituted groups: C2-C6 alkylene, C6-C10 arylene, C4-C6 alicyclic, The one or more R a Each is independently selected from a halogen atom, a C1-C3 alkyl group; Optionally, the isocyanate compound is selected from any one or more of the following compounds:

8. The non-aqueous electrolyte according to any one of claims 1 to 7, wherein the mass proportion of the second additive in the non-aqueous electrolyte is W2, wherein 0.01%≤W2≤10%, optionally 0.1%≤W2≤8%, optionally 0.3%≤W2≤5%. 9 . A secondary battery comprising the nonaqueous electrolyte according to claim 1 , and further comprising a positive electrode sheet and a negative electrode sheet, wherein the negative electrode sheet comprises a negative electrode material layer containing a negative electrode active material. 10 . The secondary battery of claim 9 , wherein the porosity of the negative electrode material layer is 30% to 45%, and optionally 37% to 42%. 11 . The secondary battery according to claim 9 , wherein the average particle size Dv50 of the negative electrode active material is 3 to 25 μm, optionally 5 μm≤Dv50≤20 μm, optionally 7 μm≤Dv50≤15 μm.

12. The secondary battery according to any one of claims 9 to 11, wherein the coating weight per unit area of ​​the negative electrode sheet is CW, 2 mg / cm 2 ≤CW≤13mg / cm 2 , optionally, 5 mg / cm 2 ≤CW≤10mg / cm 2 .

13. An electrical device comprising a secondary battery, in, The secondary battery comprises the secondary battery according to any one of claims 9 to 12.

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