Non-aqueous electrolyte for secondary battery, secondary battery and electric device

Abstract

The invention provides a non-aqueous electrolyte for a secondary battery, the secondary battery and an electric device. The non-aqueous electrolyte for the secondary battery comprises an additive and a non-aqueous solvent, wherein the non-aqueous solvent comprises a first solvent; the additive comprises a cyclic sulfate compound as shown in a formula (I); the first solvent is selected from one or more of ethylene glycol dimethyl ether, a compound as shown in a formula A and a compound as shown in a formula B; # imgabs0 #

Description

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

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

[0002] In recent years, the application of secondary batteries has become increasingly widespread. They are widely used in energy storage systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, and other fields. As secondary batteries have achieved significant development, higher requirements have been placed on their fast-charging performance, cycle performance, and safety performance.

[0003] Summary of the Invention

[0004] This application is made in view of the above-mentioned problems, and its purpose is to provide a non-aqueous electrolyte for a secondary battery, a secondary battery, and an electrical device. The non-aqueous electrolyte of the present application improves the fast charging performance, cycle performance, and storage performance of the battery, and reduces the cycle gas production of the battery.

[0005] In order to achieve the above-mentioned object, the present application provides a non-aqueous electrolyte for a secondary battery in a first aspect, comprising an additive and a non-aqueous solvent, wherein the non-aqueous solvent comprises a first solvent;

[0006] The additive comprises a cyclic sulfate compound represented by formula (I),

[0007] Among them, R 1 、R 2 、R 3 and R 4 Each is independently selected from any one of a group having a structure represented by 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, and n1 and n2 are each independently any integer from 0 to 2,

[0008] R 5 and R 6 Each is independently selected from any one of 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, and n3 is any integer from 0 to 2;

[0009] R 1 and R 2are not hydrogen atoms and R 3 and R 4 Not all hydrogen atoms at the same time;

[0010] Or, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0011] 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 at the same time;

[0012] Or, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0013] 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 at the same time;

[0014] The first solvent is selected from one or more of ethylene glycol dimethyl ether, the compound represented by formula A, and the compound represented by formula B.

[0015] Among them, R 7 、R 8 and R 9 Each is independently selected from any one of C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy and C1-C6 haloalkoxy;

[0016] And, R 7 and R 8 It does not contain oxygen atoms at the same time.

[0017] Therefore, the present application forms a non-aqueous electrolyte by combining a first solvent and an additive; on the one hand, the first solvent can make the electrolyte have a lower viscosity, improve the conductivity of the electrolyte, and thereby improve the fast charging performance of the battery; on the other hand, during the battery charging process, the additive forms a more stable, more electron-blocking inorganic and organic mixed SEI film on the surface of the negative electrode, which inhibits the reaction between the first solvent and the negative electrode, thereby reducing the battery's cycle gas production, improving the cycle performance, and improving the storage performance.

[0018] In any embodiment, the cyclic sulfate compound has a structure represented by formula (I-1),

[0019] 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-1), 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;

[0020] R 5 and R 6 Each is independently selected from any one of 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.

[0021] The cyclic sulfate rings in the general formula (I-1) are all five-membered rings, which can form a denser SEI film. Compared to six-membered rings, they have greater ring tension and are easier to form at the negative electrode. However, six-membered rings have less ring tension and are more stable, but they form more slowly at the negative electrode. Therefore, the efficiency of forming the electron-blocking SEI film is lower, which affects the effectiveness of the SEI film.

[0022] In any embodiment, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a group having a structure represented by general formula (II-1), 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 and a cyano group; R 5 and R 6Each 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 and a cyano group;

[0023] Optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a group having a structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group and a cyano group; 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 and a cyano group;

[0024] More optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a group having a structure represented by general formula (II-1), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group; R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group;

[0025] Further optionally, the group of the structure represented by the general formula (II-1) is selected from any one of the following groups:

[0026] Wherein, X is a F atom, a Cl atom or a Br atom.

[0027] In any embodiment, R 1 、R 2 、R 3 and R 4 Each independently selected from Any one of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group, wherein X is a F atom;

[0028] Optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from Any one of a hydrogen atom, a F atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group, an ethoxy group and a cyano group, wherein X is a F atom.

[0029] In any embodiment, the cyclic sulfate compound is selected from the following compounds:

[0030] The preparation method of the cyclic sulfate compound is simple, which is conducive to promotion and implementation in industry, and has a more stable effect on improving the cycle performance of the battery.

[0031] In any embodiment, R 7 、R 8 and R 9 are each independently selected from any one of C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy and C1-C3 haloalkoxy; and R 7 and R 8 does not simultaneously contain oxygen atoms;

[0032] Optionally, R 7 、R 8 and R 9 Each is independently selected from any one of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy, fluoromethoxy, fluoroethoxy and fluoropropoxy.

[0033] In any embodiment, R 7 and R 8 Each independently selected from any one of C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy and C1-C6 haloalkoxy; R 9 Any one selected from C1-C6 alkyl and C1-C6 haloalkyl; and R 7 and R 8 It does not contain oxygen atoms at the same time.

[0034] In any embodiment, R 7 and R 8 Each is independently selected from any one of C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy and C1-C3 haloalkoxy; R 9 Any one selected from C1-C3 alkyl and C1-C3 haloalkyl; and R 7 and R 8 does not simultaneously contain oxygen atoms;

[0035] Optionally, R 7 and R 8Each is independently selected from any one of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy, fluoromethoxy, fluoroethoxy and fluoropropoxy; R 9 Any one selected from methyl, ethyl, propyl, fluoromethyl, fluoroethyl and fluoropropyl;

[0036] More optionally, R 7 and R 8 Each independently selected from any one of methyl, ethyl, monofluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, methoxy, ethoxy, difluoromethoxy and 2,2,2-trifluoroethoxy; R 9 Any one selected from methyl, ethyl, propyl and 2-fluoroethyl.

[0037] In any embodiment, the first solvent is selected from one or more of the following compounds:

[0038] The first solvent mentioned above makes the electrolyte have a lower viscosity and a higher dielectric constant, thereby making the electrolyte have a higher conductivity, improving the transmission rate of lithium ions in the electrolyte and the electrode, thereby improving the fast charging performance of the battery.

[0039] In any embodiment, the mass content of the additive in the non-aqueous electrolyte is 0.001%-15%, optionally 0.005%-10%, and more optionally 0.05%-5%.

[0040] When the mass content of the additive in the non-aqueous electrolyte is within the above range, the conductivity of the electrolyte can be further improved, thereby further improving the fast charging performance of the battery, enhancing the cycle performance and storage performance of the battery, and reducing the cycle gas production of the battery.

[0041] In any embodiment, the mass content of the first solvent in the non-aqueous solvent is 10%-90%, optionally 20%-80%, and more optionally 30%-70%.

[0042] The mass content of the first solvent in the non-aqueous solvent is within the above range, which can further improve the fast charging performance of the battery, improve the cycle performance and storage performance of the battery, and reduce the cycle gas production of the battery.

[0043] The second aspect of the present application further provides a secondary battery, comprising the non-aqueous electrolyte of the first aspect of the present application and a negative electrode plate, wherein the negative electrode plate comprises a negative electrode active material; optionally, the secondary battery is a lithium secondary battery.

[0044] Therefore, the present application forms a non-aqueous electrolyte by combining a first solvent and an additive; on the one hand, the first solvent can make the electrolyte have a lower viscosity, improve the conductivity of the electrolyte, and thereby improve the fast charging performance of the battery; on the other hand, during the battery charging process, the additive forms a more stable, more electron-blocking inorganic and organic mixed SEI film on the surface of the negative electrode, which inhibits the reaction between the first solvent and the negative electrode, thereby reducing the battery's cycle gas production, improving the cycle performance, and improving the storage performance.

[0045] In any embodiment, the porosity of the negative electrode plate is 15%-35%, optionally 18%-30.5%, and more optionally 20%-27%.

[0046] The porosity of the negative electrode sheet within the above range is beneficial to improving the energy density of the battery, while increasing the transmission rate of lithium ions in the negative electrode sheet, improving the fast charging performance and dynamic performance of the battery, increasing the cycle life of the battery, and reducing the cycle gas production of the battery.

[0047] In any embodiment, the volume average particle size Dv50 of the negative electrode active material is greater than or equal to 3 μm, optionally greater than or equal to 6 μm or 3-25 μm, and more optionally 15-20 μm.

[0048] The volume average particle size Dv50 of the negative electrode active material meets the above range, which is conducive to forming a stable SEI film on the negative electrode surface and reducing the side reaction between the electrolyte and the negative electrode active material, reducing the battery's cycle gas production, and improving the battery's cycle performance, storage performance and fast charging performance.

[0049] A third aspect of the present application provides an electrical device comprising the non-aqueous electrolyte of the first aspect of the present application or the secondary battery of the second aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0051] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .

[0052] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0053] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0054] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0055] 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.

[0056] Description of reference numerals:

[0057] 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

[0058] Below, the embodiments of the non-aqueous electrolyte for secondary batteries, secondary batteries, battery modules, battery packs and electrical devices 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 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.

[0059] " 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.

[0060] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0061] 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.

[0062] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, a method includes steps (a) and (b), which indicates 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 further include step (c), which indicates 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.

[0063] 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 indicate that other components not listed may also be included or that only the listed components are included.

[0064] 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).

[0065] If not otherwise specified, in this application, the term "halogen" refers to atoms of Group VIIA elements, including fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), etc.

[0066] Unless otherwise specified, in this application, the term "C1-C6 alkyl" refers to a straight-chain or branched alkyl group containing 1 to 6 carbon atoms, specifically including C1-C3 alkyl, C2-C4 alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl or n-hexyl, etc.

[0067] Unless otherwise specified, the term "C1-C6 haloalkyl" as used herein refers to a C1-C6 alkyl group with one or more H groups substituted with a halogen, wherein "C1-C6 alkyl" and "halogen" are as defined above. Specifically, it includes C1-C3 haloalkyl and C2-C4 haloalkyl groups, such as monofluoromethyl, difluoromethyl, trifluoromethyl, and 2,2,2-trifluoroethyl.

[0068] If not otherwise specified, in this application, the term "C1-C6 alkoxy" refers to a C1-C6 alkyl-O-group, wherein "C1-C6 alkyl" is as described above. Non-limiting examples of suitable C1-C6 alkoxy groups include methoxy, ethoxy, and isopropoxy.

[0069] Unless otherwise specified, the term "C1-C6 haloalkoxy" as used herein refers to a C1-C6 alkoxy group with one or more H groups substituted by a halogen, wherein "C1-C6 alkoxy" and "halogen" are as defined above. Specifically, it includes C1-C3 haloalkoxy and C2-C4 haloalkoxy groups, such as difluoromethoxy, trifluoromethoxy, and 2,2,2-trifluoroethoxy.

[0070] Unless otherwise specified, in this application, the term "C2-C6 alkenyl" refers to a straight-chain or branched monovalent hydrocarbon group containing 2 to 6 carbon atoms and having at least one unsaturated carbon-carbon double bond, specifically including C2-C5 alkenyl, C2-C4 alkenyl, such as ethylene, propylene, n-butene, isobutene, n-pentene, isopentene, etc.

[0071] Unless otherwise specified, in this application, the term "C2-C6 ester group" refers to -COO-C1-C6 alkyl, wherein "C1-C6 alkyl" is as described above. Specifically, it includes C2-C5 ester groups and C2-C4 ester groups, such as -COOCH3, -COOCH2CH3, etc.

[0072] [Secondary battery]

[0073] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be recharged to activate the active materials after discharge and continue to be used.

[0074] Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the battery's charge and discharge process, active ions (such as lithium ions) are embedded and released back and forth between the positive and negative electrode sheets. The separator is set between the positive and negative electrode sheets, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte between the positive and negative electrode sheets mainly plays the role of conducting active ions.

[0075] [Non-aqueous electrolyte for secondary batteries]

[0076] One embodiment of the present application provides a non-aqueous electrolyte for a secondary battery, comprising an additive and a non-aqueous solvent, wherein the non-aqueous solvent comprises a first solvent;

[0077] The additive comprises a cyclic sulfate compound represented by formula (I),

[0078] Among them, R 1 、R 2 、R 3 and R 4Each is independently selected from any one of a group having a structure represented by 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, n1 and n2 are each independently any integer from 0 to 2, for example, 0, 1 or 2,

[0079] R 5 and R 6 are each independently selected from any one of 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, and n3 is any integer from 0 to 2, for example, 0, 1 or 2;

[0080] R 1 and R 2 are not hydrogen atoms and R 3 and R 4 Not all hydrogen atoms at the same time;

[0081] Or, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0082] 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 at the same time;

[0083] Or, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0084] R 3 and R 4 At the same time, it is a hydrogen atom and R 1 and R 2One 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 at the same time;

[0085] The first solvent is selected from one or more of ethylene glycol dimethyl ether, the compound represented by formula A, and the compound represented by formula B.

[0086] Among them, R 7 、R 8 and R 9 Each is independently selected from any one of C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy and C1-C6 haloalkoxy;

[0087] And, R 7 and R 8 It does not contain oxygen atoms at the same time.

[0088] Although the mechanism is still unclear, the applicant unexpectedly discovered that the present application forms a non-aqueous electrolyte by combining a first solvent and an additive; on the one hand, the first solvent can make the electrolyte have a lower viscosity, improve the conductivity of the electrolyte, and thus improve the fast charging performance of the battery; on the other hand, during the battery charging process, the additive forms a more stable, more electron-blocking inorganic and organic mixed SEI film on the surface of the negative electrode, which inhibits the reaction between the first solvent and the negative electrode, thereby reducing the battery's cycle gas production, improving the cycle performance, and improving the storage performance.

[0089] In some embodiments, the cyclic sulfate compound has a structure shown in formula (I-1),

[0090] 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-1), 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;

[0091] R 5 and R 6Each is independently selected from any one of 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.

[0092] The cyclic sulfate rings in the general formula (I-1) are all five-membered rings, which can form a denser SEI film. Compared to six-membered rings, they have greater ring tension and are easier to form at the negative electrode. However, six-membered rings have less ring tension and are more stable, but they form more slowly at the negative electrode. Therefore, the efficiency of forming the electron-blocking SEI film is lower, which affects the effectiveness of the SEI film.

[0093] In some embodiments, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a group having a structure represented by general formula (II-1), 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 and a cyano group; 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 and a cyano group;

[0094] Optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a group having a structure represented by general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group and a cyano group; 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 and a cyano group;

[0095] More optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a group having a structure represented by general formula (II-1), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group; R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group;

[0096] Further optionally, the group of the structure represented by the general formula (II-1) is selected from any one of the following groups:

[0097] Wherein, X is a F atom, a Cl atom or a Br atom.

[0098] In some embodiments, R 1 、R 2 、R 3 and R 4 Each independently selected from Any one of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group, wherein X is a F atom;

[0099] Optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from Any one of a hydrogen atom, a F atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group, an ethoxy group and a cyano group, wherein X is a F atom.

[0100] In some embodiments, the cyclic sulfate compound is selected from the following compounds:

[0101] The preparation method of the cyclic sulfate compound is simple, which is conducive to promotion and implementation in industry, and has a more stable effect on improving the cycle performance of the battery.

[0102] The numbers of the above compounds are shown in the table below.

[0103] In some embodiments, the preparation method of the cyclic sulfate compound having the structure shown in general formula (I) is:

[0104] 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:

[0105] 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. 1 、R 2 、R 3 、R4 , n1, n2 are defined as described above.

[0106] In some embodiments, R 7 、R 8 and R 9 are each independently selected from any one of C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy and C1-C3 haloalkoxy; and R 7 and R 8 does not simultaneously contain oxygen atoms;

[0107] Optionally, R 7 、R 8 and R 9 Each is independently selected from any one of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy, fluoromethoxy, fluoroethoxy and fluoropropoxy.

[0108] In some embodiments, R 7 and R 8 Each independently selected from any one of C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy and C1-C6 haloalkoxy; R 9 Any one selected from C1-C6 alkyl and C1-C6 haloalkyl; and R 7 and R 8 It does not contain oxygen atoms at the same time.

[0109] In some embodiments, R 7 and R 8 Each is independently selected from any one of C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy and C1-C3 haloalkoxy; R 9 Any one selected from C1-C3 alkyl and C1-C3 haloalkyl; and R 7 and R 8 does not simultaneously contain oxygen atoms;

[0110] Optionally, R 7 and R 8 Each is independently selected from any one of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy, fluoromethoxy, fluoroethoxy and fluoropropoxy; R 9 Any one selected from methyl, ethyl, propyl, fluoromethyl, fluoroethyl and fluoropropyl;

[0111] More optionally, R 7 and R 8Each independently selected from any one of methyl, ethyl, monofluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, methoxy, ethoxy, difluoromethoxy and 2,2,2-trifluoroethoxy; R 9 Any one selected from methyl, ethyl, propyl and 2-fluoroethyl.

[0112] In some embodiments, the first solvent is selected from one or more of the following compounds:

[0113] The first solvent mentioned above makes the electrolyte have a lower viscosity and a higher dielectric constant, thereby making the electrolyte have a higher conductivity, improving the transmission rate of lithium ions in the electrolyte and the electrode, thereby improving the fast charging performance of the battery.

[0114] The numbers and CAS numbers of the above compounds are shown in the table below.

[0115] In some embodiments, the mass content of the additive in the non-aqueous electrolyte is 0.001%-15%, optionally 0.005%-10%, and more optionally 0.05%-5%, for example, 0.001%, 0.003%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 2%, 3%, 5%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 15% and the range consisting of any of the above values.

[0116] When the mass content of the additive in the non-aqueous electrolyte is within the above range, the conductivity of the electrolyte can be further improved, thereby further improving the fast charging performance of the battery, enhancing the cycle performance and storage performance of the battery, and reducing the cycle gas production of the battery.

[0117] In some embodiments, the mass content of the first solvent in the non-aqueous solvent is 10%-90%, optionally 20%-80%, and more optionally 30%-70%, for example, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and the range consisting of any of the above values.

[0118] The mass content of the first solvent in the non-aqueous solvent is within the above range, which can further improve the fast charging performance of the battery, improve the cycle performance and storage performance of the battery, and reduce the cycle gas production of the battery.

[0119] In some embodiments, the non-aqueous electrolyte includes an electrolyte salt.

[0120] In some embodiments, the electrolyte salt may be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalatoborate, lithium dioxalatoborate, lithium difluorodioxalatophosphate, and lithium tetrafluorooxalatophosphate.

[0121] In some embodiments, the non-aqueous electrolyte further includes other solvents, which can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0122] In some embodiments, the electrolyte may optionally include additives. For example, the additives may include positive electrode film-forming additives, and may also include additives that can improve certain battery properties, such as additives that improve battery overcharge performance, and additives that improve battery high or low temperature performance.

[0123] [Positive electrode]

[0124] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0125] As an 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 either or both of the two opposite surfaces of the positive electrode current collector.

[0126] 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.).

[0127] In some embodiments, the positive electrode active material may adopt the positive electrode active material for batteries that is well known in the art. 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. 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 0.05 O2) 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.

[0128] In some embodiments, the positive electrode film 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.

[0129] In some embodiments, the positive electrode film 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.

[0130] 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 current collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained.

[0131] [Negative electrode]

[0132] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material.

[0133] As an example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite 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 porosity of the negative electrode sheet is 15%-35%, optionally 18%-30.5%, and more optionally 20%-27%, for example, 15%, 17%, 18%, 19%, 20%, 22%, 24%, 25%, 27%, 30%, 31%, 33%, 35% and the range of any of the above values.

[0136] The porosity of the negative electrode sheet within the above range is beneficial to improving the energy density of the battery, while increasing the transmission rate of lithium ions in the negative electrode sheet, improving the fast charging performance and dynamic performance of the battery, increasing the cycle life of the battery, and reducing the cycle gas production of the battery.

[0137] In some embodiments, the porosity of the negative electrode sheet is tested using instruments and methods known in the art. For example, a small circular sample with a diameter of 14 mm is cut from a negative electrode sheet covered on one side with a negative electrode film; the thickness of the negative electrode film is measured (thickness of the negative electrode sheet minus thickness of the negative electrode current collector); the apparent volume V of the negative electrode film is calculated according to the cylinder volume calculation formula; the true volume of the negative electrode sheet is measured using a gas displacement method with inert helium as the medium using a true density tester (e.g., Micromeritics AccuPyc II 1340), with reference to GB / T 24586-2009; the true volume of the negative electrode sheet is subtracted from the volume of the negative electrode current collector to obtain the true volume V of the negative electrode sheet; the porosity of the negative electrode sheet is calculated according to the following formula. Multiple (e.g., 30) electrode sheet samples can be tested, and the results are averaged.

[0138] Porosity of the negative electrode sheet = 100% × (V meter of the negative electrode membrane - V true of the negative electrode membrane) / V meter of the negative electrode membrane.

[0139] In some embodiments, the volume average particle size Dv50 of the negative electrode active material is greater than or equal to 3 μm, and can be greater than or equal to 6 μm or 3-25 μm, and can be more preferably 15-20 μm, for example, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 12 μm, 13 μm, 15 μm, 17 μm, 18 μm, 20 μm, 21 μm, 22 μm, 23 μm, 25 μm and the range consisting of any of the above values.

[0140] The volume average particle size Dv50 of the negative electrode active material meets the above range, which is conducive to forming a stable SEI film on the negative electrode surface and reducing the side reaction between the electrolyte and the negative electrode active material, reducing the battery's cycle gas production, and improving the battery's cycle performance, storage performance and fast charging performance.

[0141] The volume average particle size Dv50 represents the particle size corresponding to the cumulative volume distribution percentage of the negative electrode active material reaching 50%. In some embodiments, the volume average particle size Dv50 is measured using instruments and methods known in the art. For example, it can be measured using a laser particle size analyzer (e.g., Master Size 300) in accordance with the particle size distribution laser diffraction method specified in GB / T 19077-2016.

[0142] In some embodiments, the negative electrode active material may be a negative electrode active material for a battery that is well known in the art. As an example, the negative electrode active material may include at least one of the following materials: artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may be selected from at least one of elemental silicon, silicon oxides, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. The tin-based material may 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 may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0143] In some embodiments, the negative electrode film 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).

[0144] In some embodiments, the negative electrode film 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.

[0145] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0146] 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.

[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 FIG2 , 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 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 electrical 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 electrical device, or as an energy storage unit for the electrical device. The electrical 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 an 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] Preparation Example 1: Compound 1-1 Synthesis

[0167] Step 1: Add 300g (2mol) of solid 1,6-dideoxygalactitol to a 2L 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 an intermediate product.

[0168] Step 2: To a 3L three-necked flask, 184.2g (0.8mol) of intermediate 1 was added, 1000mL of acetonitrile was added, 80mg 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 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, 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 acetonitrile was crystallized to obtain a white powder solid, which was the above-mentioned compound 1-1.

[0169] 1H-NMR, CD3CN, δppm 5.42-5.39(m,2H), 5.36-5.34(m,2H), 1.67-1.65(d,6H).

[0170] Preparation Example 2: Compound 1-2 Synthesis

[0171] Step 1: 356.5 g (2 mol) of solid 3,4,5,6-octanetrol was added to a 2 L three-necked flask, stirring was started, and 523 g (4.4 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 slurried and washed with deionized water several times until the pH was neutral. The filter cake was dried under reduced pressure at 60 ° C to obtain an intermediate product.

[0172] Step 2: 216.2 g (0.8 mol) of intermediate 1 was added to a 3L three-necked flask, 1000 mL of acetonitrile was added, and 80 mg of ruthenium trichloride trihydrate catalyst was added. 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, 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 1-2.

[0173] Preparation Example 3: Compound 1-3 Synthesis

[0174] Step 1: 328.4 g (2 mol) of solid 2,3,4,5-heptetrol was added to a 2L three-necked flask, stirring was started, and 523 g (4.4 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 slurried and washed with deionized water several times until the pH was neutral. The filter cake was dried under reduced pressure at 60°C to obtain an intermediate product.

[0175] Step 2: 205g (0.8mol) of intermediate product 1 was added to a 23-necked flask, 1000mL of acetonitrile was added, and the mixture was stirred until the solid was completely dissolved. 80mg of ruthenium trichloride trihydrate catalyst was added. After nitrogen replacement 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. 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 paper did not turn blue; the mixture was separated again, the organic layer was concentrated, and the acetonitrile crystallized to give compound 1-3 (163.1g, yield 82.8%).

[0176] Preparation Example 4: Compound 1-9 Synthesis

[0177] use (CAS No.: 7460-93-7) was used to replace 1,6-dideoxygalactitol, and the rest was the same as in Preparation Example 1. Compound LC-MS: 285.25.

[0178] Preparation Example 5: Compound 1-11 Synthesis

[0179] Step 1: 392.4 g (2 mol) of solid 1,2,3,4,5.6-heptanhexaol was added to a 2 L three-necked flask, stirring was started, and 784.5 g (6.6 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 slurried and washed with deionized water several times until the pH was neutral. The filter cake was dried under reduced pressure at 60 ° C to obtain an intermediate product.

[0180] Step 2: To a 4L three-necked flask, 140g (0.4mol) of intermediate 1 was added, 1000mL of acetonitrile was added, 110mg 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 1500g 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, 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 acetonitrile was crystallized to obtain compound 1-11.

[0181] Preparation Example 6: Compound 1-14 Synthesis

[0182] Step 1: 484 g (2 mol) of solid octitol was added to a 2L 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 an intermediate product.

[0183] Step 2: 183.2 g (0.4 mol) of the intermediate product 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 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 paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 1-14.

[0184] The preparation methods of compounds 1-4 to 1-8, compound 1-10, and compounds 1-12 to 1-13 can refer to the preparation examples and the preparation methods of the compounds of the general formula.

[0185] Example 1

[0186] (1) Preparation of an electrolyte: In an argon atmosphere glove box (H2O <0.1ppm, O2 <0.1ppm), the organic solvents ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed uniformly in a volume ratio of 3 / 7. Methyl acetate (Compound 2-3) was added as a first solvent, and the amount of methyl acetate added was adjusted to 60% by mass in the solvent. Then, 2% (by mass in the electrolyte) of the additive compound 1-1 and 12.5% ​​(by mass in the electrolyte) of LiPF6 were added and dissolved in the solvent, and stirred uniformly to obtain an electrolyte.

[0187] (2) Preparation of negative electrode sheets: The negative electrode active material graphite, the conductive agent carbon black, the binder styrene-butadiene rubber (SBR), and the thickener sodium carboxymethyl cellulose (CMC-Na) are dissolved in a solvent 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 sheets are obtained after drying, cold pressing under different pressures, and slitting.

[0188] (3) Preparation of positive electrode sheets: 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 the mixture is fully stirred and mixed to obtain a 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 a positive electrode sheet.

[0189] (4) Isolation film: Conventional polypropylene film is used as the isolation film.

[0190] (5) Secondary battery assembly: 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 layer, and then wound to obtain an electrode assembly; the electrode assembly is placed in a battery case, dried, and then injected with electrolyte, and then subjected to formation, standing, and other processes to obtain a secondary battery.

[0191] The secondary battery preparation methods of Examples 2-49 and Comparative Examples 1-2 are similar to those of Example 1, and the different product parameters are detailed in Table 2. The porosity of the negative electrode sheet is adjusted by the cold pressing pressure.

[0192] Table 2: Parameter results of Examples 1-49 and Comparative Examples 1-2

[0193] Material testing and battery testing

[0194] (1) Test of the porosity of the negative electrode:

[0195] Cut a small circular sample with a diameter of 14 mm from the negative electrode sheet covered on one side with a negative electrode film. Measure the thickness of the negative electrode film (negative electrode film thickness minus negative electrode current collector thickness). Calculate the apparent volume (V) of the negative electrode film using the cylindrical volume calculation formula. Measure the true volume of the negative electrode film using the gas displacement method with inert helium as the medium using a true density tester (Micromeritics AccuPyc II 1340), according to GB / T 24586-2009. Subtract the volume of the negative electrode current collector from the true volume of the negative electrode film to obtain the true volume (V) of the negative electrode film. Calculate the porosity of the negative electrode film using the following formula. 30 samples can be tested and the results averaged. Porosity of the negative electrode film = 100% × (V of the negative electrode film - V of the negative electrode film) / V of the negative electrode film.

[0196] (2) Test of volume average particle size Dv50:

[0197] The particle size distribution was determined by laser diffraction method according to GB / T 19077-2016 using a laser particle size analyzer Master Size 300.

[0198] (3) Fast charging performance test:

[0199] The capacity of the secondary battery is calibrated by charging and discharging with a 1 / 3C current, and a threshold value of 3.65V of the first charge cut-off voltage is determined according to the capacity calibration.

[0200] At 25°C, the secondary battery is first charged to 10% SOC at 0.1C, and then the secondary battery is charged with currents of 3C, 2.5C, 2C, 1.5C, 1C, and 0.5C in sequence; during the above charging process, the first charging cut-off voltage and the second lithium plating warning voltage of the secondary battery are obtained in real time. When the first charging cut-off voltage is greater than 3.65V or the second lithium plating warning voltage is less than or equal to -0.5mV, the current current is stopped, and the next current is used to continue charging in the above order until the secondary battery reaches 80% SOC and the charging is terminated; the cumulative time for the secondary battery to be charged from 10% SOC to 80% SOC is used as the charging time.

[0201] (4) Cyclic performance test:

[0202] At 25°C, the secondary battery is first fully discharged at 1C and then tested. The test process is: at 60°C, the secondary battery is charged at a constant current of 0.5C to a voltage of 3.65V, then charged at a constant voltage of 3.65V to a current of 0.05C. After standing for 5 minutes, the secondary battery is discharged at a constant current of 0.5C to a voltage of 2.5V. This is a charge and discharge cycle process, and the discharge capacity this time is the discharge capacity of the first cycle. The secondary battery is subjected to multiple cycle charge and discharge tests at 60°C according to the above method. The battery cycle capacity retention rate is calculated according to the following formula until the cycle capacity retention rate decays to 80%, and the number of cycles of the secondary battery is recorded. Cycle capacity retention rate (%) = (discharge capacity of the Nth cycle / discharge capacity of the first cycle) × 100%.

[0203] (5) Storage performance test:

[0204] At a constant temperature of 25°C, the secondary battery was charged at 0.33C to 3.65V, then discharged at 0.33C to 2.5V, to test the discharge capacity D1. The secondary battery was then stored at a constant temperature of 60°C and removed for testing every 30 days. During each test, the secondary battery was cooled to 25°C and charged at 0.33C to 3.65V, then discharged at 0.33C to 2.5V, to test the discharge capacity. The storage days and discharge capacity for each test were recorded, and a graph was plotted with storage days on the X-axis and discharge capacity on the Y-axis. The storage days required for the discharge capacity to decay to 90% of D1 were obtained.

[0205] (6) Volume expansion rate test:

[0206] At 25°C, first charge the secondary battery to 3.65V at a constant current of 0.33C, then charge it to a current of 0.05C at a constant voltage of 3.65V, and then discharge it to 2.5V at a constant current of 0.33C. The discharge capacity is the discharge capacity of the secondary battery before high-temperature storage; then charge the secondary battery to 3.65V at a constant current of 0.33C, and charge it to a current of 0.05C at a constant voltage of 3.65V. The secondary battery is fully charged and the volume of the secondary battery is tested by the drainage method. The secondary battery is then stored at 60°C for 60 days. After the storage is completed, the secondary battery is placed in a 25°C environment and the volume of the secondary battery is tested by the drainage method. The volume expansion rate of the secondary battery is calculated according to the following formula. Secondary battery volume expansion rate = 100% × (volume after storage - volume before storage) / volume before storage.

[0207] The results of items (1) to (2) above are shown in Table 2, and the results of items (3) to (6) are shown in Table 3. Table 3: Performance test results of Examples 1-49 and Comparative Examples 1-2

[0208] According to the above results, we can know that:

[0209] Compared to Comparative Example 1, the batteries of Examples 1-10 of the present application exhibited higher cycle performance and lower cycle gas production. Compared to Comparative Example 2, the batteries of Examples 11-13 of the present application exhibited higher cycle performance, higher storage performance, and lower cycle gas production. This demonstrates that batteries employing the non-aqueous electrolyte of the present application exhibit improved cycle and storage performance, while reducing cycle gas production.

[0210] Compared with Example 42, the batteries of Examples 1, 34-35 of the present application have higher cycle performance and storage performance and lower cycle gas production. Compared with Example 43, the batteries of Examples 1, 34-35 of the present application have higher fast charging performance.

[0211] Compared with Example 44, the fast charging performance of the batteries of Examples 1, 36-37 of the present application is higher. Compared with Example 45, the cycle performance and storage performance of the batteries of Examples 1, 36-37 of the present application are higher, and the cycle gas production is lower.

[0212] Compared with Example 46, the batteries of Examples 1, 38-39 of the present application have higher fast charging performance and cycle performance, and lower cycle gas production. Compared with Example 47, the batteries of Examples 1, 38-39 of the present application have higher fast charging performance, cycle performance, and storage performance, and lower cycle gas production.

[0213] Compared with Example 48, the batteries of Examples 1, 40-41 of the present application have higher cycle performance and storage performance, and lower cycle gas production. Compared with Example 49, the batteries of Examples 1, 40-41 of the present application have higher fast charging performance, cycle performance, and storage performance, and lower cycle gas production.

[0214] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A non-aqueous electrolyte for a secondary battery, comprising an additive and a non-aqueous solvent, wherein the non-aqueous solvent comprises a first solvent; The additive comprises a cyclic sulfate compound represented by formula (I), in, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by 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, and n1 and n2 are each independently any integer of 0-2, R 5 and R 6 Each is independently selected from any one of 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, and n3 is any integer from 0 to 2; R 1 and R 2 are not hydrogen atoms and R 3 and R 4 Not all hydrogen atoms at the same time; Or, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 The following conditions are met: R 1 and R 2 At the same time, R 3 and R 4 One is a hydrogen atom and the other is any one of a group having a structure represented by the 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 at the same time; Or, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 The following conditions are met: R 3 and R 4 At the same time, R 1 and R 2 One is a hydrogen atom and the other is any one of a group having a structure represented by the 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 at the same time; The first solvent is selected from one or more of ethylene glycol dimethyl ether, the compound represented by formula A and the compound represented by formula B, Among them, R 7 , R 8 and R 9 Each is independently selected from any one of C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy and C1-C6 haloalkoxy; And, R 7 and R 8 It does not contain oxygen atoms at the same time.

2. The nonaqueous electrolyte for secondary battery according to claim 1, in, The cyclic sulfate compound has a structure shown in formula (I-1), R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by the general formula (II-1), 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 5 and R 6 Each is independently selected from any one of 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.

3. The non-aqueous electrolyte for secondary battery according to claim 2, in, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by the general formula (II-1), 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 and a cyano group; 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 and a cyano group; Optionally, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by the general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group and a cyano group; 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 and a cyano group; More optionally, R 1 , R 2 , R 3 and R 4 Each is independently selected from any one of a group having a structure represented by the general formula (II-1), a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group; R 5 and R 6 Each is independently selected from any one of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group; Further optionally, the group of the structure represented by the general formula (II-1) is selected from any one of the following groups: Wherein, X is a F atom, a Cl atom or a Br atom.

4. The nonaqueous electrolyte for a secondary battery according to any one of claims 1 to 3, in, R 1 , R 2 , R 3 and R 4 Each independently selected from Any one of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a trifluoromethyl group, an ethoxy group and a cyano group, and X is a F atom; Optionally, R 1 , R 2 , R 3 and R 4 Each independently selected from Any one of a hydrogen atom, a F atom, a methyl group, an ethyl group, a propyl group, a trifluoromethyl group, an ethoxy group and a cyano group, wherein X is a F atom.

5. The nonaqueous electrolyte for secondary batteries according to any one of claims 1 to 4, in, The cyclic sulfate compound is selected from the following compounds:

6. The non-aqueous electrolyte for a secondary battery according to any one of claims 1 to 5, in, R 7 , R 8 and R 9 are each independently selected from any one of C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy and C1-C3 haloalkoxy; and R 7 and R 8 does not simultaneously contain oxygen atoms; Optionally, R 7 , R 8 and R 9 Each is independently selected from any one of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy, fluoromethoxy, fluoroethoxy and fluoropropoxy.

7. The nonaqueous electrolyte for a secondary battery according to any one of claims 1 to 6, in, R 7 and R 8 Each is independently selected from any one of C1-C6 alkyl, C1-C6 haloalkyl, C1-C6 alkoxy and C1-C6 haloalkoxy; R 9 is selected from any one of C1-C6 alkyl and C1-C6 haloalkyl; and R 7 and R 8 It does not contain oxygen atoms at the same time.

8. The nonaqueous electrolyte for a secondary battery according to any one of claims 1 to 7, in, R 7 and R 8 Each is independently selected from any one of C1-C3 alkyl, C1-C3 haloalkyl, C1-C3 alkoxy and C1-C3 haloalkoxy; R 9 is selected from any one of C1-C3 alkyl and C1-C3 haloalkyl; and R 7 and R 8 does not simultaneously contain oxygen atoms; Optionally, R 7 and R 8 Each is independently selected from any one of methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy, fluoromethoxy, fluoroethoxy and fluoropropoxy; R 9 Any one selected from methyl, ethyl, propyl, fluoromethyl, fluoroethyl and fluoropropyl; More optionally, R 7 and R 8 Each is independently selected from any one of methyl, ethyl, monofluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, methoxy, ethoxy, difluoromethoxy and 2,2,2-trifluoroethoxy; R 9 Any one selected from the group consisting of methyl, ethyl, propyl and 2-fluoroethyl.

9. The nonaqueous electrolyte for a secondary battery according to any one of claims 1 to 8, in, The first solvent is selected from one or more of the following compounds:

10. The nonaqueous electrolyte for a secondary battery according to any one of claims 1 to 9, in, The mass content of the additive in the non-aqueous electrolyte is 0.001%-15%, optionally 0.005%-10%, and more optionally 0.05%-5%.

11. The nonaqueous electrolyte for a secondary battery according to any one of claims 1 to 10, in, The mass content of the first solvent in the non-aqueous solvent is 10%-90%, optionally 20%-80%, and more optionally 30%-70%. 12 . A secondary battery, comprising the non-aqueous electrolyte for a secondary battery according to claim 1 and a negative electrode plate, wherein the negative electrode plate comprises a negative electrode active material; optionally, the secondary battery is a lithium secondary battery.

13. The secondary battery according to claim 12, in, The porosity of the negative electrode plate is 15%-35%, optionally 18%-30.5%, and more optionally 20%-27%.

14. The secondary battery according to claim 12 or 13, in, The volume average particle size Dv50 of the negative electrode active material is greater than or equal to 3 μm, and may be greater than or equal to 6 μm or 3-25 μm, and may be 15-20 μm. 15 . An electrical device comprising the nonaqueous electrolyte for a secondary battery according to claim 1 or the secondary battery according to claim 12 .

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