Non-aqueous electrolyte, secondary battery, and electric device

Abstract

The present application provides a nonaqueous electrolyte, a secondary battery, and an electric device. The nonaqueous electrolyte includes an additive including a cyclic sulfate compound having a structure represented by general formula (I), wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each 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, n2, n3 are each independently any integer from 0 to 2.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a non-aqueous electrolyte, a secondary battery and an electric device. BACKGROUND

[0002] In recent years, with the development of lithium ion secondary battery technology, lithium ion secondary batteries are widely used in energy storage power systems such as hydroelectric, thermal, wind and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Due to the great development of lithium ion secondary batteries, higher requirements are put forward for their fast charging performance, cycle performance and safety performance, etc.

[0003] In battery performance, especially for lithium secondary batteries for automotive applications, long life is required. The reasons for battery life deterioration include continuous reduction of electrolyte at the negative electrode during charging. In order to overcome these problems, various compounds have been added to the electrolyte to form a passivation layer on the negative electrode surface, which is also called SEI film. The SEI film is a good lithium ion conductor and a poor electronic conductor, which inhibits the continuation of lithium consumption reaction and plays a role in protecting the electrode. Studies have shown that the formation of a solid electrolyte interface film (SEI) with uniform, dense, stable, low impedance and good adhesion properties is beneficial to improve the electrochemical performance of the battery. SUMMARY

[0004] The present application provides a non-aqueous electrolyte, a secondary battery and an electric device to improve the cycle performance of the secondary battery.

[0005] The first aspect of the present application provides a non-aqueous electrolyte comprising an additive, the additive comprising a cyclic sulfate compound having a structure represented by general formula (I),

[0006]

[0007] wherein R 1 , R 2 , R 3 and R 4 are each independently selected from any one of a group 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 independently is any one selected from the group consisting 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, n3 is any integer from 0 to 2;

[0009] R 1 and R 2 are not simultaneously a hydrogen atom and R 3 and R 4 are not simultaneously a hydrogen atom;

[0010] or, R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 satisfy the following conditions:

[0011] R 1 and R 2 are simultaneously a hydrogen atom and R 3 and R 4 one is a hydrogen atom and the other is any one selected from the group consisting 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 in the group having a structure represented by General Formula (II), R 5 and R 6 are not simultaneously a hydrogen atom;

[0012] or, R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 satisfy the following conditions:

[0013] R 3 and R 4 are simultaneously a hydrogen atom and R 1 and R 2 one is a hydrogen atom and the other is any one selected from the group consisting 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 in the group having a structure represented by General Formula (II), R 5 and R 6 are not simultaneously a hydrogen atom.

[0014] The above-mentioned cyclic sulfate compound with general formula (I) can generate more stable and electron-blocking SEI film with inorganic and organic mixed components on the negative electrode side during the first charge of the secondary battery when applied as an additive in the non-aqueous electrolyte. The SEI film can block the electron and avoid the continuous decomposition of the electrolyte on the negative electrode, thus greatly improving the cycle performance of the battery cell while having low resistance performance on the negative electrode, and further improving the battery life.

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

[0016]

[0017] R 1 , R 2 , R 3 and R 4 are each independently selected from any one of a group having a structure shown in 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] General formula (II-1) is R 5 and R 6 are each independently selected from any one of a group having a structure shown in 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.

[0019] The cyclic sulfate ring in the above-mentioned general formula (I-1) is a five-membered ring, which can form a more compact SEI film. Compared with a six-membered ring, it has a greater ring tension and is easy to form a film on the positive and negative electrodes, while the six-membered ring has a smaller ring tension, a higher stability and a slower film formation on the negative electrode, thus generating an SEI film with a lower efficiency of blocking electrons and affecting the performance of the SEI film.

[0020] In any embodiment of the first aspect, optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from any one of a group having a structure shown in 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.

[0021] In any embodiment of the first aspect, optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from any one of a group having a structure represented by Formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, and a C1-C3 haloalkyl group.

[0022] In any embodiment of the first aspect, optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from any one of a group having a structure represented by 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.

[0023] In any embodiment of the first aspect, optionally, the group having a structure represented by Formula (II-1) is selected from any one of the following groups:

[0024]

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

[0026] In any embodiment of the first aspect, optionally, R 1 , R 2 , R 3 and R 4 are 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, and X is a F atom.

[0027] In any embodiment of the first aspect, optionally, R 1 , R 2 , R 3 and R 4 are each independently selected from any one of a hydrogen atom, a methyl group, and an ethyl group, and X is a F atom.

[0028] In any embodiment of the first aspect, the cyclic sulfate compound is selected from any one or more of the following compounds:

[0029]

[0030]

[0031] The preparation method of the above-mentioned cyclic sulfate compound is simpler, more suitable for industrial promotion and implementation, and has more stable effects on improving the cycle performance of the secondary battery.

[0032] In any embodiment of the first aspect, the mass content of the above-mentioned cyclic sulfate compound in the 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%, further optionally 0.1%-5%, so as to form a sufficient SEI film with more stable and stronger electron-blocking ability by using the cyclic sulfate compound, which can not only effectively improve the cycle performance of the secondary battery, but also improve the output power of the secondary battery.

[0033] In any embodiment of the first aspect, the above-mentioned non-aqueous electrolyte further comprises an electrolyte, which optionally comprises an alkali metal salt electrolyte; the electrolyte optionally comprises a lithium salt or a sodium salt; the lithium salt optionally comprises one or more selected from the group consisting of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bisfluorosulfonylimide (LiFSI) and lithium bis-trifluoromethanesulfonylimide (LiTFSI); and the sodium salt optionally comprises one or more selected from the group consisting of sodium hexafluorophosphate, sodium difluoro oxalate borate, sodium perchlorate, sodium bisfluorosulfonylimide, sodium bis-trifluoromethanesulfonylimide and sodium trifluoromethanesulfonate. Each of the above-mentioned lithium salts can be used alone or in combination of two or more.

[0034] In any embodiment of the first aspect, the non-aqueous electrolyte further comprises a non-aqueous solvent, which comprises any one or more of the group consisting of cyclic carbonates, chain carbonates, nitrile solvents, ketone solvents and sulfone solvents. The non-aqueous solvent optionally comprises one or more of the group consisting of ethylene carbonate, propylene carbonate, methyl ethyl 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, butanediol sulfone, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, tetrahydrofuran, ethylene glycol dimethyl ether, dioxolane, acetone, acetonitrile and butyronitrile. Each of the above-mentioned non-aqueous solvents can be used alone or in combination of two or more.

[0035] In any embodiment of the first aspect, the additive further comprises one or more of a sulfonic acid lactone compound. This is to further improve the cycle performance of the battery. The second aspect of the present application provides a secondary battery comprising a positive electrode sheet, an electrolyte, a separator, and a negative electrode sheet, the electrolyte being any of the above-described non-aqueous electrolytes. The output power and the life of the secondary battery having the non-aqueous electrolyte of the present application are significantly improved.

[0036] The third aspect of the present application provides an electric device comprising a secondary battery, the secondary battery comprising any of the above-described secondary batteries. The electric device having the secondary battery of the present application has a longer service life. BRIEF DESCRIPTION OF DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced as follows. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of the drawings.

[0038] Figure 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0039] Figure 2 is a schematic diagram of a secondary battery according to an embodiment of the present application. Figure 1 is an exploded view of the secondary battery according to an embodiment of the present application.

[0040] Figure 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0041] Figure 4 is a schematic diagram of a battery pack according to an embodiment of the present application.

[0042] Figure 5 is a schematic diagram of a battery pack according to an embodiment of the present application. Figure 4 is an exploded view of the battery pack according to an embodiment of the present application.

[0043] Figure 6 is a schematic diagram of an electric device using the secondary battery according to an embodiment of the present application as a power source.

[0044] In the drawings, the drawings are not drawn according to the actual scale.

[0045] Explanation of Reference Signs:

[0046] 1 battery pack; 2 upper case; 3 lower case; 4 battery module; 5 secondary battery; 51 housing; 52 electrode assembly; 53 top cap assembly. DETAILED DESCRIPTION

[0047] The embodiments of the present application will be described in further detail below with reference to the accompanying drawings and examples. The following detailed description of the examples and the accompanying drawings are provided to illustrate the principles of the present application, and should not be taken in a limiting sense. The present application is not limited to the examples described.

[0048] Hereinafter, specific embodiments of the nonaqueous electrolyte solution, the secondary battery, and the electric device of the present application are described in detail with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed description is omitted. For example, there are cases where detailed description of matters known well, and repetitive description of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy, and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0049] The "ranges" disclosed in the present application are defined in the form of lower and upper limits, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this manner can include the end values or can not include the end values, and can be arbitrarily combined, i.e., any lower limit can be combined with any upper limit to form a range. For example, if the ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values of 1 and 2 are listed, and if the maximum range values of 3, 4, and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In the present application, unless otherwise specified, a numerical range "a-b" represents a shorthand manner of describing each and every numerical value that is contained within the range, wherein a and b are both real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed herein, and "0-5" is merely a shorthand manner of describing each and every numerical value that is contained within the range. In addition, when it is stated that a parameter is an integer ≥ 2, it is equivalent to disclose that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, and the like.

[0050] If not specifically stated, all embodiments of the present application and optional embodiments can be combined with each other to form new technical solutions.

[0051] If not specifically stated, all technical features of the present application and optional technical features can be combined with each other to form new technical solutions.

[0052] If not specifically stated, all steps of the present application can be performed in sequence or randomly, preferably in sequence. For example, the method comprises steps (a) and (b) means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c) means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0053] If not specifically stated, the present application refers to "including" and "comprising" as open-ended, and can also be closed. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0054] If not specifically stated, in the present application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any one of the following conditions satisfies the condition "A or B": 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 A and B are both true (or exist).

[0055] [Secondary battery]

[0056] A secondary battery, also known as a rechargeable battery or a storage battery, refers to a battery that can continue to be used by activating the active material through charging after the battery is discharged.

[0057] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (such as lithium ions or sodium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuiting of the positive and negative electrodes, while allowing the active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet, mainly to conduct the active ions.

[0058] [Non-aqueous electrolyte]

[0059] An embodiment of the present application provides a non-aqueous electrolyte, comprising an additive, the additive comprising a cyclic sulfate compound having a structure represented by general formula (I),

[0060]

[0061] wherein R 1 , R 2 , R 3 and R 4each independently is 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, n1 and n2 are each independently any integer from 0 to 2;

[0062] General Formula (II) is R 5 and R 6 each independently is 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, n3 is any integer from 0 to 2,

[0063] R 1 and R 2 are not simultaneously a hydrogen atom and R 3 and R 4 are not simultaneously a hydrogen atom;

[0064] Alternatively, R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 satisfy the following conditions:

[0065] R 1 and R 2 are simultaneously 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 the group having a structure represented by General Formula (II) is 5 and R 6 are not simultaneously a hydrogen atom;

[0066] Alternatively, R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 satisfy the following conditions:

[0067] R 3 and R 4 are simultaneously a hydrogen atom and R 1 and R 2one is a hydrogen atom and the other is any one of a hydrogen atom, 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 the group having a structure represented by general formula (II) is a group represented by general formula (II) in which R 5 and R 6 are not simultaneously a hydrogen atom.

[0068] The above-mentioned cyclic sulfate compound having general formula (I) can generate a more stable and more electron-blocking inorganic and organic mixed SEI film on the negative electrode side during the first charging process of a secondary battery when applied as an additive in a non-aqueous electrolyte. The SEI film can block electrons and avoid continuous decomposition of the electrolyte at the negative electrode, thereby greatly improving the cycle performance of the battery and significantly improving the service life of the battery.

[0069] The mechanism by which the above-mentioned cyclic sulfate compound achieves the above-mentioned effects is not clear, but the applicant speculates that, on the basis of the skeleton of the cyclic sulfate compound having two cyclic sulfate rings, the introduction of an alkyl group or the like can generate an elastic SEI film with a longer organic chain at the negative electrode, which can cope with the volume change of the negative electrode during the cycle process and avoid the destruction of the SEI film; the introduction of a F-containing and N-containing substituent group can participate in the film formation at the negative electrode to generate an SEI film rich in more inorganic components such as LiF and Li3N, thereby improving the mechanical strength of the SEI film and further improving the stability of the negative electrode SEI film to achieve the purpose of improving the cycle performance of the battery.

[0070] The above-mentioned alkyl group can be a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, including but not limited to a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a cyclopropane group, a cyclobutane group, etc.; the alkyl group in the above-mentioned haloalkyl group includes but is not limited to a linear alkyl group, a branched alkyl group, or a cyclic alkyl group, such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a cyclopropane group, a cyclobutane group, etc.; the halogen atom can be a fluorine atom, a chlorine atom, or a bromine atom, and the halogen atom can replace 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 can be a fluorine atom, a chlorine atom, or a bromine atom, and the halogen atom can replace 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 a formate methyl group, a formate ethyl group, an ethyl acetate group, a methyl propionate group, an ethyl propionate group, a propyl propionate group, etc.

[0071] In some embodiments of the present application, the above-mentioned cyclic sulfate compound has a structure represented by general formula (I-1),

[0072]

[0073] R 1 , R 2 , R 3 and R 4 are each independently selected from any one of a group having a structure shown in 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;

[0074] General formula (II-1) is R 5 and R 6 are each independently selected from any one of a group having a structure shown in 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.

[0075] The cyclic sulfate ring in the above general formula (I-1) is a five-membered ring, which can form a more compact SEI film. Compared with a six-membered ring, it has a larger ring tension, is easy to form a film on the positive and negative electrodes, and the six-membered ring has a smaller ring tension, a higher stability and a slower film formation on the negative electrode, so that the efficiency of generating an electron-blocking SEI film is lower, which affects the exertion of the SEI film effect.

[0076] In some embodiments of the present application, optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from any one of a group having a structure shown in 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.

[0077] In some embodiments of the present application, optionally, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 are each independently selected from any one of a group having a structure shown in general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, a C1-C3 haloalkyl group.

[0078] In some embodiments of the present application, optionally, R1 R 2 R 3 R 4 R 5 and R 6 Each is independently selected from any one of the groups having the structure shown in general formula (Ⅱ-1), hydrogen atoms, F atoms, Cl atoms, Br atoms, methyl, ethyl, propyl and isopropyl groups.

[0079] In some embodiments of this application, optionally, the group representing the structure of general formula (Ⅱ-1) is selected from any one of the following groups:

[0080]

[0081] Where X is an F atom, a Cl atom, or a Br atom.

[0082] In some embodiments of this application, R may optionally be used. 1 R 2 R 3 and R 4 Each independently selected X is any one of hydrogen atom, F atom, Cl atom, Br atom, methyl, ethyl, propyl and isopropyl, where X is an F atom.

[0083] In some embodiments of this application, R may optionally be used. 1 R 2 R 3 and R 4 Each independently selected Any one of hydrogen atom, methyl, and ethyl, where X is an F atom.

[0084] In some embodiments of this application, the above-mentioned cyclic sulfate compound is selected from any one or more of the following compounds:

[0085]

[0086]

[0087] The preparation methods of some of the aforementioned cyclic sulfate compounds are simpler, easier to promote and implement in industry, and have a more stable effect on improving the lifespan of secondary batteries.

[0088] The amount of the cyclic sulfate compound in each of the above embodiments of the present application can refer to the amount of a conventional cyclic sulfate compound in a conventional non-aqueous electrolyte. 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%. The use of the cyclic sulfate compound to form a sufficient SEI film with more stable and stronger barrier electron capability not only effectively improves the cycle performance of the secondary battery, but also improves the output power of the secondary battery. By limiting the mass content as above, the SEI film effect cannot be fully exerted due to too little cyclic sulfate compound, and the electrolyte viscosity is too large and the SEI film formed at the negative electrode is too thick due to too much cyclic sulfate compound, which deteriorates the conductivity of the electrolyte, and further deteriorates the improvement effect of the cycle performance and the charging capability.

[0089] In some embodiments, the non-aqueous electrolyte further comprises an electrolyte, and any electrolyte commonly 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 select according to the battery system to which the non-aqueous electrolyte is applied, such as selecting a conventional electrolyte suitable for a lithium ion secondary battery or a sodium ion secondary battery. In some embodiments, the electrolyte in the above non-aqueous electrolyte comprises an alkali metal salt electrolyte; optionally, the electrolyte comprises 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 bisfluorosulfonylimide (LiFSI), lithium bis-trifluoromethanesulfonylimide (LiTFSI), and the sodium salt comprises one or more selected from the group consisting of sodium hexafluorophosphate, sodium difluoro oxalate borate, sodium perchlorate, sodium bisfluorosulfonylimide, sodium bis-trifluoromethanesulfonylimide, and sodium trifluoromethanesulfonate. Each of the above lithium salt or sodium salt can be used alone or in combination of two or more.

[0090] The content of the electrolyte in the non-aqueous electrolyte can refer to the content of the electrolyte in a conventional non-aqueous electrolyte. In some embodiments, the content of the electrolyte in the non-aqueous electrolyte is 0.1 mol / L-5 mol / L, such as 0.1 mol / L, 0.3 mol / L, 0.5 mol / L, 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 4 mol / L, or 5 mol / L, optionally 0.5 mol / L-1.5 mol / L, and further optionally 0.7 mol / L-1.2 mol / L.

[0091] The non-aqueous solvent of the present application can be selected from conventional non-aqueous solvents for secondary batteries, and 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. Alternatively, 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, 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, butanediol sulfone, 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, such as a mixed solvent of cyclic carbonates and chain carbonates, in order to improve the load characteristics or low-temperature characteristics of the secondary battery. When the non-aqueous electrolyte of the present application is applied to a solid battery, a solid solvent such as dimethyl sulfone can be used.

[0092] In addition to the above additives, the additives can also include negative electrode film-forming additives, positive electrode film-forming additives, and can also include additives capable of improving certain properties of the battery, such as additives for improving the overcharge performance of the battery, additives for improving the high-temperature or low-temperature performance of the battery, and the like. In some embodiments, the above additives further include one or more of sulfonic acid lactone compounds. By adding sulfonic acid lactone compounds, the cycle performance of the secondary battery is further improved.

[0093] [Method for preparing cyclic sulfate compounds having the structure shown in general formula (I)]

[0094] The method for preparing cyclic sulfate compounds having the structure shown in general formula (I) of the present application is described with reference to the following synthesis route:

[0095]

[0096] In the first step, the reaction temperature is controlled at 30-60°C; in the second step, the reaction temperature is controlled at 10-30°C, and a catalyst such as ruthenium trichloride trihydrate is used for catalysis, and the oxidant can be sodium hypochlorite, ozone, etc.

[0097] [Positive electrode tab]

[0098] The positive electrode tab 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, and the positive electrode film layer includes a positive electrode active material.

[0099] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is provided on either one or both of the two opposite surfaces of the positive electrode current collector.

[0100] In some embodiments, the positive electrode current collector can employ a metal foil or a composite current collector. For example, as the metal foil, an aluminum foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base material (e.g., a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0101] In some embodiments, the positive electrode active material can employ 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 can include at least one of a lithium-containing phosphate of an olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive electrode active material for a battery can also be used. These positive electrode active materials can be used alone only one or in combination of two or more. Examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to simply as NCM 333 ). Examples of the lithium-containing phosphate of an olivine structure can include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can also be referred to simply as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0102] As an example, the positive active material for a sodium-ion secondary battery can include at least one of at least one of a sodium transition metal oxide, a polyanion compound, and a Prussian blue compound. However, the present application is not limited to these materials, and other conventional materials that can be used as a battery positive active material can also be used. These positive active materials can be used alone or in combination of two or more. Among them, the sodium transition metal oxide includes at least one of transition metals 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 more selected from the group consisting of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≤ 1. The polyanion compound can be a compound having a sodium ion, a transition metal ion, and a tetrahedral (YO4) n- anion unit, 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 of (YO4) n- . The polyanion compound can also be a compound having a sodium ion, a transition metal ion, a tetrahedral (YO4) n- anion unit, and a halogen anion, 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; n represents the valence of (YO4) n- ; and the halogen includes at least one selected from the group consisting of F, Cl, and Br. The polyanion compound can also be a compound having a sodium ion, a tetrahedral (YO4) n- anion unit, a polyhedral (ZO y ) m+ ) n- )2, and an optional halogen anion, Y includes at least one selected from the group consisting of P, S, and Si; n represents the valence of (YO4) y ; 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 the valence of (ZO m+ ) y )2, and an optional halogen anion, Y includes at least one selected from the group consisting of P, S, and Si; n represents the valence of (YO4) 3-2yat least one selected from the group consisting of (0≤y≤1). The Prussian blue type 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 type 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, 0

[0103] In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder can 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 acrylic resin.

[0104] In some embodiments, the positive electrode film layer further optionally includes a conductive agent. As an example, the conductive agent can include at least one of super P, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0105] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and then drying, cold-pressing, and the like to obtain the positive electrode tab.

[0106] [Negative electrode tab]

[0107] The negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0108] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0109] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0110] In some embodiments, the negative active material can employ a negative active material for a battery known in the art. As an example, the negative active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, and lithium titanate, etc. The silicon-based material can be selected from at least one of elemental silicon, silicon oxide compound, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy. The tin-based material can be selected from at least one of elemental tin, tin oxide compound, and tin alloy. However, the present application is not limited to these materials, and other conventional materials that can be used as a negative active material for a battery can also be used. These negative active materials can be used alone or in combination of two or more.

[0111] In some embodiments, the negative film layer can further optionally include a binder. As an example, the binder can 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).

[0112] In some embodiments, the negative film layer can further optionally include a conductive agent. As an example, the conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0113] In some embodiments, the negative film layer can further optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0114] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-described components for preparing the negative electrode sheet, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry, coating the negative electrode slurry on a negative current collector, and then performing processes such as drying, cold pressing, etc.

[0115] [Separator]

[0116] In some embodiments, the secondary battery further comprises a separator. The type of the separator is not particularly limited in the present application, and any known porous separator having good chemical stability and mechanical stability can be used.

[0117] 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, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0118] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be used to form an electrode assembly by a winding process or a stacking process.

[0119] In some embodiments, the secondary battery can comprise an outer package. The outer package can be used to package the electrode assembly and the electrolyte described above.

[0120] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as the plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0121] The shape of the secondary battery is not particularly limited in the present application, and it can be cylindrical, square, or any other shape. For example, Figure 1 is a square structure secondary battery 5 as an example.

[0122] In some embodiments, referring to Figure 2 , the outer package can comprise a shell 51 and a cover plate 53. The shell 51 can comprise 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 communicating with the receiving cavity, and the cover plate 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can be used to form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of electrode assemblies 52 contained in the secondary battery 5 can be one or more, and the person skilled in the art can select according to the specific actual needs.

[0123] In some embodiments, the secondary battery can be assembled into a battery module, and the number of secondary batteries contained in the battery module can be one or more, and the specific number can be selected by the person skilled in the art according to the application and capacity of the battery module.

[0124] Figure 3 is a battery module 4 as an example. Referring to Figure 3In the battery module 4, the plurality of secondary batteries 5 can be arranged in series along the length direction of the battery module 4. Of course, the plurality of secondary batteries 5 can be arranged in any other manner. The plurality of secondary batteries 5 can be further fixed by fasteners.

[0125] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of secondary batteries 5 can be accommodated in the accommodation space.

[0126] In some embodiments, the above-described battery module can be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0127] Figure 4 and Figure 5 is a battery pack 1 as an example. Referring to Figure 4 and Figure 5 In the battery pack 1, a battery box and a plurality of battery modules 4 arranged in the battery box can be included. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be arranged on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0128] In addition, the application also provides a power utilization device, which includes at least one of the secondary battery, the battery module, or the battery pack provided by the application. The secondary battery, the battery module, or the battery pack can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0129] As the power utilization device, the secondary battery, the battery module, or the battery pack can be selected according to the use requirements thereof.

[0130] Figure 6 is a power utilization device as an example. The power utilization device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the high power and high energy density requirements of the secondary battery for the power utilization device, a battery pack or a battery module can be used.

[0131] [Embodiment]

[0132] The following describes the examples of the present application. The examples described below are exemplary and are for the purpose of explanation of the present application and cannot be understood as a limitation of the present application. In the examples, the specific techniques or conditions not noted are performed in accordance with the techniques or conditions described in the literature in the field or in accordance with the product manual. The reagents or instruments not noted as to the manufacturer are all conventional products that can be obtained commercially, and the remaining reagent or compound information is recorded in Table 1.

[0133] Table 1

[0134]

[0135]

[0136] Synthesis Example 1: Compound 1 Synthesis of Compound 1

[0137] Step 1: 300 g (2 mol) of solid 1,6 dideoxygalactitol 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 dropwise addition, and after the dropwise addition was completed, the reaction was incubated at 45°C for 4 h, a large amount of paste-like solid was precipitated from the reaction liquid, deionized water 1 L was slowly added dropwise after cooling, the reaction system was quickly stirred and dispersed, and the obtained solid was washed with deionized water for several times until the pH was neutral, the filter cake was dried at 60°C under reduced pressure, and the intermediate product was obtained.

[0138] Step 2: 184.2 g (0.8 mol) of the intermediate product 1 was added to a 3 L three-necked flask, 1000 mL of acetonitrile was added, 80 mg of ruthenium trichloride trihydrate catalyst was added, the system was replaced with nitrogen, the system was cooled to 20°C, stirring was started, 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 dropwise addition was completed, the system was stirred at 10-20°C for 10 min, the liquid was separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch iodide potassium test paper did not turn blue; the liquid was separated again, the organic layer was concentrated, acetonitrile was crystallized, and white powder solid was obtained, which was the above-mentioned compound 1. 1H-NMR, CD3CN, δ ppm 5.42-5.39 (m, 2H), 5.36-5.34 (m, 2H), 1.67-1.65 (d, 6H).

[0139] Synthesis Example 2: Compound 2 Synthesis of Compound 2

[0140] Step 1: 356.5 g (2 mol) of solid 3,4,5,6-octanetetraol 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 flask, the temperature was controlled at about 15°C during the dropwise addition, and after the dropwise addition was completed, the reaction was maintained at 45°C for 4 h, a large amount of paste-like solid was precipitated from the reaction solution, deionized water 1 L was slowly added dropwise after cooling, the reaction system was quickly stirred and dispersed, the obtained solid was washed with deionized water for several times until the pH was neutral, and the filter cake was dried at 60°C under reduced pressure to obtain an intermediate product.

[0141] Step 2: 216.2 g (0.8 mol) of the intermediate product 1 was added to a 3 L three-necked flask, 1000 mL of acetonitrile was added, 80 mg of ruthenium trichloride trihydrate catalyst was added, the system was replaced with nitrogen, the system was cooled to 20°C, stirring was started, 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 dropwise addition was completed, stirring was performed at 10-20°C for 10 min, the liquid was separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch iodide paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 2.

[0142] Synthesis of compound 3 Synthesis of compound 4

[0143] Step 1: 328.4 g (2 mol) of solid 2,3,4,5-heptanetetraol 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 flask, the temperature was controlled at about 15°C during the dropwise addition, and after the dropwise addition was completed, the reaction was maintained at 45°C for 4 h, a large amount of paste-like solid was precipitated from the reaction solution, deionized water 1 L was slowly added dropwise after cooling, the reaction system was quickly stirred and dispersed, the obtained solid was washed with deionized water for several times until the pH was neutral, and the filter cake was dried at 60°C under reduced pressure to obtain an intermediate product.

[0144] Step 2: 205 g (0.8 mol) of the intermediate product 1 was added to a 23 three-necked flask, 1000 mL of acetonitrile was added, and stirring was performed until the solid was completely dissolved, 80 mg of ruthenium trichloride trihydrate catalyst was added, the system was replaced with nitrogen, the system was cooled to 20°C, stirring was started, 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 dropwise addition was completed, stirring was performed at 10-20°C for 10 min, the liquid was separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch iodide paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 3 (163.1 g, yield 82.8%).

[0145] Synthesis of compound 4 Synthesis of compound 4

[0146] Step 1: 392.4 g (2 mol) of solid 1,2,3,4,5.6-heptulose 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 flask, the temperature was controlled at about 15°C during the dropwise addition, and after the dropwise addition was completed, the reaction was incubated at 45°C for 4 h, a large amount of paste-like solid was precipitated from the reaction solution, deionized water 1 L was slowly added dropwise after cooling, the reaction system was quickly stirred and dispersed, the obtained solid was washed with deionized water for several times until the pH was neutral, and the filter cake was dried at 60°C under reduced pressure to obtain an intermediate product.

[0147] Step 2: 140 g (0.4 mol) of the intermediate product 1 was added to a 4 L three-necked flask, 1000 mL of acetonitrile was added, 110 mg of ruthenium trichloride trihydrate catalyst was added, the system was replaced with nitrogen, 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, the reaction temperature was controlled at 10-20°C; after the dropwise addition was completed, the system was stirred at 10-20°C for 10 min, the liquid was separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch iodide paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 4.

[0148] Synthesis of compound 5

[0149] Step 1: 484 g (2 mol) of solid octitol was added to a 2 L three-necked flask, stirring was started, and 1046 g (8.8 mol) of thionyl chloride was added dropwise to the flask, the temperature was controlled at about 15°C during the dropwise addition, and after the dropwise addition was completed, the reaction was incubated at 45°C for 4 h, a large amount of paste-like solid was precipitated from the reaction solution, deionized water 1 L was slowly added dropwise after cooling, the reaction system was quickly stirred and dispersed, the obtained solid was washed with deionized water for several times until the pH was neutral, and the filter cake was dried at 60°C under reduced pressure to obtain an intermediate product.

[0150] Step 2: 183.2 g (0.4 mol) of the intermediate product was added to a 4 L three-necked flask, 1000 mL of acetonitrile was added, 150 mg of ruthenium trichloride trihydrate catalyst was added, the system was replaced with nitrogen, 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 dropwise addition was completed, the system was stirred at 10-20°C for 10 min, the liquid was separated, and the organic phase was quenched with sodium sulfite aqueous solution until the starch iodide paper did not turn blue; the liquid was separated again, the organic layer was concentrated, and acetonitrile was crystallized to obtain compound 5.

[0151] In addition, the synthesis method of the compound refers to synthesis example 1, and 1,6 dideoxygalactitol in table 2 is used to replace the corresponding substrate.

[0152]

[0153] ​

[0154] Example 1

[0155] Electrolyte composition: compound 1 as an additive, the mass content of which in the electrolyte is 2%; lithium hexafluorophosphate LiPF6 is used as an electrolyte, the content of which in the electrolyte is 10%, and a mixture of EC+EMC (ethylene carbonate+ethyl methyl carbonate) in a volume ratio of 3:7 is used as a solvent.

[0156] Preparation of positive electrode sheet:

[0157] The positive electrode active material lithium iron phosphate (LiFeP04), the conductive agent acetylene black and the binder polyvinylidene fluoride (PVDF) are dissolved in the solvent N-methyl pyrrolidone (NMP) in a weight ratio of 90:5:5, and after being fully stirred and mixed uniformly, a positive electrode slurry is obtained; then the positive electrode slurry is uniformly coated on the positive electrode current collector, and after drying, cold pressing and slitting, a positive electrode sheet is obtained.

[0158] Preparation of negative electrode sheet:

[0159] The negative electrode active material graphite, the conductive agent carbon black, the binder styrene butadiene rubber (SBR) and the thickening agent sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water in a weight ratio of 90:4:4:2, and after being mixed uniformly, a negative electrode slurry is prepared; the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil one or more times, and after drying, cold pressing and slitting, a negative electrode sheet is obtained.

[0160] Separator:

[0161] A conventional polypropylene film is used as a separator film.

[0162] Assembly of lithium ion battery:

[0163] The positive electrode sheet, the separator film and the negative electrode sheet are stacked in order, with the separator film between the positive electrode sheet and the negative electrode sheet to play a separating role, and then wound to obtain an electrode assembly; the electrode assembly is placed in a battery shell, dried, and then injected with electrolyte, and after processes such as formation and standing, a lithium ion battery is prepared.

[0164] Example 2

[0165] Compound 2 is used to replace compound 1, and the rest is the same as example 1.

[0166] Example 3

[0167] Compound 3 is used to replace compound 1, and the rest is the same as example 1.

[0168] Example 4

[0169] Compound 4 is used to replace compound 1, and the rest is the same as example 1.

[0170] Example 5

[0171] Example 1 using compound 5 in place of compound 1.

[0172] Example 6

[0173] Example 1 using compound 6 in place of compound 1.

[0174] Example 7

[0175] Example 1 using compound 7 in place of compound 1.

[0176] Example 8

[0177] Example 1 using compound 8 in place of compound 1.

[0178] Example 9

[0179] Example 1 using compound 9 in place of compound 1.

[0180] Example 10

[0181] Example 1 using compound 10 in place of compound 1.

[0182] Example 11

[0183] Example 1 using compound 11 in place of compound 1.

[0184] Example 13

[0185] Example 1 with the mass content of compound 1 adjusted to 0.005%.

[0186] Example 14

[0187] Example 1 with the mass content of compound 1 adjusted to 0.01%.

[0188] Example 15

[0189] Example 1 with the mass content of compound 1 adjusted to 0.05%.

[0190] Example 16

[0191] Example 1 with the mass content of compound 1 adjusted to 0.1%.

[0192] Example 17

[0193] Example 1 with the mass content of compound 1 adjusted to 1%.

[0194] Example 18

[0195] The mass content of compound 1 is adjusted to 5%, and the rest is the same as example 1.

[0196] Example 19

[0197] The mass content of compound 1 is adjusted to 10%, and the rest is the same as example 1.

[0198] Example 20

[0199] The mass content of compound 1 is adjusted to 15%, and the rest is the same as example 1.

[0200] Example 21

[0201] The mass content of compound 1 is adjusted to 20%, and the rest is the same as example 1.

[0202] Example 22

[0203] The mass content of compound 1 is adjusted to 23%, and the rest is the same as example 1.

[0204] Example 23

[0205] 1,3-propane sultone (1,3-PS) is continuously added to the electrolyte as a second additive, and the mass content of 1,3-propane sultone in the electrolyte is 1%, and the rest is the same as example 1.

[0206] Example 24

[0207] Lithium bisfluorosulfonylimide (LiFSI) is used to replace lithium hexafluorophosphate, and the mass content of lithium bisfluorosulfonylimide in the electrolyte is adjusted to 15.4%, and the rest is the same as example 1.

[0208] Example 25

[0209] Lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) is used to replace lithium hexafluorophosphate, and the mass content of lithium bis(trifluoromethylsulfonyl)imide in the electrolyte is adjusted to 23.6%, and the rest is the same as example 1.

[0210] Example 26

[0211] Electrolyte: sodium hexafluorophosphate (NaPF6) is used to replace lithium hexafluorophosphate, and the mass content of sodium hexafluorophosphate in the electrolyte is adjusted to 13.8%, and the rest is the same as example 1.

[0212] Positive electrode sheet preparation: the positive electrode active material NaFePO4, the conductive agent acetylene black, and the binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 80:10:10 in an N-methyl pyrrolidone solvent system, and then coated on an Al foil, dried, and cold-pressed to obtain a cathode sheet.

[0213] Negative electrode sheet preparation: the negative active material hard carbon, conductive agent acetylene black, and binder polyacrylic acid were mixed in a mass ratio of 88:2:10 in a deionized water solvent system, and then coated on a copper foil, dried, and cold-pressed to obtain the anode sheet.

[0214] The positive electrode sheet, the negative electrode sheet, and the polypropylene separator film were wound to form an electric core, which was then placed in a battery packaging shell, and then the prepared electrolyte was injected, and the sodium-ion battery was prepared through processes such as formation and standing.

[0215] Example 27

[0216] The composition of the solvent was adjusted to be a mixture of EC+EMC in a volume ratio of 5:5, and the rest was the same as in Example 1.

[0217] Example 28

[0218] Diethyl carbonate (DEC) was used to replace EMC in the solvent, and the rest was the same as in Example 1.

[0219] Example 29

[0220] Ethyl propionate was used to replace EMC in the solvent, and the rest was the same as in Example 1.

[0221] Example 30

[0222] Tetrahydrofuran (THF) was used to replace EMC in the solvent, and the rest was the same as in Example 1.

[0223] Comparative Example 1

[0224] Compound 13 was used to replace Compound 1, and the rest was the same as in Example 1.

[0225] Comparative Example 2

[0226] Compound 13 was used to replace Compound 1, and its mass content in the electrolyte was adjusted to 0.5%, and the rest was the same as in Example 1.

[0227] Comparative Example 3

[0228] Compound 13 was used to replace Compound 1, and its mass content in the electrolyte was adjusted to 10%, and the rest was the same as in Example 1.

[0229] Comparative Example 4

[0230] Compound 14 was used to replace Compound 1, and the rest was the same as in Example 1.

[0231] Comparative Example 5

[0232] Compound 15 was used to replace Compound 1, and the rest was the same as in Example 1.

[0233] Comparative Example 6

[0234] Example 1 was replaced by compound 16, and the rest was the same as example 1.

[0235] Comparative example 7

[0236] Example 1 was replaced by 1,3-propane sultone (1,3-PS), and the rest was the same as example 1.

[0237] Comparative example 8

[0238] Example 26 was replaced by 1,3-PS, and the rest was the same as example 26.

[0239] Performance test:

[0240] 1), cycle performance test

[0241] At 25°C, the lithium ion battery was first fully discharged at 1C and then tested. The test process was as follows: the lithium ion battery was charged at 0.5C constant current to voltage 3.65V, then charged at 3.65V constant voltage to current 0.05C, and after standing for 5min, the lithium ion battery was discharged at 0.5C constant current to voltage 2.5V, which was a charge-discharge cycle process. The discharge capacity of this time was the discharge capacity of the first cycle. The lithium ion battery was tested by multiple cycle charge-discharge according to the above method, until the discharge capacity of the lithium ion secondary battery decayed to 80%, and the cycle number of the lithium ion battery was recorded.

[0242] At 25°C, the sodium ion battery was first fully discharged at 1C and then tested. The test process was as follows: the sodium ion battery was charged at 0.5C constant current to voltage 3.95V, then charged at 3.95V constant voltage to current 0.05C, and after standing for 5min, the sodium ion battery was discharged at 0.5C constant current to voltage 1.5V, which was a charge-discharge cycle process. The discharge capacity of this time was the discharge capacity of the first cycle. The lithium ion battery was tested by multiple cycle charge-discharge according to the above method, until the discharge capacity of the sodium ion battery decayed to 80%, and the cycle number of the sodium ion battery was recorded.

[0243] Battery cycle capacity retention rate (%) = (discharge capacity of battery in the Nth cycle / discharge capacity of battery in the first cycle) x 100%.

[0244] 2), normal temperature DCR test

[0245] The lithium ion battery was charged at 1C constant current to 3.65V at room temperature, and then charged at constant voltage of 3.65V until the current was 0.05C. After the battery was fully charged, it was rested for 5min, discharged at 1C for 30min (the battery had a charge of 50% SOC), and then rested for 5min. The temperature was adjusted to 25°C, and the battery was rested for 1h, and the voltage V1 of the battery at this time was recorded. The battery was discharged at 4C for 30s, and the voltage V2 after pulse discharge was recorded, and then the DCR of the battery at 50% SOC when discharged for 30s was (V1-V2) / I, I=4C.

[0246] The sodium ion battery was charged at 1C constant current to 4.2V at room temperature, and then charged at constant voltage of 4.2V until the current was 0.05C. After the battery was fully charged, it was rested for 5min, discharged at 1C for 30min (the battery had a charge of 50% SOC), and then rested for 5min. The temperature was adjusted to 25°C, and the battery was rested for 1h, and the voltage V1 of the battery at this time was recorded. The battery was discharged at 4C for 30s, and the voltage V2 after pulse discharge was recorded, and then the DCR of the battery at 50% SOC when discharged for 30s was (V1-V2) / I, I=4C.

[0247] The test results are recorded in Table 3.

[0248] Table 3

[0249]

[0250]

[0251] As can be seen from the results of Examples 1-12 and Comparative Example 7, by introducing the cyclic sulfate additive, the DCR and cycle performance of the battery can be effectively improved, indicating that compared with the conventional sulfonic acid lactone additive, the additive has lower interface impedance and high stability in the SEI generated at the negative electrode. Compared with Comparative Examples 1, 4, 5 and 6, the introduction of compound 1 can significantly improve the cycle performance of the battery, because the introduction of alkyl and other substituents can generate an elastic SEI with a longer organic chain at the negative electrode, which can cope with the volume change of the negative electrode during the cycle process to avoid the destruction of the SEI, thereby improving the cycle performance of the battery.

[0252] As can be seen from the results of Examples 16-22, too much additive generates a thicker SEI at the negative electrode, which deteriorates the conductivity of the electrolyte, leading to an increase in polarization of the battery, which will deteriorate the cycle performance and DCR to some extent. When the mass ratio of the cyclic sulfonic ester additive of the application in the electrolyte is within the above preferred range, the battery can have a lower DCR and better cycle performance.

[0253] Although the present application has been described with reference to preferred embodiments, various modifications can be made to the application without departing from the scope of the application. In particular, the technical features mentioned in the various embodiments can be combined in any way, provided that there is no structural conflict. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A nonaqueous electrolyte comprising an additive, wherein, The additive includes a cyclic sulfate compound having a structure represented by general formula (I), General formula (I) wherein R 1 , R 2 , R 3 and R 4 are each independently selected from any one of a group having a structure shown in 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, n1 and n2 are each independently any integer of 0-2, General Formula (II) is , R 5 and R 6 each independently is selected from any one of a group having the structure shown in 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 simultaneously hydrogen atoms and R 3 and R 4 are not simultaneously hydrogen atoms; or R 1 , R 2 , R 3 , R 4 , R 5 and R 6 satisfy the following conditions: R 1 and R 2 are simultaneously hydrogen atoms 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 the group having a structure represented by general formula (II) is a group in which R 5 and R 6 are not simultaneously hydrogen atoms; or R 1 , R 2 , R 3 , R 4 , R 5 and R 6 satisfy the following conditions: R 3 and R 4 are simultaneously hydrogen atoms 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 the group having a structure represented by general formula (II) is a group in which R 5 and R 6 are not simultaneously hydrogen atoms.

2. The nonaqueous electrolyte according to claim 1, wherein The cyclic sulfate compound has a structure represented by general formula (I-1), General formula (I-1) R 1 , R 2 , R 3 , and R 4 are each independently selected from any one of a group having a structure shown in 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; General Formula (II-1) is R 5 and R 6 each independently is selected from any one of a group having a structure shown in 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 are each independently selected from any one of a group having a structure shown in 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.

4. The nonaqueous electrolyte according to claim 1 or 2, wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each independently selected from any one of a group having a structure shown in general formula (II-1), a hydrogen atom, a halogen atom, a C1-C3 alkyl group, and a C1-C3 haloalkyl group.

5. The nonaqueous electrolyte according to claim 1 or 2, wherein R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 are each independently selected from any one of a group having a structure shown in 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.

6. The nonaqueous electrolyte according to claim 1 or 2, wherein the group represented by general formula (II-1) is selected from any one of the following groups: 、 、 、 、 、 wherein X is an F atom, a CI atom or a Br atom.

7. The nonaqueous electrolyte according to claim 1 or 2, wherein R 1 R 2 R 3 and R 4 Each independently selected , , , , , X is any one of hydrogen atom, F atom, Cl atom, Br atom, methyl, ethyl, propyl and isopropyl, where X is an F atom.

8. The nonaqueous electrolyte according to claim 1 or 2, wherein R 1 , R 2 , R 3 and R 4 are each independently selected from the group consisting of , , , , a hydrogen atom, a methyl group and an ethyl group, and X is a F atom.

9. The nonaqueous electrolyte according to claim 1, wherein The cyclic sulfate compound is selected from any one or more of the following compounds: 。 10. The nonaqueous electrolyte according to claim 1 or 2, wherein The mass content of the cyclic sulfate compound in the nonaqueous electrolyte is 0.001%-20%.

11. The nonaqueous electrolyte according to claim 1 or 2, wherein The mass content of the cyclic sulfate compound in the nonaqueous electrolyte is 0.1%-5%.

12. The nonaqueous electrolyte according to claim 1 or 2, wherein The nonaqueous electrolyte further includes an electrolyte.

13. The nonaqueous electrolyte according to claim 12, wherein The electrolyte includes an alkali metal salt electrolyte.

14. The nonaqueous electrolyte according to claim 12, wherein The electrolyte includes a lithium salt or a sodium salt.

15. The nonaqueous electrolyte according to claim 14, wherein The lithium salt includes one or more selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonimide, and lithium bis-trifluoromethanesulfonimide, and the sodium salt includes one or more selected from the group consisting of sodium hexafluorophosphate, sodium difluoro oxalate borate, sodium perchlorate, sodium bisfluorosulfonimide, sodium bis-trifluoromethanesulfonimide, and sodium trifluoromethanesulfonate.

16. The nonaqueous electrolyte according to claim 1 or 2, wherein The nonaqueous electrolyte further includes a nonaqueous solvent.

17. The nonaqueous electrolyte according to claim 16, wherein The nonaqueous solvent includes any one or more of the group consisting of cyclic carbonates, chain carbonates, nitrile solvents, ketone solvents, and sulfone solvents.

18. The nonaqueous electrolyte of claim 16, wherein, The nonaqueous solvent includes one or more of the group consisting of ethylene carbonate, propylene carbonate, methyl ethyl 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, butyrosulfone, dimethyl sulfone, methyl ethyl sulfone, diethyl sulfone, tetrahydrofuran, ethylene glycol dimethyl ether, dioxolane, acetone, acetonitrile, and butyronitrile.

19. The nonaqueous electrolyte according to claim 1 or 2, wherein The additive further includes one or more of a sulfonic acid lactone compound.

20. A secondary battery comprising a positive electrode sheet, an electrolytic solution, a separator, and a negative electrode sheet, wherein, The electrolyte is the nonaqueous electrolyte according to any one of claims 1 to 19.

21. An electrically powered device comprising a secondary battery, wherein The secondary battery includes the secondary battery according to claim 20.

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