Non-aqueous electrolyte, secondary battery and electric device

Abstract

The invention provides a non-aqueous electrolyte, a secondary battery and an electric device. The non-aqueous electrolyte comprises an additive, the additive comprises a cyclic sulfate compound with a structure as shown in a general formula (I), R1, R2, R3, R4, R5 and R6 are respectively and independently selected from any one of a group with a structure as shown in a general formula (II), a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 halogenated alkyl, C1-C6 alkoxy, C1-C6 halogenated alkoxy, C2-C6 alkenyl, C2-C6 ester group, cyano and sulfonic acid group, and R1, R2, R3, R4, R5 and R6 are respectively and independently selected from any one of a group with a structure as shown in a general formula (II), a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 halogenated alkyl, C1-C6 alkoxy, C1-C6 halogenated alkoxy, C2-C6 alkenyl, C2-C6 ester group, a cyano group and a sulfonic acid group. And n1, n2 and n3 are respectively and independently any integer from 0 to 2. # imgabs0 #

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] In recent years, with the development of lithium-ion secondary battery technology, lithium-ion secondary batteries have been widely used in energy storage power 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 lithium-ion secondary batteries have achieved such rapid development, higher requirements have been placed on their fast charging performance, cycle performance, and safety performance.

[0003] Battery performance, especially for lithium secondary batteries used in automobiles, requires long life. Known reasons for the deterioration of battery life include the continued reduction of the electrolyte at the negative electrode during charging. To overcome these problems, attempts have been made to add various compounds to the electrolyte to form a passivation layer on the negative electrode surface, also known as the SEI film. This SEI film is a good lithium ion conductor and a poor electron conductor, inhibiting the continuation of lithium-consuming reactions and thus protecting the electrode. Studies have shown that the formation of a uniform, dense, stable, low-impedance, and well-adhesive solid electrolyte interphase (SEI) film is beneficial for improving the electrochemical performance of batteries.

[0004] Summary of the Invention

[0005] The present application provides a non-aqueous electrolyte, a secondary battery, and an electrical device to improve the cycle performance of the secondary battery.

[0006] The first aspect of the present application provides a non-aqueous electrolyte, comprising an additive, wherein the additive comprises a cyclic sulfate compound having a structure represented by general 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 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, and n1 and n2 are each independently any integer from 0 to 2;

[0008] General formula (II) is R 5 and R 6Each 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, and n3 is any integer from 0 to 2;

[0009] R 1 and R 2 are 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.

[0014] The cyclic sulfate compound of general formula (I), when used as an additive in a non-aqueous electrolyte, forms a more stable, electron-blocking hybrid inorganic and organic SEI film on the negative electrode side during the initial charge of a secondary battery. This SEI film blocks electrons, preventing the electrolyte from continuously decomposing at the negative electrode. This significantly improves the cycling performance of the battery cell while maintaining low resistance at the negative electrode, thereby significantly extending battery life.

[0015] In any embodiment of the first aspect, the cyclic sulfate compound has a structure represented by general formula (I-1),

[0016] 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-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;

[0017] General formula (II-1) is R 5 and R 6 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.

[0018] 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 positive and negative electrodes. 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.

[0019] In any embodiment of the first aspect, optionally, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 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-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C1-C3 ester group, a cyano group and a sulfonic acid group.

[0020] In any embodiment of the first aspect, optionally, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 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-C3 alkyl group, and a C1-C3 haloalkyl group.

[0021] In any embodiment of the first aspect, optionally, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 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 and an isopropyl group.

[0022] In any embodiment of the first aspect, optionally, the group of the structure represented by 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.

[0023] In any embodiment of the first aspect, optionally, 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 and a propyl group, wherein X is a F atom.

[0024] In any embodiment of the first aspect, optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a hydrogen atom, a methyl group and an ethyl group, and X is a F atom.

[0025] In any embodiment of the first aspect, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0026] The preparation method of the cyclic sulfate compound is simpler, easier to promote and implement in industry, and has a more stable effect on improving the cycle performance of secondary batteries.

[0027] In any embodiment of the first aspect, the mass content of the cyclic sulfate compound in the above-mentioned non-aqueous electrolyte is 0.001%-20%, for example, it can be 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, optionally 0.1%-10%, further optionally 0.1%-5%, so as to utilize the cyclic sulfate compound to form a sufficient organic and inorganic mixed SEI film with more stability and stronger electron blocking ability, which can not only effectively improve the cycle performance of the secondary battery, but also improve the output power of the secondary battery.

[0028] In any embodiment of the first aspect, the non-aqueous electrolyte further comprises an electrolyte, optionally comprising an alkali metal salt electrolyte; optionally comprising a lithium salt or a sodium salt; optionally, the lithium salt comprises one or more selected from the group consisting of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI); and the sodium salt comprises one or more selected from the group consisting of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium perchlorate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, and sodium trifluoromethanesulfonate. Each of the above lithium salts may be used alone or in combination of two or more.

[0029] In any embodiment of the first aspect, the non-aqueous electrolyte further comprises a non-aqueous solvent, and the non-aqueous solvent comprises any one or more of the group consisting of cyclic carbonate, chain carbonate, nitrile solvent, ketone solvent and sulfone solvent. Optionally, the non-aqueous solvent comprises 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. One or more of the above-mentioned non-aqueous solvents can be used alone or in combination of two or more.

[0030] In any embodiment of the first aspect, the additive further comprises one or more sultone compounds to further improve the battery's cycling performance. A second aspect of the present application provides a secondary battery comprising a positive electrode sheet, an electrolyte, a separator, and a negative electrode sheet, wherein the electrolyte is any of the non-aqueous electrolytes described above. The output power and lifespan of the secondary battery containing the non-aqueous electrolyte of the present application are significantly improved.

[0031] In a third aspect of the present application, an electrical device is provided, comprising a secondary battery, wherein the secondary battery comprises any one of the secondary batteries described above. The electrical device comprising the secondary battery of the present application has a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] 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.

[0033] FIG1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0034] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. 1 .

[0035] FIG3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0036] FIG4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0037] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application.

[0038] 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.

[0039] In the drawings, the drawings are not drawn to scale.

[0040] 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

[0041] 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.

[0042] 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.

[0043] " 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.

[0044] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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).

[0049] [Secondary battery]

[0050] 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.

[0051] Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charge and discharge process of the battery, active ions (such as lithium ions or sodium ions) are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing active ions to pass through. The electrolyte between the positive electrode sheet and the negative electrode sheet mainly plays the role of conducting active ions.

[0052] [Non-aqueous electrolyte]

[0053] One embodiment of the present application provides a non-aqueous electrolyte, comprising an additive, wherein the additive comprises a cyclic sulfate compound having a structure represented by general formula (I),

[0054] 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 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, and n1 and n2 are each independently any integer from 0 to 2;

[0055] General formula (II) is R 5 and R 6 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, and n3 is any integer from 0 to 2,

[0056] R 1 and R 2 are not hydrogen atoms and R3 and R 4 Not all hydrogen atoms at the same time;

[0057] Or, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0058] 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;

[0059] Or, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 The following conditions are met:

[0060] 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.

[0061] The cyclic sulfate compound of general formula (I), when used as an additive in a non-aqueous electrolyte, forms a more stable, electron-blocking hybrid inorganic and organic SEI film on the negative electrode side during the initial charge of a secondary battery. This SEI film blocks electrons, preventing the electrolyte from continuously decomposing at the negative electrode. This significantly improves the cycling performance of the battery cell while maintaining low resistance at the negative electrode, thereby significantly extending battery life.

[0062] The mechanism by which the above-mentioned cyclic sulfate compounds achieve the above-mentioned effects is still unclear, but the applicant speculates that, based on the skeleton of the cyclic sulfate compound having two cyclic sulfate rings connected, 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; by introducing substituents such as F and N, it 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 thereby improve the stability of the negative electrode SEI film, thereby achieving the purpose of improving the battery cycle performance.

[0063] 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.

[0064] In some embodiments of the present application, the cyclic sulfate compound has a structure represented by the general formula (I-1):

[0065] 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-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;

[0066] General formula (II-1) is R 5 and R 6Each 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.

[0067] 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 positive and negative electrodes. 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.

[0068] In some embodiments of the present application, optionally, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 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-C3 alkyl group, a C1-C3 haloalkyl group, a C1-C3 alkoxy group, a C1-C3 haloalkoxy group, a C2-C3 alkenyl group, a C1-C3 ester group, a cyano group and a sulfonic acid group.

[0069] In some embodiments of the present application, optionally, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 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-C3 alkyl group, and a C1-C3 haloalkyl group.

[0070] In some embodiments of the present application, optionally, R 1 、R 2 、R 3 、R 4 、R 5 and R 6 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 and an isopropyl group.

[0071] In some embodiments of the present application, optionally, the group represented by the structure of 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.

[0072] In some embodiments of the present application, optionally, 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 and an isopropyl group, wherein X is a F atom.

[0073] In some embodiments of the present application, optionally, R 1 、R 2 、R 3 and R 4 Each independently selected from any one of a hydrogen atom, a methyl group and an ethyl group, and X is a F atom.

[0074] In some embodiments of the present application, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0075] The preparation methods of the aforementioned cyclic sulfate ester compounds are simpler, easier to promote and implement in industry, and have a more stable effect on improving the life of secondary batteries.

[0076] The amount of the cyclic sulfate compound in each of the above embodiments of the present application can refer to the amount of conventional cyclic sulfate compounds in conventional non-aqueous electrolytes. In some embodiments, the mass content of the cyclic sulfate compound in the above non-aqueous electrolyte is 0.001%-20%, such as 0.001%, 0.005%, 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 15%, 20%, optionally 0.1%-10%, and further optionally 0.1%-5%. By utilizing the cyclic sulfate compound to form a sufficient organic and inorganic hybrid SEI film with a more stable and stronger electron-blocking ability, not only the cycle performance of the secondary battery can be effectively improved, but also the output power of the secondary battery can be improved. By limiting the above-mentioned mass content, it is possible to avoid the SEI film not being able to fully function due to too little content of the cyclic sulfate compound, and to avoid the electrolyte viscosity being too high and the SEI film formed on the negative electrode being too thick due to too much cyclic sulfate compound, thereby worsening the conductivity of the electrolyte and further worsening the improvement effect of the cycle performance and charging capacity.

[0077] In some embodiments, the non-aqueous electrolyte further includes an electrolyte. Any electrolyte that can be generally used in non-aqueous electrolytes can be considered for application in the non-aqueous electrolyte of the present application. Those skilled in the art can make a selection based on the battery system to which the non-aqueous electrolyte is applied, such as selecting a conventional electrolyte suitable for lithium-ion secondary batteries or sodium-ion secondary batteries. In some embodiments, the electrolyte in the above-mentioned non-aqueous electrolyte includes an alkali metal salt electrolyte; optionally, the electrolyte includes a lithium salt or a sodium salt; optionally, the lithium salt includes one or more selected from the group consisting of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and the sodium salt includes one or more selected from the group consisting of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium perchlorate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, and sodium trifluoromethanesulfonate. Each of the above-mentioned lithium salts or sodium salts can be used alone or in combination of two or more.

[0078] 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 0.1mol / L-5mol / L, for example, it can be 0.1mol / L, 0.3mol / L, 0.5mol / L, 1mol / L, 1.5mol / L, 2mol / L, 2.5mol / L, 3mol / L, 4mol / L or 5mol / L, optionally 0.5mol / L-1.5mol / L, further optionally 0.7mol / L-1.2mol / L.

[0079] The non-aqueous solvent of the present application can be selected from conventional non-aqueous solvents for secondary batteries. In some embodiments, the non-aqueous solvent includes any one or more of the group consisting of cyclic carbonates, chain carbonates, nitrile solvents, ketone solvents and sulfone solvents. Optionally, the non-aqueous solvent includes 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, to improve the load characteristics and low-temperature characteristics of a secondary battery, a mixed solvent of a cyclic carbonate and a chain carbonate can be used. When the non-aqueous electrolyte of the present application is used in a solid battery, a solid solvent such as dimethyl sulfone can be used.

[0080] In addition to the aforementioned additives, the additives may also include negative electrode film-forming additives, positive electrode film-forming additives, and 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. In some embodiments, the aforementioned additives also include one or more sultone compounds. By adding sultone compounds, the cycle performance of the secondary battery is further improved.

[0081] [Method for preparing a cyclic sulfate compound having a structure represented by general formula (I)]

[0082] 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:

[0083] 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.

[0084] [Positive electrode]

[0085] 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.

[0086] 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.

[0087] 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.).

[0088] In some embodiments, the positive electrode active material may be a positive electrode active material for a battery known in the art. As an example, the positive electrode active material for a lithium ion secondary battery may include at least one of the following materials: lithium-containing phosphates having an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of the lithium transition metal oxide 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 (which may also be abbreviated as NCM 333 ). Examples of the lithium-containing phosphates having an olivine structure may include, but are not limited to, lithium iron phosphate (such as LiFePO4 (which may also be abbreviated 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 manganese iron phosphate, and at least one of a composite material of lithium manganese iron phosphate and carbon.

[0089] As an example, the positive electrode active material for a sodium ion secondary battery may include at least one of the following materials: at least one of sodium transition metal oxides, polyanion-type compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventional materials that can be used as the positive electrode active material of the battery may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, in the sodium transition metal oxide, the transition metal includes at least one selected from the group consisting of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The sodium transition metal oxide is, for example, NaxMO2, where M includes one or several selected from the group consisting of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≤ 1. The polyanion-type compound may be a type of compound having sodium ions, transition metal ions, and a tetrahedral (YO4) n- anion unit, and the transition metal includes at least one selected from the group consisting of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce; Y includes at least one selected from the group consisting of P, S, and Si; and n represents the valence state of (YO4) n- . The polyanion-type compound may also be a compound having sodium ions, transition metal ions, and a tetrahedral (YO4) n-A compound comprising an anion unit and a halogen anion, wherein the transition metal comprises at least one selected from the group consisting of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y comprises at least one selected from the group consisting of P, S and Si, and n represents (YO4) n- The halogen includes at least one selected from the group consisting of F, Cl and Br. The polyanionic compound can also be a compound having sodium ions, tetrahedral (YO4) n- Anion unit, polyhedron unit (ZO y ) m+ and an optional halogen anion, wherein Y comprises at least one selected from the group consisting of P, S and Si, and n represents (YO4) n- valence state; Z represents a transition metal, including at least one selected from the group consisting of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, m represents (ZO y ) m+ The halogen includes at least one selected from the group consisting of F, Cl and Br. The anionic compound includes NaFePO4, Na3V2(PO4)3, NaM'PO4F (M' includes one or more selected from the group consisting of V, Fe, Mn and Ni) and Na3(VO y )2(PO4)2F 3-2y (0≤y≤1). The Prussian blue compound can be a compound having sodium ions, transition metal ions and cyanide ions (CN-). The transition metal includes at least one selected from the group consisting of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The Prussian blue compound is, for example, Na a Me b Me' c (CN)6, wherein Me and Me' each independently include at least one selected from the group consisting of Ni, Cu, Fe, Mn, Co and Zn, <a≤2,0<b<1,0<c<1。

[0090] 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.

[0091] 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.

[0092] 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.

[0093] [Negative electrode]

[0094] 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.

[0095] 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.

[0096] 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.).

[0097] 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.

[0098] 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).

[0099] 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.

[0100] In some embodiments, the negative electrode film layer may optionally include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0101] 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.

[0102] [Isolation film]

[0103] 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.

[0104] 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.

[0105] 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.

[0106] In some embodiments, the secondary battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0107] 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.

[0108] 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.

[0109] 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.

[0110] 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.

[0111] 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.

[0112] 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.

[0113] 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.

[0114] 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.

[0115] 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.

[0116] As the electrical device, a secondary battery, a battery module or a battery pack can be selected according to its usage requirements.

[0117] 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.

[0118] [Example]

[0119] 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.

[0120] Table 1

[0121] Synthesis Example 1: Compound 1 Synthesis

[0122] 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.

[0123] 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).

[0124] Synthesis Example 2: Compound 2 Synthesis

[0125] 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.

[0126] 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, 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 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 2.

[0127] Synthesis Example 3: Compound 3 Synthesis

[0128] 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.

[0129] Step 2: 205 g (0.8 mol) of intermediate product 1 was added to a 23-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., stirring was started, and 2000 g of 20% sodium hypochlorite aqueous solution was added dropwise within 1 h. 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%).

[0130] Synthesis Example 4: Compound 4 Synthesis

[0131] 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.

[0132] Step 2: 140 g (0.4 mol) of intermediate 1 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, 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 4.

[0133] Synthesis Example 5: Compound 5 Synthesis

[0134] 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.

[0135] 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 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 acetonitrile was crystallized to obtain compound 5.

[0136] In addition, the synthesis method of the compound refers to Synthesis Example 1, using the corresponding substrate in Table 2 to replace 1,6-dideoxygalactitol.

[0137] Example 1

[0138] Electrolyte composition: Compound 1 is used as an additive, and its mass content in the electrolyte is 2%; lithium hexafluorophosphate LiPF6 is used as an electrolyte, and its content in the electrolyte is 10%; a mixture of EC+EMC (ethylene carbonate+ethyl methyl carbonate) with a volume ratio of 3:7 is used as a solvent.

[0139] Positive electrode preparation:

[0140] 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.

[0141] Negative electrode preparation:

[0142] 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 the solvent deionized water in 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.

[0143] Diaphragm:

[0144] Conventional polypropylene film is used as the separator.

[0145] Lithium-ion battery assembly:

[0146] 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.

[0147] Example 2

[0148] Compound 2 was used to replace compound 1, and the rest was the same as in Example 1.

[0149] Example 3

[0150] Compound 3 was used to replace compound 1, and the rest was the same as in Example 1.

[0151] Example 4

[0152] Compound 4 was used to replace compound 1, and the rest was the same as in Example 1.

[0153] Example 5

[0154] Compound 5 was used to replace compound 1, and the rest was the same as in Example 1.

[0155] Example 6

[0156] Compound 6 was used to replace compound 1, and the rest was the same as in Example 1.

[0157] Example 7

[0158] Compound 7 was used to replace compound 1, and the rest was the same as in Example 1.

[0159] Example 8

[0160] Compound 8 was used to replace compound 1, and the rest was the same as in Example 1.

[0161] Example 9

[0162] Compound 9 was used to replace compound 1, and the rest was the same as in Example 1.

[0163] Example 10

[0164] Compound 10 was used to replace compound 1, and the rest was the same as in Example 1.

[0165] Example 11

[0166] Compound 11 was used to replace compound 1, and the rest was the same as in Example 1.

[0167] Example 12

[0168] Compound 12 was used to replace compound 1, and the rest was the same as in Example 1.

[0169] Example 13

[0170] The mass content of compound 1 was adjusted to 0.005%, and the rest was the same as in Example 1.

[0171] Example 14

[0172] The mass content of compound 1 was adjusted to 0.01%, and the rest was the same as in Example 1.

[0173] Example 15

[0174] The mass content of compound 1 was adjusted to 0.05%, and the rest was the same as in Example 1.

[0175] Example 16

[0176] The mass content of compound 1 was adjusted to 0.1%, and the rest was the same as in Example 1.

[0177] Example 17

[0178] The mass content of compound 1 was adjusted to 1%, and the rest was the same as in Example 1.

[0179] Example 18

[0180] The mass content of compound 1 was adjusted to 5%, and the rest was the same as in Example 1.

[0181] Example 19

[0182] The mass content of compound 1 was adjusted to 10%, and the rest was the same as in Example 1.

[0183] Example 20

[0184] The mass content of compound 1 was adjusted to 15%, and the rest was the same as in Example 1.

[0185] Example 21

[0186] The mass content of compound 1 was adjusted to 20%, and the rest was the same as in Example 1.

[0187] Example 22

[0188] The mass content of compound 1 was adjusted to 23%, and the rest was the same as in Example 1.

[0189] Example 23

[0190] 1,3-Propane sultone (1,3-PS) was further added to the electrolyte as a second additive, and its mass content in the electrolyte was 1%. The rest was the same as in Example 1.

[0191] Example 24

[0192] Lithium bis(fluorosulfonyl)imide (LiFSI) was used to replace lithium hexafluorophosphate, and its mass content in the electrolyte was adjusted to 15.4%. The rest was the same as in Example 1.

[0193] Example 25

[0194] Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) was used to replace lithium hexafluorophosphate, and its mass content in the electrolyte was adjusted to 23.6%. The rest was the same as in Example 1.

[0195] Example 26

[0196] Electrolyte: Sodium hexafluorophosphate (NaPF6) is used to replace lithium hexafluorophosphate, and its mass content in the electrolyte is adjusted to 13.8%. The rest is the same as Example 1.

[0197] Preparation of positive electrode sheet: The positive electrode active material NaFePO4, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are thoroughly stirred and mixed in an N-methylpyrrolidone solvent system in a mass ratio of 80:10:10, and then coated on Al foil, dried, and cold pressed to obtain a cathode sheet.

[0198] Preparation of negative electrode sheet: The negative electrode active material hard carbon, conductive agent acetylene black, and binder polyacrylic acid are thoroughly stirred and mixed in a deionized water solvent system in a mass ratio of 88:2:10, and then coated on copper foil, dried, and cold pressed to obtain an anode sheet.

[0199] The positive electrode sheet, negative electrode sheet and polypropylene separator are wound into a battery cell, which is then placed in a battery packaging shell. The prepared electrolyte is then injected, and the sodium ion battery is produced after processes such as formation and standing.

[0200] Example 27

[0201] The composition of the solvent was adjusted to a mixture of EC and EMC at a volume ratio of 5:5, and the rest was the same as in Example 1.

[0202] Example 28

[0203] Diethyl carbonate (DEC) was used to replace EMC in the solvent, and the rest was the same as in Example 1.

[0204] Example 29

[0205] Ethyl propionate was used to replace EMC in the solvent, and the rest was the same as in Example 1.

[0206] Example 30

[0207] Tetrahydrofuran (THF) was used to replace EMC in the solvent, and the rest was the same as in Example 1.

[0208] Comparative Example 1

[0209] Compound 13 was used to replace compound 1, and the rest was the same as in Example 1.

[0210] Comparative Example 2

[0211] Compound 13 was used to replace Compound 1, and its mass content in the electrolyte was adjusted to 0.5%. The rest was the same as Example 1.

[0212] Comparative Example 3

[0213] Compound 13 was used to replace Compound 1, and its mass content in the electrolyte was adjusted to 10%. The rest was the same as Example 1.

[0214] Comparative Example 4

[0215] Compound 14 was used to replace compound 1, and the rest was the same as in Example 1.

[0216] Comparative Example 5

[0217] Compound 15 was used to replace compound 1, and the rest was the same as in Example 1.

[0218] Comparative Example 6

[0219] Compound 16 was used to replace compound 1, and the rest was the same as in Example 1.

[0220] Comparative Example 7

[0221] 1,3-Propane sultone (1,3-PS) was used to replace compound 1, and the rest was the same as in Example 1.

[0222] Comparative Example 8

[0223] 1,3-PS was used to replace compound 1, and the rest were the same as in Example 26.

[0224] Performance testing:

[0225] 1) Cycle performance test

[0226] At 25°C, the lithium-ion battery is first fully discharged at 1C before testing. The test process is as follows: the lithium-ion 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 lithium-ion 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 of this time is the discharge capacity of the first cycle. The lithium-ion battery is subjected to multiple cycle charge and discharge tests according to the above method until the discharge capacity of the lithium-ion secondary battery decays to 80%. The number of cycles of the lithium-ion battery is recorded.

[0227] At 25°C, the sodium-ion battery was first fully discharged at 1C before testing. The test process is as follows: the sodium-ion battery was charged at a constant current of 0.5C to a voltage of 3.95V, then charged at a constant voltage of 3.95V to a current of 0.05C. After standing for 5 minutes, the sodium-ion battery was discharged at a constant current of 0.5C to a voltage of 1.5V. This is a charge and discharge cycle process, and the discharge capacity this time is the discharge capacity of the first cycle. The lithium-ion battery was subjected to multiple cycle charge and discharge tests according to the above method until the discharge capacity of the sodium-ion battery decayed to 80%, and the number of cycles of the sodium-ion battery was recorded.

[0228] Battery cycle capacity retention rate (%) = (discharge capacity of the battery at the Nth cycle / discharge capacity of the battery at the first cycle) × 100%.

[0229] 2) Normal temperature DCR test

[0230] At room temperature, the lithium-ion battery is charged at a constant current of 1C to 3.65V, and then charged at a constant voltage of 3.65V to a current of 0.05C. After the battery is fully charged, it is left to stand for 5 minutes, discharged at 1C for 30 minutes (the battery cell has a charge of 50% SOC), and then left to stand for 5 minutes. The temperature is adjusted to 25°C, and the battery cell is left to stand for 1 hour. The voltage V1 of the battery cell at this time is recorded. Discharge at 4C for 30 seconds, and record the voltage V2 after the pulse discharge. The DCR of the battery cell at 50% SOC discharge for 30 seconds is (V1-V2) / I, and I=4C.

[0231] At room temperature, the sodium ion battery is charged to 4.2V at a constant current of 1C, and then charged to a current of 0.05C at a constant voltage of 4.2V. After the battery is fully charged, it is left to stand for 5 minutes, discharged at 1C for 30 minutes (the battery cell is charged to 50% SOC), and then left to stand for 5 minutes. The temperature is adjusted to 25°C, left to stand for 1 hour, and the voltage V1 of the battery cell at this time is recorded. Discharge at 4C for 30 seconds, and record the voltage V2 after the pulse discharge. The DCR of the battery cell when it is discharged at 50% SOC for 30 seconds is (V1-V2) / I, and I=4C.

[0232] The test results are recorded in Table 3.

[0233] Table 3

[0234] The results of Examples 1 to 12 and Comparative Example 7 show that the introduction of a cyclic sulfate additive can effectively improve the DCR and cycle performance of the battery cell, indicating that compared with conventional sultone additives, the SEI generated by this additive at the negative electrode has lower interfacial impedance and higher stability. Compared with Comparative Examples 1, 4, 5, and 6, Example 1 shows that the introduction of Compound 1 can significantly improve the cycle performance of the battery cell. This is because the introduction of substituents such as alkyl groups can generate a longer organic chain elastic SEI 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, thereby improving the cycle performance of the battery cell.

[0235] The results of Examples 16 to 22 show that excessive additives form a thick SEI at the negative electrode, deteriorating the electrolyte conductivity and increasing the polarization of the battery cell, which, to a certain extent, deteriorates the cycling performance and DCR. When the mass percentage of the cyclic sulfonate additive in the electrolyte is within the above-mentioned preferred range, the battery cell can achieve both a low DCR and good cycling performance.

[0236] 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 an additive, wherein: The additive comprises a cyclic sulfate compound having a structure shown in general formula (I), 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 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, and n1 and n2 are each independently any integer of 0-2, The general formula (II) is 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, 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 are hydrogen atoms.

2. The nonaqueous electrolyte according to claim 1, wherein The cyclic sulfate compound has a structure represented by general 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; The general formula (II-1) is R 5 and R 6 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.

3. The nonaqueous electrolyte according to claim 1 or 2, wherein R 1 , R 2 , R 3 , R 4 , R 5 and R 6 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, a C2-C3 alkenyl group, a C1-C3 ester group, a cyano group and a sulfonic acid group; Optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 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, and a C1-C3 haloalkyl group; Optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 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 and an isopropyl group; 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; Optionally, 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 and an isopropyl group, and X is a F atom; Further optionally, R 1 , R 2 , R 3 and R 4 Each independently selected from any of a hydrogen atom, a methyl group and an ethyl group, and X is a F atom.

4. The nonaqueous electrolyte according to claim 1, wherein The cyclic sulfate compound is selected from any one or more of the following compounds:

5. The nonaqueous electrolyte according to any one of claims 1 to 4, wherein The mass content of the cyclic sulfate ester compound in the non-aqueous electrolyte is 0.001%-20%, and can be optionally 0.1%-5%.

6. The nonaqueous electrolyte according to any one of claims 1 to 5, wherein The non-aqueous electrolyte also includes an electrolyte, and optionally the electrolyte includes an alkali metal salt electrolyte; optionally the electrolyte includes a lithium salt or a sodium 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, and the sodium salt includes one or more selected from the group consisting of sodium hexafluorophosphate, sodium difluorooxalatoborate, sodium perchlorate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide and sodium trifluoromethanesulfonate.

7. The nonaqueous electrolyte according to any one of claims 1 to 6, wherein The non-aqueous electrolyte also includes a non-aqueous solvent. Optionally, the non-aqueous solvent includes any one or more of the group consisting of cyclic carbonates, chain carbonates, nitrile solvents, ketone solvents and sulfone solvents; further optionally, the non-aqueous solvent includes one or more of the group consisting of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl 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 sulfone, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, tetrahydrofuran, ethylene glycol dimethyl ether, dioxolane, acetone, acetonitrile and butyronitrile.

8. The nonaqueous electrolyte according to any one of claims 1 to 7, wherein The additive also includes one or more of sultone compounds.

9. A secondary battery comprising a positive electrode sheet, an electrolyte, a separator and a negative electrode sheet, wherein: The electrolyte is the non-aqueous electrolyte according to any one of claims 1 to 8.

10. An electrical device, comprising a secondary battery, wherein: The secondary battery includes the secondary battery according to claim 9.

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