Non-aqueous electrolyte for improving fast-charging capability, secondary battery, and electric device

Abstract

A non-aqueous electrolyte for improving fast-charging capability, a secondary battery, and an electric device. The non-aqueous electrolyte comprises an organic solvent and an additive; the organic solvent comprises a first organic solvent, and the first organic solvent is a linear carboxylic acid ester; and the additive comprises a first additive, and the first additive is a cyclic organic base additive. By using the cyclic organic base additive in combination with the linear carboxylic acid ester solvent, good cycle performance and storage performance of batteries can be ensured, while the effect of the linear carboxylic acid ester solvent on improving the conductivity of electrolytes can be fully exerted, and gas generation during storage is reduced.

Description

Non-aqueous electrolyte, secondary battery and power device for improving fast charging capability

[0001] Cross-reference to related applications

[0002] This application is based on and claims priority to CN application No. 202410877363.7, filed on July 2, 2024, the contents of which are incorporated herein in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of batteries, in particular to a non-aqueous electrolyte, a secondary battery and a power device. BACKGROUND

[0004] Lithium ion batteries have become the most popular energy storage system due to their high operating potential, long service life and environmental friendliness, and have been widely used in pure electric vehicles, hybrid electric vehicles, smart grids and other fields. At the same time, with the rapid development of new energy vehicles in recent years, the market has also put forward higher demands on the service life and capacity of lithium ion batteries.

[0005] The electrolyte, as an important component of lithium ion batteries, plays an irreplaceable role in improving the fast charging, cycling and safety performance of lithium ion batteries. Compared with carbonates, linear carboxylate has a lower freezing point and smaller viscosity, which can significantly enhance the conductivity of the battery and improve the low-temperature performance and cycle stability of the battery. However, the interface stability of carboxylate with the negative electrode is poor, and the alpha-H on the carboxylate is easy to consume active lithium by getting electrons at the negative electrode, while the negative electrode interface is damaged, causing the decomposition of SEI and deteriorating the performance of the battery. SUMMARY

[0006] In view of the problems in the background art, the purpose of the present application is to provide an electrolyte. The present application can effectively remove acidic impurities in linear carboxylate electrolyte by introducing an organic base additive, reduce the damage to the negative electrode interface, and realize long service life of the battery.

[0007] The present application provides a non-aqueous electrolyte, a secondary battery and a power device to solve the above problems.

[0008] The first aspect of the present application provides a non-aqueous electrolyte, which comprises an organic solvent and an additive, wherein the organic solvent comprises a first organic solvent, and the first organic solvent is a linear carboxylate; and the additive comprises a first additive, and the first additive is a cyclic organic base additive.

[0009] The present application reduces the viscosity of the electrolyte by introducing linear carboxylic acid esters, thereby improving the conductivity of the battery cell and facilitating the improvement of the fast charging capability of the battery cell. However, the compatibility of carboxylic acid esters with the negative electrode is poor, and the alpha-H on the carboxylic acid ester is easy to consume active lithium by electron at the negative electrode, which deteriorates the performance of the battery cell. To solve this problem, the inventors introduce an organic base additive into the electrolyte to capture protons, thereby removing acidic impurities in the electrolyte, reducing the damage to the negative electrode interface, and achieving long service life of the battery cell.

[0010] In some embodiments, the cyclic organic base is an aromatic ring organic base or a non-aromatic ring organic base (e.g., a saturated or unsaturated non-aromatic ring organic base). In some embodiments, the cyclic organic base is a monocyclic or fused bicyclic ring containing 5-12 ring atoms.

[0011] In some embodiments, the cyclic organic base additive includes any one or more of compound 1 represented by general formula (I), compound 2 represented by general formula (II), compound 3 represented by general formula (IV), compound 4 represented by general formula (IV) or general formula (V), and compound 5 represented by general formula (V).

[0012] In general formula (I), Y 1 , Y 2 are the same or different, Y 1 , Y 2 are each independently selected from CH, N; R 11 , R 12 , R 13 are each independently selected from the following groups: H, C1-C6 alkyl, C2-C6 alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g., propargyl (-CH2C≡CH)), halogen (e.g., F, Cl, Br, or I), -R 14 OH, -R 15 NR 16 R 17 , -R 18 -O-R 19 , C3-C5 cycloalkyl, wherein R 14 , R 15 , R 18 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 16 , R 17 , R 19 are each independently selected from hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl, and as R 16 , R 17 , R 19any carbon atom in the C1-C6 alkyl group is optionally substituted with one or more heteroatoms, which are N atoms, S atoms, or P atoms, optionally R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen-containing heterocyclic ring;

[0013] In general formula (III), W 1 and W 2 are the same or different, W 1 is selected from C, N, O, S, W 2 is selected from C, N, and W 1 and W 2 at least one of which is N; R 21 , R 22 , R 23 , R 24 are each independently selected from the following groups: H, C1-C6 alkyl, C2-C6 alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g., propargyl (-CH2C≡CH)), halogen (e.g., F, Cl, Br, or I), -R 25 OH, -R 26 N R 27 R 28 , -R 29 -O-R 30 , C3-C5 cycloalkyl, wherein R 25 , R 26 , R 29 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 27 , R 28 , R 30 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group;

[0014] In general formula (IV), A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 may be the same or different, and are each independently C or N, and at least one (e.g., 1, 2, 3, or 4) of A 1 , A 2 , A 3 , A 4 and A 5 is N; R 31 , R 32 , R 33 , R34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl (e.g. allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g. propargyl (-CH2CºCH)), halogen (e.g. F, Cl, Br or I), -OH, -R 38 NR 39 R 40 , C1-C6 alkoxy, C3-C5 cycloalkyl, wherein R 38 is absent or selected from C1-C6 alkylene, C2-C6 alkenylene, R 39 , R 40 each independently is selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl;

[0015] In general formula (V), X 1 , X 2 , X 3 each independently is C or N, and at least one of X 1 , X 2 , X 3 is N, in general formula (V’), X 1 , X 3 each independently is C or N, and at least one of X 1 , X 3 is N,

[0016] In general formula (V) and (V’), a, b each independently is selected from 0, 1, 2, 3, c is selected from 1, 2, 3, 4, 5, 6, 7, 8, each R 41 each independently is selected from H, C1-C6 alkyl, C2-C6 alkenyl (e.g. allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g. propargyl (-CH2CºCH)), halogen (e.g. F, Cl, Br or I), -R 42 OH, -R 43 NR 44 R 45 , -R 46 -O-R 47 , C1-C6 alkoxy, C3-C5 cycloalkyl, wherein R 42 , R 43 , R 46 each independently is selected from the group consisting of absent, C1-C6 alkylene, C2-C6 alkenylene, R 44 , R 45 , R 47each independently selected from the group consisting of hydrogen, halogen, C1-C6alkyl, C1-C6haloalkyl;

[0017] In general formula (VI), V 1 , V 2 , V 3 each independently is C or N, and at least one of V 1 , V 2 , V 3 at least one of V is N, d is selected from 0, 1, 2, 3, e is selected from 1, 2, 3, 4, 5, 6, each R 51 each independently is selected from the group consisting of H, C1-C6alkyl, C2-C6alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6alkynyl (e.g., propargyl (-CH2CºCH)), halogen (e.g., F, Cl, Br, or I), -R 52 OH, -R 53 N R 54 R 55 , -R 56 -O-R 57 , C3-C5cycloalkyl, wherein R 52 , R 53 , R 56 each independently is selected from the group consisting of: nothing, C1-C6alkylene, C2-C6alkenylene, R 54 , R 55 , R 57 each independently is selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6alkyl, C1-C6haloalkyl.

[0018] In some embodiments, in general formula (II), Y 1 , Y 2 are both N, or, Y 1 , Y 2 one is N and the other is CH.

[0019] In some embodiments, in general formula (II), the R 11 , R 12 , R 13 each independently is selected from the group consisting of hydrogen, halogen, C1-C4alkyl, C3-C5alkenyl, C3-C5alkynyl, -R 14 OH, -R 15 N R 16 R 17 , -R 18 -O-R 19 , wherein R 14 , R 15 , R 18 each independently is selected from the group consisting of: nothing, C1-C3alkylene, R 16 , R17 19 each independently is selected from hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl, and as the R 16 17 19 Any carbon atom in the C1-C3 alkyl group of R 16 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen-containing heterocycle.

[0020] In some embodiments, in general formula (II), the R 11 12 13 each independently is selected from hydrogen, halogen, methyl, ethyl, n-propyl, i-propyl, t-butyl, allyl, propargyl, -OH, -CH2OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3, In some embodiments, the R 11 12 13 each independently is selected from hydrogen, fluorine, methyl, t-butyl, -CH2OH, -CH2NH2, -N(CH3)2, -O-CH3, any one of the following:

[0021] In some embodiments, the compound having the structure according to general formula (II) is selected from any one or more of the following compounds:

[0022] In some embodiments, in general formula (III), W 1 and W 2 are both N, or one of W 1 , W 2 is N and the other is CH.

[0023] In some embodiments, in general formula (III), the R 21 22 23 24 each independently is selected from hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 25 OH, -R 26 NR 27 R 28 , -R 29 -O-R 30 , C3-C5 cycloalkyl, wherein R 25 , R 26 , R​​​​​​​​​​​29 each independently selected from the group consisting of: absent, C1-C4alkylene, R 27 , R 28 , R 30 each independently selected from the group consisting of hydrogen, halogen, C1-C4alkyl, C1-C4haloalkyl.

[0024] In some embodiments, in general formula (III), the R 21 , R 22 , R 23 , R 24 each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, propyl, cyclopropyl, allyl, propargyl, -OH, -CH3OH, -NH2, -NHCH3, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, the R 21 , R 22 , R 23 , R 24 each independently selected from the group consisting of hydrogen, fluorine, methyl, cyclopropyl, allyl, -CH3OH, -NHCH3.

[0025] In some embodiments, the compound having the structure according to general formula (III) is selected from any one or more of the following compounds:

[0026] In some embodiments, in general formula (IV), A 1 is N, A 2 , A 3 , A 4 , A 5 , A 6 , A 7 each independently is C or N. In some embodiments, A 1 is N, and A 5 is C.

[0027] In some embodiments, in general formula (IV), the R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of hydrogen, C1-C4alkyl, C2-C4alkenyl, C2-C4alkynyl, -OH, -R 38 NR 39 R 40 , C1-C4alkoxy, R 38 is absent or is selected from C1-C3alkylene, R 39 , R 40each independently selected from hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl. In some embodiments, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently selected from hydrogen, methyl, ethyl, allyl, propargyl, -OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently selected from hydrogen, methyl, -O-CH3.

[0028] In some embodiments, in general formula (IV), R 32 , R 33 , R 34 , R 35 , R 36 , R 37 are each hydrogen. In some embodiments, R 31 is selected from hydrogen, methyl, ethyl, allyl, propargyl, -OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, R 31 is selected from hydrogen, methyl, -O-CH3.

[0029] In some embodiments, the compound having a structure according to general formula (IV) is selected from any one or more of the following compounds:

[0030] In some embodiments, in general formula (V), X 1 is N, X 2 , X 3 are each independently C or N. In some embodiments, X 2 is N. In some embodiments, X 3 is C. In some embodiments, X 1 , X 3 are each N.

[0031] In some embodiments, in general formula (V), a, b, c are each independently 1, 2, or 3. In some embodiments, a is 2. In some embodiments, b is 1, 2, or 3. In some embodiments, c is 1 or 2.

[0032] In some embodiments, in the general formula (V), a is 0 or 1, and c is 1 or 2.

[0033] In some embodiments, the general formula (V) is (V-1):

[0034] wherein a, b, X 1 , X 2 , X 3 are as defined above.

[0035] In some embodiments, the general formula (V) is (V-1):

[0036] wherein a, X 1 , X 3 are as defined above.

[0037] In some embodiments, in the general formula (V), (V), (V-1), or (V-1), each R 41 is independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 42 OH, -R 43 NR 44 R 45 , -R 46 -O-R 47 , R 42 , R 43 , R 46 is independently selected from the group consisting of nothing, C1-C3 alkylene, R 44 , R 45 , R 47 is independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. In some embodiments, each R 41 is independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, hydroxyl, -NH2, -N(CH3)2. In some embodiments, each R 41 is independently selected from the group consisting of hydrogen, methyl, -N(CH3)2.

[0038] In some embodiments, the compound having the structure of the general formula (V) is selected from any one or more of the following compounds:

[0039] In some embodiments, in the general formula (VI), d is 0 or 1.

[0040] In some embodiments, in the general formula (VI), each R 51 is independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 52OH, -R 53 NR 54 R 55 , -R 56 -O-R 57 , wherein R 52 , R 53 , R 56 are each independently selected from the group consisting of: nothing, C1-C3 alkylene, R 54 , R 55 , R 57 are each independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. In some embodiments, each R 51 are each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, hydroxyl, -NH2, -N(CH3)2. In some embodiments, each R 51 are each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, i-propyl, t-butyl.

[0041] In some embodiments, the compound having the structure of Formula (VI) is selected from any one or more of the following compounds:

[0042] In some embodiments, the first additive has a mass percentage of W2 in the non-aqueous electrolyte, W2 satisfies 0.1%≤W2≤10%, optionally 0.1%≤W2≤5%, further optionally 0.5%≤W2≤3%. W2 within the above range is conducive to reducing the gas production while ensuring the fast charging performance, and improving the cycle performance and storage performance of the battery.

[0043] In some embodiments, W2 is 0.05%~0.1%, 0.1%~0.2%, 0.2%~0.5%, 0.5%~1%, 1%~2%, 2%~5%, 5%~10%, or 10%~12%.

[0044] In some embodiments, the linear carboxylic acid ester is selected from one or more of the compounds of Formula (I),

[0045] wherein R1and R2are each independently selected from C1-C6 alkyl, C1-C6 haloalkyl.

[0046] In some embodiments, R1and R2are each independently selected from C1-C3 alkyl, C1-C3 haloalkyl.

[0047] In some embodiments, R1and R2are each independently selected from methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl.

[0048] In some embodiments, the linear carboxylic acid ester is selected from one or more of the following compounds:

[0049] In some embodiments, the linear carboxylic acid ester is selected from one or more of the following compounds:

[0050] The selection of a suitable linear carboxylic acid ester can keep the viscosity of the electrolyte within a suitable range, thereby making the electrolyte have higher conductivity and the battery have better rapid charging performance.

[0051] In some embodiments, the mass percentage of the first organic solvent is W1 based on the total mass of the organic solvent, and W1 satisfies 20%≤W1≤80%; optionally, W1 satisfies 30%≤W1≤70%. Controlling the mass percentage of the first organic solvent within a suitable range can improve the rapid charging performance of the battery while making the battery have good cycle performance and storage performance.

[0052] In some embodiments, the non-aqueous electrolyte of the present application further comprises a second organic solvent, and optionally, the second organic solvent comprises one or more of a cyclic carbonate or a chain carbonate, and optionally, the second organic solvent is selected from ethylene carbonate (EC), methyl ethyl carbonate (EMC), or a combination thereof. The selection of the second organic solvent can make the battery have better rapid charging performance.

[0053] In some embodiments, the non-aqueous electrolyte of the present application further comprises a second additive, and optionally, the second additive comprises one or more of a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive capable of improving the performance of the battery.

[0054] The second aspect of the present application provides a secondary battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte, wherein the electrolyte is the non-aqueous electrolyte provided by any of the embodiments of the first aspect.

[0055] In some embodiments, the negative electrode active material has a BET specific surface area of 0.5m 2 / g to 2.0m 2 / g; optionally, the negative electrode active material has a BET specific surface area of 0.8m 2 / g to 1.5m 2The BET specific surface area of the negative active material is within the above range, which on the one hand can ensure the acceptance of lithium by the negative active material during charging, reduce the precipitation of lithium on the surface of the negative electrode, and maintain the stability of the battery, and on the other hand can avoid the reaction between the negative electrode and the electrolyte from being too intense, reduce the accumulation of by-products on the surface of the battery, and reduce the impedance of the negative electrode.

[0056] In some embodiments, the porosity of the negative active material coating in the negative electrode tab is P, and P satisfies 20%≤P≤60%; optionally, P satisfies 25%≤P≤45%. The porosity of the negative active material coating is within the above range, which on the one hand can avoid the reduction of the actual use compaction density of the tab due to excessive tab rebound, avoid the impact on the energy density of the battery, and on the other hand can make the particles in the tab have sufficient pores, so that the electrolyte is well infiltrated, the liquid phase diffusion rate is reduced, polarization is reduced, the cycle performance of the battery is improved, and in high-rate charging, ions are more easily reduced, thereby avoiding the formation of metal dendrites and improving the ability of fast charging.

[0057] In some embodiments, the unit area coating weight of the negative electrode tab is CW, and CW satisfies 7 mg / cm 2 ≤CW≤15 mg / cm 2 ; optionally, CW satisfies 9 mg / cm 2 ≤CW≤13 mg / cm 2 . The smaller the unit area coating weight of the negative electrode tab, the better the kinetic performance of the battery, but at the same time, the energy density of the battery will also be lower. CW is within the above range, which can not affect the energy density of the battery under the condition that the battery has good kinetics.

[0058] The third aspect of the present application provides a power utilization device comprising a secondary battery, and the secondary battery comprises any embodiment of the secondary battery provided by the second aspect. BRIEF DESCRIPTION OF DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required 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 creative labor on the basis of the drawings.

[0060] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0061] FIG. 2 is an exploded view of the secondary battery according to an embodiment of the present application shown in FIG. 1.

[0062] FIG. 3 is a schematic diagram of a battery module according to an embodiment of the present application.

[0063] FIG. 4 is a schematic view of a battery pack according to an embodiment of the present application.

[0064] FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4.

[0065] FIG. 6 is a schematic view of an electric device using a secondary battery as a power source according to an embodiment of the present application.

[0066] In the drawings, the drawings are not drawn to scale.

[0067] BRIEF DESCRIPTION OF DRAWINGS 1: battery pack; 2: upper case; 3: lower case; 4: battery module; 5: secondary battery cell; 51: case; 52: electrode assembly; 53: top cap assembly. DETAILED DESCRIPTION

[0068] Embodiments of the present application will be described in further detail below with reference to the accompanying drawings and examples. The detailed description of the following examples and the accompanying drawings are intended to illustrate the principles of the present application by way of example only and are not intended to limit the scope of the present application, i.e., the present application is not limited to the described examples.

[0069] Hereinafter, embodiments of the non-aqueous electrolyte solution, secondary battery, and electric device of the present application are specifically disclosed with appropriate reference to the accompanying drawings. However, there are cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of matters well known in the art, repetitive descriptions 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 drawings and the following description are provided so that those skilled in the art can fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0070] The ranges disclosed herein are intended to be "open" ranges, i.e., the upper and lower limits of the range are not included. The ranges can be "closed" ranges, i.e., the upper and lower limits of the range are included. The ranges can be arbitrarily combined, i.e., any upper limit can be combined with any lower limit to form a range. For example, if a range of 60-120 and a range of 80-110 are listed, it is understood that a range of 60-110 and a range of 80-120 are also contemplated. Furthermore, if a minimum range value of 1 and 2 are listed, and if a maximum range value of 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, the use of "a" and "an" to describe a single item can be taken to also mean "at least one" unless otherwise noted. For example, the phrase "an element" can mean at least one element.

[0071] Unless otherwise indicated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0072] Unless otherwise indicated, all technical features of the present application and optional technical features can be combined with each other to form new technical solutions.

[0073] Unless otherwise indicated, 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), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can also comprise step (c), which 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.

[0074] Unless otherwise indicated, the "includes" and "contains" mentioned in the present application are open-ended. For example, the "includes" and "contains" can mean that other components not listed can also be included or contained.

[0075] The term "or" is inclusive in this application, unless otherwise indicated. So, for example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0076] The term "linear carboxylic acid ester" refers to a straight chain or branched organic compound containing an -0-C(=0)- group.

[0077] The term "cyclic organic base" refers to a basic compound having a cyclic structure composed of one or more nitrogen atoms and carbon atoms.

[0078] The term "alkyl" denotes a straight chain or branched hydrocarbon group, with the removal of one hydrogen atom, for example "C 1-20 The term "alkyl", "C 1-10 The term "alkyl", "C 1-6 The term "alkyl", "C 1-4 The term "alkyl", "C 1-3 The term "alkyl", "C

[0079] The term "alkylene" refers to a divalent straight chain or branched alkane group, consisting only of carbon and hydrogen atoms, containing no degree of unsaturation, and connected to other fragments by two single bonds, including (but not limited to) methylene, The term "alkylene", "C 1-6 The term "alkylene", "C

[0080] The term "alkenyl" refers to a straight chain or branched hydrocarbon group containing at least one carbon-carbon double bond, including for example "C 2-6 The term "alkenyl", "C 2-4 The term "alkenyl", "C

[0081] The term "alkylene" refers to a divalent straight or branched chain alkyl group consisting solely of carbon and hydrogen atoms, containing no unsaturation, and being connected to the rest of the molecule by two single bonds. Examples include, but are not limited to, methylene, ethylene, n-propylene, i-propylene, n-butylene, i-butylene, sec-butylene, t-butylene, n-pentylene, i-pentylene, n-hexylene, and the like. The term "alkenylene" refers to a divalent straight or branched chain alkyl group consisting solely of carbon and hydrogen atoms, containing at least one double bond, and being connected to the rest of the molecule by two single bonds. Examples include, but are not limited to, ethenylene, propenylene, and the like. For example, "C2-6 alkenylene" refers to a divalent straight or branched chain hydrocarbon group containing 2 to 6 carbon atoms and having at least 1 carbon-carbon double bond (>C=C<).

[0082] The term "alkynyl" refers to a straight or branched chain hydrocarbon group containing at least one carbon-carbon triple bond. Examples include, but are not limited to, "C2-6 alkynyl", "C2-6 alkynyl", "C2-6 alkynyl", and the like. Examples include, but are not limited to, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 1,3-butadiynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 1,3-pentadiynyl, 1,4-pentadiynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 1,4-hexadiynyl, and the like. 2- 4-6 The term "alkynyl" refers to a straight or branched chain hydrocarbon group containing at least one carbon-carbon triple bond. Examples include, but are not limited to, "C2-6 alkynyl", "C2-6 alkynyl", "C2-6 alkynyl", and the like. Examples include, but are not limited to, ethynyl, 1-propynyl, 2-propynyl, 1-butynyl, 2-butynyl, 1,3-butadiynyl, 1-pentynyl, 2-pentynyl, 3-pentynyl, 1,3-pentadiynyl, 1,4-pentadiynyl, 1-hexynyl, 2-hexynyl, 3-hexynyl, 1,4-hexadiynyl, and the like.

[0083] The term "heterocyclyl" or "heterocycle" refers to a saturated or partially saturated, monocyclic or polycyclic (such as bicyclic) non-aromatic ring structure whose ring atoms are composed of carbon atoms and at least one (e.g., 1, 2, or 3) heteroatom selected from nitrogen, oxygen, and sulfur. The heterocyclyl group can be attached to the rest of the molecule through any one of the ring atoms, if valence requirements permit. The term "5-6 membered nitrogen-containing heterocycle" as used in the present invention refers to a heterocycle having 5 to 6 ring atoms, at least one (e.g., 1, 2, or 3) of which is a nitrogen atom. Common heterocyclyl groups include, but are not limited to, azetidinyl, oxetanyl, tetrahydrofuryl, pyrrolidinyl, pyrrolidinonyl, imidazolidinyl, pyrazolidinyl, tetrahydropyranyl, piperidinyl, piperazinyl, morpholinyl. The heterocyclyl group in the present invention can be optionally fused to one or more aromatic or non-aromatic rings.

[0084] ​The term "cycloalkyl" refers to a monocyclic or polycyclic group containing saturated or partially unsaturated (e.g., containing one or two double bonds). "Monocyclic alkyl" is preferably a 3-10 member monocyclic alkyl group, more preferably a 3-8 member monocyclic alkyl group, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, and cyclohexenyl. "Polycyclic alkyl" includes "bridged cycloalkyl," "phencyclic alkyl," and "spirocyclic alkyl." A "bridged cycloalkyl" group refers to a monocyclic alkyl group in which any two non-adjacent carbon atoms are connected by an alkylene bridge formed by one or more (e.g., 1-3) additional carbon atoms (i.e., -(CH2)). t - A bridging group in the form of a cycloalkyl group, where t is, for example, 1, 2, or 3. "Faracycloalkyl" comprises a cycloalkyl ring fused to a phenyl, monocycloalkyl, monocycloheterocycloalkyl, or monocycloheteroaryl group. "Spirocycloalkyl" refers to a bicyclic group formed by two cycloalkyl groups sharing a single carbon atom. Polycycloalkyl groups can be 5-18 quinones, preferably 6-15 quinones, more preferably 6-12 quinones. The polycycloalkyl group is preferably a bicycloalkyl group.

[0085] The term "aromatic ring" includes all-carbon monocyclic rings with conjugated π-electron systems as well as heteroaromatic rings. The term "heteroaromatic ring" refers to a monocyclic or polycyclic aromatic ring system having, for example, 5, 6, 7, 8, 9, 10, 11, 12, 13, or 14 ring atoms, particularly 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms, and containing one or more (e.g., 1, 2, 3, or 4) heteroatoms (e.g., oxygen, nitrogen, or sulfur), which may be the same or different.

[0086] The term "alkoxy" refers to a group having an "alkyl-O-" structure, where alkyl is defined as described above. For example, C 1-6 Alkoxy, C 1-4 Alkoxy, C 1-3 Alkoxy or C 1-2 Alkoxy groups, etc. Common alkoxy groups include (but are not limited to) methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, pentoxy, hexoxy, etc. The alkoxy groups in this invention are optionally substituted by one or more substituents described in this invention.

[0087] The term "halogenated" or "halogenated" is defined as including F, Cl, Br, or I.

[0088] The term "substitution" refers to the replacement of one or more (e.g., 1, 2, 3, 4, or 5) hydrogen atoms on a specified compound or structural segment by a substituent, provided that the substitution does not exceed the normal valence of the specified atom in the present case and the substitution forms a stable compound. Combinations of substituents and / or variables are permitted only if such combinations form a stable compound.

[0089] As used herein, the term "one or more" means 1 or more than 1, for example 2, 3, 4, 5, or 10, under reasonable conditions.

[0090] The term "independently" means that at least two groups (or ring systems) in a structure, which have the same or similar range of values, can have the same or different meanings in a particular situation. For example, substituent X and substituent Y are each independently hydrogen, halogen, hydroxyl, cyano, alkyl, or aryl, then when substituent X is hydrogen, substituent Y can be either hydrogen or halogen, hydroxyl, cyano, alkyl, or aryl; similarly, when substituent Y is hydrogen, substituent X can be either hydrogen or halogen, hydroxyl, cyano, alkyl, or aryl.

[0091] Unless specified, as used herein, the point of attachment of a substituent can be from any suitable position of the substituent.

[0092] As described in the background, the conventional method of reinforcing SEI by additives is difficult to meet the higher cycle storage life requirement. In order to solve this problem, the present application provides a non-aqueous electrolyte, a secondary battery and a power utilization device.

[0093] [Non-aqueous electrolyte]

[0094] The first embodiment of the present application provides a non-aqueous electrolyte, the non-aqueous electrolyte comprising an organic solvent and an additive, the organic solvent comprising a first organic solvent, the first organic solvent being a linear carboxylic acid ester; the additive comprising a first additive, the first additive being a cyclic organic base type additive.

[0095] The present application reduces the viscosity of the electrolyte by introducing a linear carboxylic acid ester, thereby improving the conductivity of the battery cell, which is beneficial to the improvement of the fast charging capability of the battery cell. However, the compatibility of carboxylic acid ester with the negative electrode is poor, and the α-H on the carboxylic acid ester is easy to consume active lithium by electron at the negative electrode, which deteriorates the performance of the battery cell. To solve this problem, the inventors introduce a proton-capturing organic base type additive into the electrolyte, which removes acidic impurities in the electrolyte and reduces the damage to the negative electrode interface, thereby realizing long life of the battery cell.

[0096] The cyclic organic base type additive that can be used in the present application can be an aromatic ring organic base or a non-aromatic ring organic base (for example, a saturated or unsaturated non-aromatic ring organic base). Exemplary aromatic ring organic bases can be seen in compounds represented by general formula (II), (III), or (IV). Exemplary saturated non-aromatic ring organic bases can be seen in compounds represented by general formula (VI). Exemplary unsaturated non-aromatic ring organic bases can be seen in compounds represented by general formula (V) or (V’).

[0097] In some embodiments, the cyclic organic base is a monocyclic or fused bicyclic ring containing 5-12 (e.g., 5, 6, 7, 8, 9, 10, 11, or 12) ring atoms. In some embodiments, the cyclic organic base is a nitrogen-containing heteroaromatic monocyclic ring, a nitrogen-containing saturated monocyclic heterocycle, or a nitrogen-containing unsaturated monocyclic heterocycle containing 5, 6, 7, or 8 ring atoms. In some embodiments, the cyclic organic base is a nitrogen-containing heteroaromatic fused bicyclic ring, a nitrogen-containing saturated fused heterocycle, or a nitrogen-containing unsaturated fused heterocycle containing 7, 8, 9, 10, 11, or 12 ring atoms.

[0098] The present application employs cyclic organic bases as electrolyte additives. Compared with acyclic organic bases, the alkyl groups on the heteroatoms of the cyclic organic bases have smaller bond angles due to the effect of the ring, fully exposing the lone pair of electrons on the heteroatoms, so the heteroatoms generally have stronger nucleophilic ability and stronger ability to capture free protons in the electrolyte, reducing the damage of SEI to the negative electrode. In some embodiments, the cyclic organic base additive includes any one or more of compound 1 represented by general formula (I), compound 2 represented by general formula (II), compound 3 represented by general formula (IV), compound 4 represented by general formula (IV) or general formula (V), and compound 5 represented by general formula (V),

[0099] In general formula (I), Y 1 , Y 2 are the same or different, Y 1 , Y 2 are each independently selected from CH, N; R 11 , R 12 , R 13 are each independently selected from the following groups: H, C1-C6 alkyl, C2-C6 alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g., propargyl (-CH2C≡CH)), halogen (e.g., F, Cl, Br, or I), -R 14 OH, -R 15 NR 16 R 17 , -R 18 -O-R 19 , C3-C5 cycloalkyl, wherein R 14 , R 15 , R 18 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 16 , R 17 , R 19 are each independently selected from hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl, and as R 16 , R 17 , R 19any carbon atom in the C1-C6 alkyl group is optionally substituted with one or more heteroatoms, which are N atoms, S atoms, or P atoms, optionally R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen-containing heterocyclic ring;

[0100] In general formula (III), W 1 and W 2 are the same or different, W 1 is selected from C, N, O, S, W 2 is selected from C, N, and at least one of W1and W2is N; R 21 , R 22 , R 23 , R 24 are each independently selected from the following groups: H, C1-C6 alkyl, C2-C6 alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g., propargyl (-CH2CºCH)), halogen (e.g., F, Cl, Br, or I), -R 25 OH, -R 26 N R 27 R 28 , -R 29 -O-R 30 , C3-C5 cycloalkyl, wherein R 25 , R 26 , R 29 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 27 , R 28 , R 30 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group;

[0101] In general formula (IV), A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 may be the same or different, and are each independently C or N, and at least one (e.g., 1, 2, 3, or 4) of A1, A2, A3, A4, and A5is N; R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37each independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl (e.g. allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g. propargyl (-CH2CºCH)), halogen (e.g. F, CI, Br or I), -OH, -R 38 NR 39 R 40 , C1-C6 alkoxy, C3-C5 cycloalkyl, wherein R 38 is absent or selected from C1-C6 alkylene, C2-C6 alkenylene, R 39 , R 40 each independently selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl;

[0102] In general formula (V), X 1 , X 2 , X 3 each independently is C or N, and at least one of X 1 , X 2 , X 3 is N, in general formula (V’), X 1 , X 3 each independently is C or N, and at least one of X 1 , X 3 is N,

[0103] In general formula (V) and (V’), a, b are each independently selected from 0, 1, 2, 3, c is selected from 1, 2, 3, 4, 5, 6, 7, 8, each R 41 each independently selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl (e.g. allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g. propargyl (-CH2CºCH)), halogen (e.g. F, CI, Br or I), -R 42 OH, -R 43 NR 44 R 45 , -R 46 -O-R 47 , C3-C5 cycloalkyl, wherein R 42 , R 43 , R 46 each independently selected from the group consisting of: absent, C1-C6 alkylene, C2-C6 alkenylene, R 44 , R 45 , R 47 each independently selected from the group consisting of hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl;

[0104] In general formula (VI), V 1 , V2 , V 3 each independently C or N, and V 1 , V 2 , V 3 at least one of which is N, d is selected from 0, 1, 2, 3, e is selected from 1, 2, 3, 4, 5, 6, each R 51 each independently selected from H, C1-C6 alkyl, C2-C6 alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6 alkynyl (e.g., propargyl (-CH2CºCH)), halogen (e.g., F, Cl, Br, or I), -R 52 OH, -R 53 N R 54 R 55 , -R 56 -O-R 57 , C3-C5 cycloalkyl, wherein R 52 , R 53 , R 56 each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 54 , R 55 , R 57 each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 haloalkyl group.

[0105] In some embodiments, in general formula (II), Y 1 , Y 2 are both N, or, one of Y 1 , Y 2 is N and the other is CH.

[0106] In some embodiments, in general formula (II), the R 11 , R 12 , R 13 each independently selected from hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 14 OH, -R 15 N R 16 R 17 , -R 18 -O-R 19 , wherein R 14 , R 15 , R 18 each independently selected from: nothing, C1-C3 alkylene, R 16 , R 17 , R 19 each independently selected from hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl, and as the R 16 , R 17 , R19 Any of the carbon atoms in the C1-C3 alkyl group can be substituted with one or more heteroatoms, which are N atoms, optionally R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen containing heterocycle.

[0107] In some embodiments, in general formula (II), the R 11 , R 12 , R 13 are each independently selected from the group consisting of hydrogen, halogen, methyl, ethyl, n-propyl, i-propyl, t-butyl, allyl, propargyl, -OH, -CH2OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3, In some embodiments, the R 11 , R 12 , R 13 are each independently selected from the group consisting of hydrogen, fluorine, methyl, t-butyl, -CH2OH, -CH2NH2, -N(CH3)2, -O-CH3, any of the foregoing.

[0108] In some embodiments, the compound having the structure of general formula (II) is selected from any one or more of the following compounds:

[0109] In some embodiments, in general formula (III), W 1 and W 2 are both N, or one of W 1 , W 2 is N and the other is CH.

[0110] In some embodiments, in general formula (III), the R 21 , R 22 , R 23 , R 24 are each independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 25 OH, -R 26 NR 27 R 28 , -R 29 -O-R 30 , C3-C5 cycloalkyl, wherein R 25 , R 26 , R 29 are each independently selected from the group consisting of: nothing, C1-C4 alkylene, R 27 , R 28 , R 30each independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl.

[0111] In some embodiments, in general formula (III), the R 21 , R 22 , R 23 , R 24 each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, propyl, cyclopropyl, allyl, propargyl, -OH, -CH3OH, -NH2, -NHCH3, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, the R 21 , R 22 , R 23 , R 24 each independently selected from the group consisting of hydrogen, fluorine, methyl, cyclopropyl, allyl, -CH3OH, -NHCH3.

[0112] In some embodiments, the compound having a structure according to general formula (III) is selected from any one or more of the following compounds:

[0113] In some embodiments, in general formula (IV), A 1 is N, A 2 , A 3 , A 4 , A 5 , A 6 , A 7 each independently is C or N. In some embodiments, A 1 is N, and A 5 is C.

[0114] In some embodiments, in general formula (IV), R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of hydrogen, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, -OH, -R 38 NR 39 R 40 , C1-C4 alkoxy, R 38 is absent or selected from C1-C3 alkylene, R 39 , R 40 each independently is selected from the group consisting of hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl. In some embodiments, R 31 , R 32 , R 33 , R34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of hydrogen, methyl, ethyl, allyl, propargyl, -OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of hydrogen, methyl, -O-CH3.

[0115] In some embodiments, in general formula (IV), R 32 , R 33 , R 34 , R 35 , R 36 , R 37 are all hydrogen. In some embodiments, R 31 is selected from the group consisting of hydrogen, methyl, ethyl, allyl, propargyl, -OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, R 31 is selected from the group consisting of hydrogen, methyl, -O-CH3.

[0116] In some embodiments, the compound having the structure represented by general formula (IV) is selected from any one or more of the following compounds:

[0117] In some embodiments, in general formula (V), X 1 is N, X 2 , X 3 each independently is C or N. In some embodiments, X 2 is N. In some embodiments, X 3 is C. In some embodiments, X 1 , X 3 are all N.

[0118] In some embodiments, in general formula (V), a, b, c each independently is 1, 2, or 3. In some embodiments, a is 2. In some embodiments, b is 1, 2, or 3. In some embodiments, c is 1 or 2.

[0119] In some embodiments, in general formula (V’), a is 0 or 1, and c is 1 or 2.

[0120] In some embodiments, the general formula (V) is (V-1):

[0121] wherein a, b, X 1 , X 2 , X 3 are as defined above.

[0122] In some embodiments, the general formula (V’) is (V’-1):

[0123] wherein a, X 1 , X 3 are as defined above.

[0124] In some embodiments, in general formula (V), (V’), (V-1), or (V’-1), each R 41 is independently selected from hydrogen, halogen, C1-C4alkyl, C3-C5alkenyl, C3-C5alkynyl, -R 42 OH, -R 43 NR 44 R 45 , -R 46 -O-R 47 , R 42 , R 43 , R 46 is independently selected from: nothing, C1-C3alkylene, R 44 , R 45 , R 47 is independently selected from hydrogen, halogen, C1-C4alkyl, C1-C4haloalkyl. In some embodiments, each R 41 is independently selected from hydrogen, fluorine, methyl, ethyl, hydroxyl, -NH2, -N(CH3)2. In some embodiments, each R 41 is independently selected from hydrogen, methyl, -N(CH3)2.

[0125] In some embodiments, the compound having the structure of general formula (V) is selected from any one or more of the following compounds:

[0126] In some embodiments, in general formula (VI), d is 0 or 1.

[0127] In some embodiments, in general formula (VI), each R 51 is independently selected from hydrogen, halogen, C1-C4alkyl, C3-C5alkenyl, C3-C5alkynyl, -R 52 OH, -R 53 NR 54 R 55 , -R 56 -O-R 57 , R52 R 53 R 56 each independently selected from the group consisting of: nothing, C1-C3 alkylene, R 54 R 55 R 57 each independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. In some embodiments, each R 51 each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, hydroxyl, -NH2, -N(CH3)2. In some embodiments, each R 51 each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, i-propyl, t-butyl.

[0128] In some embodiments, the compound having the structure of general formula (VI) is selected from any one or more of the following compounds:

[0129] In some embodiments, the mass percentage of the first additive in the non-aqueous electrolyte is W2, W2 satisfies 0.1%≤W2≤10%, optionally 0.1%≤W2≤5%, further optionally 0.5%≤W2≤3%. W2 within the above range is conducive to reducing the gas production while ensuring the fast charging performance, and improving the cycle performance and storage performance of the battery.

[0130] In some embodiments, W2 is 0.05%~0.1%, 0.1%~0.2%, 0.2%~0.5%, 0.5%~1%, 1%~2%, 2%~5%, 5%~10% or 10%~12%.

[0131] In some embodiments, the linear carboxylic acid ester is selected from one or more of the compounds of general formula (I),

[0132] wherein R1and R2are each independently selected from C1-C6 alkyl, C1-C6 haloalkyl.

[0133] In some embodiments, the linear carboxylic acid ester is selected from one or more of the following compounds:

[0134] In some embodiments, the linear carboxylic acid ester is selected from one or more of the following compounds:

[0135] Selecting a suitable linear carboxylic acid ester can keep the viscosity of the electrolyte within a suitable range, thereby making the electrolyte have higher electrical conductivity and the battery have better fast charging performance.

[0136] In some embodiments, the mass percentage of the first organic solvent is W1, W1 satisfies 20%≤W1≤80%, based on the total mass of the organic solvent; optionally, W1 satisfies 30%≤W1≤70%. Controlling the mass percentage of the first organic solvent within a suitable range can improve the fast charging performance of the battery while ensuring good cycle performance and storage performance of the battery.

[0137] In some embodiments, W1 is 20%-30%, 30%-40%, 40%-50%, 50%-60%, 60%-70%, or 70%-80%.

[0138] In some embodiments, the organic solvent in the non-aqueous electrolyte of the present application can further include a second organic solvent, which is not particularly limited in type and can be selected according to actual needs. Specifically, the second organic solvent can further include one or more of cyclic carbonates or chain carbonates. The type of chain carbonates or cyclic carbonates is not particularly limited and can be selected according to actual needs.

[0139] In some embodiments, the second organic solvent can include one or more of propylene carbonate (PC), 1,2-butylene carbonate (BC), dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), and ethyl propyl carbonate (EPC). When the organic solvent of the present application further includes these second organic solvents, the battery can have good fast charging performance. In some embodiments, the mass percentage of the second organic solvent is W3, W3 satisfies 20%≤W3≤80%, based on the total mass of the organic solvent. In some embodiments, W3 is 40%-50%, 50%-60%, 60%-70%, or 70%-80%. In some embodiments, the second organic solvent is a combination of EC and EMC. In some embodiments, the mass percentage of EC and EMC is 30%:(10%-40%).

[0140] In some embodiments, the non-aqueous electrolyte of the present application can further comprise a second additive. As an example, the second additive can comprise a negative electrode film-forming additive, a positive electrode film-forming additive, and can further comprise an additive capable of improving certain properties of the battery, such as an additive capable of improving overcharge performance of the battery, an additive capable of improving high-temperature or low-temperature performance of the battery, and the like. In some embodiments, the second additive is selected from at least one of a cyclic carbonate compound containing an unsaturated bond, a halogen-substituted cyclic carbonate compound, a sulfate compound, a sulfite compound, a sulfonic acid lactone compound, a disulfonic acid compound, a nitrile compound, an aromatic compound, an isocyanate compound, a phosphazene compound, a cyclic anhydride compound, a phosphite compound, a phosphate compound, a borate compound, a carboxylate compound.

[0141] In some embodiments, the non-aqueous electrolyte employed in the present application can further comprise an electrolyte. Any electrolyte commonly used in non-aqueous electrolytes can be considered for use in the non-aqueous electrolyte of the present application. One skilled in the art can select an electrolyte based on the battery system in which the non-aqueous electrolyte is to be used, such as by selecting a conventional electrolyte suitable for use in a secondary battery. In some embodiments, the electrolyte comprises an alkali metal salt electrolyte; optionally, the electrolyte comprises a lithium salt; optionally, the lithium salt comprises one or more selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, and lithium bis-trifluoromethanesulfonylimide. Each of the above lithium salts can be used alone or in combination with two or more. In some embodiments, the lithium salt can be selected from LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2), LiPF6, LiBF4, LiBOB, LiAsF6, Li(FSO2)2N, LiCF3SO3, and LiClO4, wherein x and y are natural numbers, and each of m and n is independently a natural number of up to 9.

[0142] The content of the electrolyte in the non-aqueous electrolyte can be the same as that in conventional non-aqueous electrolytes. In some embodiments, the content of the electrolyte in the non-aqueous electrolyte is 0.5 M to 2.5 M, and optionally 0.8 M to 2 M.

[0143] [Secondary battery]

[0144] A secondary battery, also referred to as a rechargeable battery or a storage battery, is a battery that can be used continuously after activation of the active material by charging after discharging of the battery.

[0145] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During charging and discharging of the battery, active ions (e.g., lithium ions) are intercalated and deintercalated between the positive electrode sheet and the negative electrode sheet. The separator is disposed between the positive electrode sheet and the negative electrode sheet, and mainly functions to prevent short circuiting between the positive electrode and the negative electrode, while allowing the active ions to pass through. The electrolyte is disposed between the positive electrode sheet and the negative electrode sheet, and mainly functions to conduct the active ions.

[0146] A second embodiment of the present application provides a secondary battery including a positive electrode sheet, a negative electrode sheet, and an electrolyte, the electrolyte being any one of the nonaqueous electrolytes provided in the first embodiment.

[0147] The present application uses a cyclic organic base additive in combination with a linear carboxylic acid ester solvent, which can fully exert the conductivity-improving effect of the linear carboxylic acid ester solvent on the electrolyte, while ensuring good cycle performance and storage performance of the battery, and reducing gas generation during storage.

[0148] [Negative electrode sheet]

[0149] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material coating layer disposed on at least one surface of the negative electrode current collector, the negative electrode active material coating layer including a negative electrode active material.

[0150] As an example, the negative electrode current collector has two opposite surfaces 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.

[0151] In some embodiments, the negative electrode current collector can be a metal foil or a composite current collector. For example, as the metal foil, a copper foil can be used. 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.).

[0152] 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, mesocarbon microbeads, carbon fiber, carbon nanotube, 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.

[0153] In some embodiments, the negative active material has a BET specific surface area of 0.5 m 2 / g to 2.0 m 2 / g. In some embodiments, the negative active material has a BET specific surface area of 0.8 m 2 / g to 1.5 m 2 / g. The BET specific surface area of the negative active material within the above range can, on the one hand, ensure the acceptance of lithium by the negative active material during charging, reduce the precipitation of lithium on the surface of the negative electrode, and maintain the stability of the battery, and on the other hand, make the contact area between the negative electrode and the electrolyte not too large, avoid the reaction between the two becoming too intense, reduce the accumulation of by-products on the surface of the battery, and reduce the impedance of the negative electrode.

[0154] In some embodiments, the negative active material has a BET specific surface area of 0.2 m 2 / g to 0.5 m 2 / g, 0.5 m 2 / g to 0.7 m 2 / g, 0.7 m 2 / g to 0.8 m 2 / g, 0.8 m 2 / g to 1.5 m 2 / g, 1.5 m 2 / g to 1.8 m 2 / g, or 1.8 m 2 / g to 2.2 m 2 / g.

[0155] Specific surface area generally refers to the specific surface area of a solid material, which is the total surface area per unit mass of the material, and the unit is m 2 / g. In the present application, the specific surface area BET has the meaning known in the art and can be measured by instruments and methods known in the art. For example, reference can be made to the national standard GB / T 19587-2017 "Determination of Specific Surface Area of Solid Substances by Gas Adsorption BET Method".

[0156] In some embodiments, the porosity of the negative active material coating in the negative electrode tab is P, and P satisfies 20%≤P≤60%; optionally, P satisfies 25%≤P≤45%. Considering the liquid phase conduction capacity, the greater the porosity of the negative electrode tab, the better the wettability of the electrolyte, and the higher the liquid phase diffusion speed. In large rate charging, ions are more easily reduced, thereby avoiding the formation of metal dendrites and improving the ability of fast charging. The porosity of the negative active material coating in the above range can avoid the decrease of the actual use compaction density of the tab due to the excessive rebound of the tab, avoid the impact on the energy density of the battery, on the other hand, make the tab have enough pores between the particles, make the electrolyte wettability better, the liquid phase diffusion rate, reduce the polarization, thereby improving the cycle performance of the battery, and in large rate charging, ions are more easily reduced, thereby avoiding the formation of metal dendrites and improving the ability of fast charging.

[0157] In some embodiments, the porosity of the negative active material coating is P, and P satisfies 18%≤P≤20%, 20%≤P≤22%, 22%≤P≤25%, 25%≤P≤28%, 28%≤P≤45%, 45%≤P≤48%, 48%≤P≤60%, or 60%≤P≤62%.

[0158] In the present application, the porosity of the tab is the meaning known in the art, which can be tested according to the national standard GB / T24586-2009 “Determination of apparent density, true density and porosity of iron ore”. The porosity P of the tab=(V-V0) / V×100%, wherein V0 is the true volume of the tab, and V is the apparent volume of the tab.

[0159] In some embodiments, the coating weight per unit area of the negative electrode tab is CW, and CW satisfies 7mg / cm 2 ≤CW≤15mg / cm 2 ; optionally, CW satisfies 9mg / cm 2 ≤CW≤13mg / cm 2 . The smaller the coating weight per unit area of the negative electrode tab, the better the kinetic performance of the battery, but at the same time, the energy density of the battery will also be lower. CW in the above range can have good kinetics of the battery without affecting the energy density of the battery.

[0160] In some embodiments, CW satisfies 6mg / cm 2 ≤CW≤7mg / cm 2 , 7mg / cm 2 ≤CW≤8mg / cm 2 , 8mg / cm 2 ≤CW≤9mg / cm 2 , 9mg / cm 2≤ CW≤ 12 mg / cm 2 , 12 mg / cm 2 ≤ CW≤ 13 mg / cm 2 , 13 mg / cm 2 ≤ CW≤ 14 mg / cm 2 , 14 mg / cm 2 ≤ CW≤ 15 mg / cm 2 or 15 mg / cm 2 ≤ CW≤ 16 mg / cm 2 .

[0161] The following exemplary gives the meaning and test method of the coating weight per unit area of the electrode tab:

[0162] The coating weight per unit area of the electrode tab represents the dry weight of the coating paste per unit area of the current collector surface. It can be measured by the following method: take several pieces of current collector foil, each with an area of S, and weigh each piece separately, and take the average value, denoted as M1; take several pieces of tab coated with the same amount of paste, dry at 120°C for 1 hour after uniform coating, and after detection that the solvent is substantially removed, weigh the dried current collector foil coated with the paste on one side, take the average value, denoted as M2; then the coating weight CW of the active material layer on one side of the current collector is (M2-M1) / S.

[0163] In some embodiments, the negative electrode active material coating layer can also 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).

[0164] In some embodiments, the negative electrode active material coating layer can also 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 dots, carbon nanotubes, graphene, and carbon nanofibers.

[0165] In some embodiments, the negative electrode active material coating layer can also optionally include other auxiliary agents, such as thickening agents (such as sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0166] In some embodiments, the negative electrode tab can be prepared by dispersing the above-mentioned components for preparing the negative electrode tab, such as the negative electrode active material, the conductive agent, the binder, and any other components, in a solvent (such as deionized water) to form a negative electrode paste; coating the negative electrode paste on the negative electrode current collector, and after processes such as drying, cold pressing, and the like, the negative electrode tab can be obtained.

[0167] [Positive electrode tab]

[0168] 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, the positive electrode film layer including a positive electrode active material.

[0169] As an example, the positive electrode current collector has two surfaces opposite in the thickness direction thereof, and the positive electrode film layer is disposed on either one or both of the two opposite surfaces of the positive electrode current collector.

[0170] 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 such as a base material of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0171] 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, when the secondary battery is a lithium ion secondary battery, the positive electrode active material can be selected from materials capable of deintercalating and intercalating lithium ions. The positive electrode active material can include at least one of a lithium-containing phosphate of 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. Among them, 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(also can be referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also can be referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also can be referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also can be referred to as NCM622 LiNi 0.8 Co 0.1 Mn 0.1 O2(also can be referred to as NCM 811 LiNi 0.85 Co 0.15 Al 0.05 O2) and modified compounds thereof. Examples of the olivine-structured lithium-containing phosphate can include, but are not limited to, at least one of lithium iron phosphate (such as LiFePO4(also can be referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (such as LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon. In some embodiments, the positive electrode active material is selected from at least one of LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.9 Co 0.055 Mn 0.055 O2.

[0172] The battery will be accompanied by Li deintercalation and consumption during charging and discharging, and the molar content of Li is different when the battery is discharged to different states. In the enumeration of the positive electrode material in the present application, the molar content of Li is the initial state of the material, i.e., the state before feeding, and the positive electrode material is applied to the battery system. After charging and discharging cycles, the molar content of Li will change.

[0173] In the enumeration of the positive electrode material in the present application, the molar content of O is only the theoretical state value, and the release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will appear to be floating.

[0174] When the secondary battery is a sodium-ion secondary battery, as an example, the positive electrode active material of the sodium-ion secondary battery can include at least one of the following materials: at least one of sodium transition metal oxides, polyanion compounds, and Prussian blue compounds. However, the present application is not limited to these materials, and other conventional and well-known materials that can be used as positive electrode active materials for sodium-ion batteries can also be used.

[0175] As an optional technical solution of the present application, in the sodium transition metal oxide, the transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The sodium transition metal oxide is, for example, Na xMO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr and Cu, and 0 < x < 1.

[0176] As an optional technical solution of the present application, the polyanionic compound can be a compound having sodium ions, transition metal ions and tetrahedral (YO4) n- anion units. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y can be at least one of P, S and Si; and n represents the valence of (YO4) n- .

[0177] The polyanionic compound can also be a compound having sodium ions, transition metal ions, tetrahedral (YO4) n- anion units and halogen anions. The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce; Y can be at least one of P, S and Si, and n represents the valence of (YO4) n- . The halogen can be at least one of F, Cl and Br.

[0178] The polyanionic compound can also be a compound having sodium ions, tetrahedral (YO4) n- anion units, polyhedral units (ZO y ) m+ and optional halogen anions. Y can be at least one of P, S and Si, and n represents the valence of (YO4) n- . Z represents a transition metal, which can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce, and m represents the valence of (ZO y ) m+ . The halogen can be at least one of F, Cl and Br.

[0179] The polyanionic compound can be at least one of NaFePO4, Na3V2(PO4)3(Na3V2P6, NVP for short), Na4Fe3(PO4)2(P2O7), NaM’PO4F (M’ is one or more of V, Fe, Mn and Ni) and Na3(VO y )2(PO4)2F 3-2y (0 < y < 1).

[0180] The Prussian blue compound can be a compound having sodium ions, transition metal ions and cyanide ions (CN-). The transition metal can be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr and Ce. The Prussian blue compound can be, for example,a Me b Me’ c (CN)6, wherein Me and Me’ are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn, 0 < a ≤ 2, 0 < b < 1, and 0 < c < 1.

[0181] 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 acrylate resin.

[0182] 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.

[0183] 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, or the like to obtain the positive electrode tab.

[0184] [Separator]

[0185] In some embodiments, the secondary battery further includes a separator. The type of the separator is not particularly limited in the present application, and any publicly known porous structure separator having good chemical stability and mechanical stability can be used.

[0186] 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 respective layers can be the same or different, and are not particularly limited.

[0187] In some embodiments, the positive electrode tab, the negative electrode tab, and the separator can be used to make an electrode assembly through a winding process or a stacking process.

[0188] In some embodiments, the secondary battery includes a secondary battery cell, or includes a battery module and a battery pack.

[0189] In some embodiments, the secondary battery can include an outer package. The outer package can be used to package the above-mentioned electrode assembly and the electrolyte.

[0190] 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, or the like. 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 plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, or the like can be listed.

[0191] The shape of the secondary battery cell is not particularly limited in the present application, and can be cylindrical, square, or any other shape. For example, FIG. 1 is a square structure of a secondary battery cell 5 as an example.

[0192] In some embodiments, referring to FIG. 2, the outer package can include a shell 51 and a top cover assembly 53. The shell 51 can 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 communicating with the receiving cavity, and the top cover assembly 53 can be provided on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 through 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 cell 5 can be one or more, which can be selected by those skilled in the art according to the specific actual needs.

[0193] In some embodiments, the secondary battery cell can be assembled into a battery module, and the number of secondary battery cells contained in the battery module can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery module.

[0194] FIG. 3 is a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of secondary battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arrangements can also be used. Further, the plurality of secondary battery cells 5 can be fixed by fasteners.

[0195] Optionally, the battery module 4 can also include a housing having a receiving space, and the plurality of secondary battery cells 5 are received in the receiving space.

[0196] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, which can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0197] FIGS. 4 and 5 are a battery pack 1 as an example. Referring to FIGS. 4 and 5, the battery pack 1 can include a battery box and a plurality of battery modules 4 arranged in the battery box. The battery box includes an upper box body 2 and a lower box body 3, and the upper box body 2 can be provided on the lower box body 3 to form a closed space for receiving the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0198] In addition, the application also provides a power utilization device comprising the secondary battery provided by the application. The secondary battery 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.

[0199] As the power utilization device, a secondary battery monomer, a battery module or a battery pack can be selected according to the use requirement thereof.

[0200] FIG. 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 requirement of high power and high energy density of the secondary battery for the power utilization device, a battery pack or a battery module can be used.

[0201] [Embodiment]

[0202] Hereinafter, the embodiments of the application are described. The embodiments described below are exemplary and are only used to explain the application and cannot be understood as a limitation of the application. If the specific technology or condition is not indicated in the embodiments, the technology or condition described in the literature in the art or according to the product instruction is used. If the reagent or instrument is not indicated by the manufacturer, it is a conventional product that can be obtained by market purchase.

[0203] The lithium ion batteries of the comparative examples and the embodiments are prepared according to the following method

[0204] (1) Preparation of the positive electrode sheet

[0205] The positive electrode active material lithium iron phosphate, the binder polyvinylidene fluoride (PVDF) and the conductive agent acetylene black are dissolved in the solvent N-methyl pyrrolidone (NMP) according to the mass ratio of 97:2:1, and after being fully stirred and uniformly mixed, a positive electrode slurry is obtained; then the positive electrode slurry is uniformly coated on the positive electrode current collector, and then dried, cold-pressed and cut to obtain the positive electrode sheet.

[0206] (2) Preparation of the negative electrode sheet

[0207] The active material artificial graphite, the conductive agent acetylene black, the binder styrene butadiene rubber (SBR) and the thickening agent sodium carboxymethyl cellulose (CMC) are dissolved in the solvent deionized water according to the mass ratio of 95:2:2:1, and after being uniformly mixed with the solvent deionized water, a negative electrode slurry is prepared; then the negative electrode slurry is uniformly coated on the negative electrode current collector copper foil, and after being dried, a negative electrode film is obtained, and then cold-pressed and cut to obtain the negative electrode sheet.

[0208] (3) Preparation of electrolyte

[0209] In an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm), compound 1-2, ethylene carbonate (EC), and methyl ethyl carbonate (EMC) were mixed uniformly in a mass ratio of 30:30:40 to prepare an organic solvent; a certain amount of LiPF6 and a certain amount of compound 2-6 were dissolved in the above organic solvent, and stirred uniformly to obtain an electrolyte. The mass percentage of compound 2-6 in the electrolyte was 2%, and the electrolyte was obtained after uniform stirring.

[0210] (4) Preparation of separator film: a conventional polypropylene film was used as the separator film.

[0211] (5) Preparation of lithium ion battery

[0212] The positive electrode sheet, the separator film, and the negative electrode sheet were 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 was placed in a battery shell, dried, and then injected with an electrolyte, and then subjected to processes such as formation and standing to obtain a lithium ion battery. Examples 2-72 and Comparative Examples 1-2

[0213] The preparation method of Examples 2-72 and Comparative Examples 1-2 was similar to that of Example 1, except that the related parameters of the electrolyte were adjusted. The specific electrolyte parameters are shown in Table 1.

[0214] Next, the test methods of the physical parameters and performance parameters mentioned in the examples of the present application are briefly introduced.

[0215] 1. Test method of specific surface area BET

[0216] Specific surface area generally refers to the specific surface area of a solid material, which is the total surface area per unit mass of material, and the unit is m 2 / g. In the present application, the specific surface area BET has the meaning known in the art and can be determined by instruments and methods known in the art. For example, reference can be made to the national standard GB / T 19587-2017 “Determination of Specific Surface Area of Solid Substances by Gas Adsorption BET Method”.

[0217] 2. Test method of porosity of electrode sheet

[0218] The porosity P of the electrode sheet = (V-V0) / V x 100%, wherein V0 is the true volume of the electrode sheet, and V is the apparent volume of the electrode sheet. The porosity of the electrode sheet has the meaning known in the art, and can be tested according to the national standard GB / T24586-2009 “Determination of Apparent Density, True Density and Porosity of Iron Ore”.

[0219] 3. Test method of coating weight per unit area of electrode tab

[0220] The coating weight per unit area of electrode tab represents the dry weight of the coating slurry per unit area of the current collector surface. It can be measured by the following method: take several pieces of current collector foil, each with an area of S, and weigh each piece separately, then take the average value, denoted as M1; take several pieces of tab coated with the same amount of slurry, dry them at 120℃ for 1 hour after uniform coating, and then detect that they are substantially free of solvent, then weigh the dried single-sided coated slurry current collector foil, take the average value, denoted as M2; then the coating weight CW of the single-sided active material layer on the current collector is (M2-M1) / S.

[0221] 4. 45℃ cycle performance test

[0222] At 45℃, the lithium ion battery is charged at 1C constant current to a voltage of 3.65V, then charged at 3.65V constant voltage to a current ≤0.05C, then the battery is discharged at 1C constant current to a voltage of 2V, which is a charge and discharge process, and the discharge capacity at this time is recorded as the discharge capacity of the first cycle of the battery. Repeat the charging and discharging cycles, and calculate the cycle number when the capacity retention rate is 80%.

[0223] The capacity retention rate (%) of the battery after 45℃ cycling N times = (the discharge capacity of the battery in the Nth cycle / the discharge capacity of the battery in the first cycle) x 100%.

[0224] 5. Fast charging time test

[0225] At 25℃, the secondary battery is charged at 0.33C constant current to a charge cut-off voltage of 3.65V, then charged at constant voltage to a current of 0.05C, and then discharged at 0.33C constant current to a discharge cut-off voltage of 2V after 5min, and the actual capacity is recorded as C0.

[0226] Then the secondary battery is sequentially charged at 0.5C0, 1C0, 1.5C0, 2C0, 2.5C0, 3C0, 3.5C0, 4C0, 4.5C0 constant current to the full battery charging cut-off voltage 3.65V or 0V negative electrode cut-off potential (whichever is reached first), after each charging is completed, it needs to be discharged at 1C0 to the full battery discharge cut-off voltage 2V, record the negative electrode potential corresponding to 10%, 20%, 30%…80% SOC (State of Charge) when charging at different charging rate, draw the rate-negative electrode potential curve at different SOC state, linear fitting to obtain the charging rate corresponding to the negative electrode potential of 0V at different SOC state, which is the charging window at this SOC state, respectively recorded as C10% SOC, C20% SOC, C30% SOC, C40% SOC, C50% SOC, C60% SOC, C70% SOC, C80% SOC, according to the formula (60 / C20% SOC+60 / C30% SOC+60 / C40% SOC+60 / C50% SOC+60 / C60% SOC+60 / C70% SOC+60 / C80% SOC) x 10% to calculate the charging time T(min) of the secondary battery from 10% SOC to 80% SOC. The shorter the time, the better the fast charging performance of the secondary battery.

[0227] 7. 60℃ storage performance test

[0228] At 25℃, the cell is charged at 0.33C constant current to a voltage of 3.65V, then charged at 3.65V constant voltage to a current ≤0.05C, then the battery is discharged at 0.33C constant current to a voltage of 2V, and the actual discharge capacity of the battery is recorded as C0.

[0229] At 25℃, the battery is continuously charged at 0.33C0 constant current to a voltage of 3.65V, then charged at 3.65V constant voltage to a current ≤0.05C0, at this time the battery is fully charged, the volume of the battery is measured as the volume before storage. The fully charged battery is placed in a constant temperature oven at 60℃ for storage, after 30 days of storage, the battery is taken out of the constant temperature oven and the volume is measured.

[0230] The gas production of the battery stored at 60℃ for 30 days (ml / Ah) = (the volume of the battery after 30 days of storage-the volume before storage) / the rated capacity of the battery

[0231] 7. 60℃ storage performance test

[0232] The prepared lithium ion secondary battery was first charged to 3.65V at a constant current of 0.33C at 60°C, further charged to a current of 0.05C at a constant voltage of 3.65V, then discharged to 2V at a constant current of 0.33C, and the discharge capacity C0 was the discharge capacity before high-temperature storage of the lithium ion secondary battery; then the lithium ion secondary battery was charged to 3.65V at a constant current of 0.33C, and charged to a current of 0.05C at a constant voltage of 3.65V, and the lithium ion battery was fully charged. The battery was placed in a 60°C oven for 60 days, the battery was taken out, and the battery was placed in a 25°C environment, and discharged at 0.33C, and the discharge capacity was recorded as C1; the capacity retention rate = (C1 / C0) x 100%

[0233] The battery preparation parameters and battery test results are shown in Table 1 and Table 2, respectively.

[0234] As can be seen from Example 1 and Comparative Example 1, under the same conditions, compound 1-1 (ethyl acetate) can shorten the charging time compared to DMC.

[0235] As can be seen from Example 1 and Comparative Example 2, in the electrolyte with ethyl acetate as one of the organic solvents, the addition of a cyclic organic base can significantly reduce the gas production and improve the storage performance and cycle performance of the battery.

[0236] As can be seen from Examples 1, 6, and 7, controlling the mass percentage (W1) of linear carboxylate to be no more than 80% can improve the storage performance and cycle performance of the battery while ensuring fast charging performance.

[0237] As can be seen from Examples 1, 55-60, controlling W2 within a suitable range is beneficial to reducing the gas production while ensuring fast charging performance, and improving the cycle performance and storage performance of the battery.

[0238] As can be seen from Examples 1, 61-64, controlling the BET of the negative electrode active material within a suitable range is beneficial to reducing the gas production and improving the cycle performance and storage performance of the battery.

[0239] As can be seen from Examples 1, 65-68, controlling the porosity of the negative electrode active material coating within a suitable range is beneficial to reducing the gas production while ensuring fast charging performance, and improving the cycle performance and storage performance of the battery.

[0240] It can be seen from Examples 1, 69-72 that selecting a suitable unit area coating weight of the negative electrode plate is beneficial to improving the cycle performance and storage performance of the battery while ensuring the fast charging performance.

[0241] Although the present application has been described with reference to the preferred embodiments, various modifications can be made to it without departing from the scope of the application. In particular, the technical features mentioned in each of the embodiments can be combined in any manner as long as 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 non-aqueous electrolyte, comprising an organic solvent and an additive; the organic solvent comprises a first organic solvent, the first organic solvent being a linear carboxylic acid ester; the additive comprises a first additive, the first additive being a cyclic organic base additive. 2.The non-aqueous electrolyte of claim 1, wherein the cyclic organic base is an aromatic ring organic base or a non-aromatic ring organic base (optionally a saturated or unsaturated non-aromatic ring organic base); optionally, the cyclic organic base is a monocyclic or fused bicyclic ring containing 5-12 ring atoms. Optionally, the cyclic organic base additive includes any one or more of compound 1 of general formula (I), compound 2 of general formula (II), compound 3 of general formula (IV), compound 4 of general formula (V) or (V’), and compound 5 of general formula (VI), In general formula (III), Y 1 , Y 2 are identical or different, Y 1 , Y 2 are each independently selected from CH, N; R 11 , R 12 , R 13 are each independently selected from the group consisting of H, Ci-C6-alkyl, C2-C6-alkenyl, C2-C6-alkynyl, halogen, -R 14 OH, -R 15 NR 16 R 17 , -R 18 -O-R 19 , C3-C5-cycloalkyl, wherein, R 14 , R 15 , R 18 are each independently selected from the group consisting of: nothing, C1-C6alkylene, C2-C6alkenylene, R 16 , R 17 , R 19 are each independently selected from the group consisting of hydrogen, halogen, C1-C6alkyl, C1-C6haloalkyl, and as R 16 , R 17 , R 19 any carbon atom in the C1-C6alkyl group of R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen containing heterocyclic ring; In general formula (II), W 1 and W 2 are the same or different, W 1 is selected from C, N, O, S, W 2 is selected from C, N, and W 1 at least one of W 2 and W 21 is N; R 22 , R 23 , R 24 are each independently selected from the following groups: H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, halogen, -R 25 OH, -R 26 NR 27 R 28 , -R 29 -O-R 30 , C3-C5 cycloalkyl, wherein R 25 , R 26 , R 29 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 27 , R 28 , R 30 are each independently selected from a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl; In general formula (IV), A 1 , A 2 , A 3 , A 4 , A 5 , A 6 , A 7 may be the same or different, each independently C or N, and A 1 , A 2 , A 3 , A 4 and A 5 at least one of A 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, halogen, -OH, -R 38 NR 39 R 40 , C1-C6 alkoxy, C3-C5 cycloalkyl, wherein R 38 is absent or selected from C1-C6 alkylene, C2-C6 alkenylene, R 39 , R 40 each independently is selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl; In general formula (V), X 1 , X 2 , X 3 are each independently C or N, and at least one of X 1 , X 2 , X 3 is N, in general formula (V’), X 1 , X 3 are each independently C or N, and at least one of X 1 , X 3 is N, In general formula (V) and (V’), a, b are each independently selected from 0, 1, 2, 3, c is selected from 1, 2, 3, 4, 5, 6, 7, 8, each R 41 is each independently selected from H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, halogen, -R 42 OH, -R 43 NR 44 R 45 , -R 46 -O-R 47 , C3-C5 cycloalkyl, wherein R 42 , R 43 , R 46 is each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 44 , R 45 , R 47 is each independently selected from hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl; In general formula (VI), V 1 , V 2 , V 3 are each independently C or N, and at least one of V 1 , V 2 , V 3 is N, d is selected from 0, 1, 2, 3, e is selected from 1, 2, 3, 4, 5, 6, each R 51 is independently selected from H, C1-C6 alkyl, C2-C6 alkenyl, C2-C6 alkynyl, halogen, -R 52 OH, -R 53 NR 54 R 55 , -R 56 -O-R 57 , C3-C5 cycloalkyl, wherein R 52 , R 53 , R 56 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 54 , R 55 , R 57 are each independently selected from a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl.

3. The nonaqueous electrolyte according to claim 2, wherein In general formula (II), Y 1 , Y 2 are both N, or one of Y 1 , Y 2 is N and the other is CH.

4. The nonaqueous electrolyte according to claim 2 or 3, wherein In general formula (II), the R 11 , R 12 , R 13 each independently is selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 14 OH, -R 15 NR 16 R 17 , -R 18 -O-R 19 , wherein R 14 , R 15 , R 18 each independently is selected from the group consisting of nothing, C1-C3 alkylene, R 16 , R 17 , R 19 each independently is selected from the group consisting of hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl, and any carbon atom of the C1-C3 alkyl as the R 16 , R 17 , R 19 may be substituted with one or more heteroatoms, which are N atoms, optionally, R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen-containing heterocyclic ring.

5. The nonaqueous electrolyte according to any one of claims 2 to 4, wherein said R 11 , R 12 , R 13 are each independently selected from the group consisting of hydrogen, halogen, methyl, ethyl, n-propyl, i-propyl, t-butyl, allyl, propargyl, -OH, -CH2OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3, Optionally, said R 11 , R 12 , R 13 are each independently selected from the group consisting of hydrogen, fluorine, methyl, t-butyl, -CH2OH, -CH2NH2, -N(CH3)2, -O-CH3, Any one of the group consisting of 6. The nonaqueous electrolyte according to any one of claims 2 to 5, wherein The compounds having the structure of Formula (II) are selected from any one or more of the following compounds:

7. The nonaqueous electrolyte according to claim 2, in general formula (III), W 1 and W 2 are each N, or one of W 1 , W 2 is N and the other is CH.

8. The nonaqueous electrolyte according to claim 2 or 7, wherein the R 21 , R 22 , R 23 , R 24 each independently is selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 25 OH, -R 26 NR 27 R 28 , -R 29 -O-R 30 , C3-C5 cycloalkyl, wherein, R 25 , R 26 , R 29 are each independently selected from the group consisting of: nothing, C1-C4alkylene, R 27 , R 28 , R 30 are each independently selected from the group consisting of hydrogen, halogen, C1-C4alkyl, C1-C4haloalkyl.

9. The nonaqueous electrolyte according to claim 2, 7 or 8, wherein, said R 21 , R 22 , R 23 , R 24 are each independently selected from the group consisting of hydrogen, fluorine, methyl, ethyl, propyl, cyclopropyl, allyl, propargyl, -OH, -CH3OH, -NH2, -NHCH3, -CH2NH2, -N(CH3)2, -O-CH3; optionally, said R 21 , R 22 , R 23 , R 24 are each independently selected from the group consisting of hydrogen, fluorine, methyl, cyclopropyl, allyl, -CH3OH, -NHCH3.

10. The nonaqueous electrolyte according to any one of claims 2 or 7 to 9, wherein The compounds having the structure according to general formula (III) are selected from any one or more of the following compounds:

11. The nonaqueous electrolyte according to claim 2, in the general formula (IV), A 1 is N, A 2 , A 3 , A 4 , A 5 , A 6 , A 7 each independently is C or N; Optionally, A 1 is N, and A 5 is C.

12. The nonaqueous electrolyte according to claim 2 or 11, wherein R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently is selected from any one of hydrogen, C1-C4 alkyl, C2-C4 alkenyl, C2-C4 alkynyl, -OH, -R 38 NR 39 R 40 , C1-C4 alkoxy, R 38 is absent or selected from C1-C3 alkylene, R 39 , R 40 each independently is selected from hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl; Optionally, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently is selected from the group consisting of hydrogen, methyl, ethyl, allyl, propargyl, -OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3; Optionally, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 are each independently selected from the group consisting of hydrogen, methyl, -O-CH3.

13. The non-aqueous electrolyte according to any one of claims 2 or 10-12, wherein in the general formula (IV), R 32 R 33 R 34 R 35 R 36 R 37 All are hydrogen; Optionally, R 31 is selected from hydrogen, methyl, ethyl, allyl, propargyl, -OH, -NH2, -CH2NH2, -N(CH3)2, -O-CH3; Optionally, R 31 is selected from hydrogen, methyl, -O-CH3.

14. The nonaqueous electrolyte according to any one of claims 2 or 10 to 13, wherein, The compound having the structure of Formula (IV) is selected from any one or more of the following compounds:

15. The nonaqueous electrolyte according to claim 2, wherein in the general formula (V), X 1 is N, X 2 , X 3 is each independently C or N; optionally, X 2 is N; optionally, X 3 is C. In the general formula (V), X 1 , X 3 are each N. 16.The non-aqueous electrolyte of claim 2 or 15, wherein in the general formula (V), a, b, c are each independently 1, 2 or 3; optionally, a is 2; optionally, b is 1, 2 or 3; optionally, c is 1 or 2. In the general formula (V’), a is 0 or 1, and c is 1 or 2.

17. The nonaqueous electrolyte according to claim 2, 15 or 16, wherein the general formula (V) is (V-1) : ###00011### wherein a, b, X 1 , X 2 , X 3 as defined in claim 2, 15 or 16; The general formula (V) is (V-1): wherein a, X 1 , X 3 as defined in claim 2, 15 or 16.

18. The nonaqueous electrolyte according to any one of claims 2 or 15 to 17, in the general formula (V), (V'), (V-1) or (V'-1), each R 41 each independently is selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 42 OH, -R 43 NR 44 R 45 , -R 46 -O-R 47 , R 42 , R 43 , R 46 each independently is selected from the group consisting of nothing, C1-C3 alkylene, R 44 , R 45 , R 47 each independently is selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl; Optionally, each R 41 Each is independently selected from hydrogen, fluorine, methyl, ethyl, hydroxyl, -NH2, -N(CH3)2; Optionally, each R 41 each independently is selected from hydrogen, methyl, -N(CH3)2.

19. The nonaqueous electrolyte according to any one of claims 2 or 15 to 18, wherein The compound having the structure according to Formula (V) is selected from any one or more of the following compounds: 20.The non-aqueous electrolyte of claim 2, wherein in the general formula (VI), d is 0 or 1.

21. The nonaqueous electrolyte according to claim 2 or 20, wherein each R 51 is independently selected from the group consisting of hydrogen, halogen, Ci-C4alkyl, C3-C5alkenyl, C3-C5alkynyl, -R 52 OH, -R 53 NR 54 R 55 , -R 56 -O-R 57 , wherein, R 52 , R 53 , R 56 are each independently selected from the group consisting of: nothing, C1-C3 alkylene, R 54 , R 55 , R 57 are each independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl; Optionally, each R 51 Each is independently selected from hydrogen, fluorine, methyl, ethyl, n-propyl, isopropyl, n-butyl, tert-butyl, hydroxyl, -NH2, -N(CH3)2; Optionally, each R 51 each independently is selected from hydrogen, fluorine, methyl, ethyl, isopropyl, tert-butyl.

22. The nonaqueous electrolyte according to any one of claims 2, 20 or 21, wherein, The compound having the structure according to Formula (VI) is selected from any one or more of the following compounds:

23. The nonaqueous electrolyte of any one of claims 1 to 22, wherein, The mass percentage of the first additive in the non-aqueous electrolyte is W2, and W2 satisfies 0.1%≤W2≤10%, optionally 0.1%≤W2≤5%, further optionally 0.5%≤W2≤3%.

24. The nonaqueous electrolyte of any one of claims 1 to 23, wherein, said linear carboxylic acid ester is selected from one or more of the compounds of general formula (I), wherein R1 and R2 are each independently selected from C1-C6 alkyl, C1-C6 haloalkyl; optionally, R1 and R2 are each independently selected from C1-C3 alkyl, C1-C3 haloalkyl; optionally, R1 and R2 are each independently selected from methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl; Optionally, the linear carboxylic acid ester is selected from one or more of the following compounds: Optionally, the linear carboxylic acid ester is selected from one or more of the following compounds: 25.The non-aqueous electrolyte of any one of claims 1-24, wherein the mass percentage of the first organic solvent based on the total mass of the organic solvent is W1, and W1 satisfies 20%≤W1≤80%; optionally, W1 satisfies 30%≤W1≤70%. 26.The non-aqueous electrolyte of any one of claims 1-25, wherein the organic solvent further comprises a second organic solvent; optionally, the second organic solvent comprises one or more of cyclic carbonate or chain carbonate, and optionally, the second organic solvent is selected from ethylene carbonate (EC), methyl ethyl carbonate (EMC), or a combination thereof. 27.The non-aqueous electrolyte of any one of claims 1-26, wherein the additive further comprises a second additive, and optionally, the second additive comprises one or more of a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive capable of improving battery performance.

28. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte, wherein The electrolyte is the non-aqueous electrolyte of any one of claims 1-27.

29. The secondary battery of claim 28, the negative active material having a BET specific surface area of 0.5 m2 / g ~ 2.0 m2 / g; optionally, the negative active material having a BET specific surface area of 0.8 m2 / g ~ 1.5 m2 / g. 2 / g ~ 2.0 m 2 / g. The negative active material has a BET specific surface area of 0.8 m 2 / g ~ 1.5 m 2 / g. The negative active material has a BET specific surface area of 0.8 m 30.The secondary battery of any one of claims 28 or 29, wherein in the negative electrode sheet, the porosity of the negative electrode active material coating is P, and P satisfies 20%≤P≤60%; optionally, P satisfies 25%≤P≤45%.

31. The secondary battery according to any one of claims 28-30, a coated weight per unit area of the negative electrode sheet being CW, CW satisfying 7 mg / cm 2 ≤ CW ≤ 15 mg / cm 2 ; optionally, CW satisfying 9 mg / cm 2 ≤ CW ≤ 13 mg / cm 2 .

32. An electrically powered device comprising a secondary battery, wherein, The secondary battery comprises the secondary battery of any one of claims 28-31.

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