Non-aqueous electrolyte for improving high-temperature cycling and storage, secondary battery, and electrical apparatus

Abstract

A non-aqueous electrolyte for improving high-temperature cycling and storage, a secondary battery, and an electrical apparatus. The non-aqueous electrolyte comprises an organic solvent and an additive. The organic solvent comprises a first organic solvent, the first organic solvent comprising ethylene carbonate (EC), the mass content of EC in the electrolyte being W1, and W1 satisfying 0<W1≤30%. The additive comprises a first additive, the first additive being a cyclic organic base additive. In one aspect, the oxidation resistance of the electrolyte is enhanced by means of reducing the content of EC; in another aspect, protons in the electrolyte are captured by means of the organic base additive, so that the damaging effect of the protons on a negative electrode is reduced, thereby prolonging the service life of the battery.

Description

Non-aqueous electrolyte, secondary battery and power consuming device with improved high-temperature cycling and storage

[0001] Cross-reference to Related Applications

[0002] This application is based on and claims priority to CN application No. 202410881070.6, 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 consuming 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] Researchers have obtained batteries with higher capacity density by improving the specific capacity of positive and negative electrode materials and the average voltage of positive electrode materials. However, with the increase of energy density and voltage, the electrolyte limits the improvement of battery life. Traditional carbonate solvents and LiPF6 electrolytes cannot perform better at higher voltages, mainly because the instability of commonly used solvents and salt solutions at high pressure will affect the performance of the battery, and thus deteriorate the cycle storage life.

[0006] In particular, a positive electrode with a higher voltage will promote the dehydrogenation and oxidation of the solvent ethylene carbonate (EC), and the removed proton hydrogen will further induce the decomposition of fluorine-containing lithium salt, and thus form HF. HF will attack the SEI film on the negative electrode side during the cycle storage process, causing the SEI components to dissolve into the electrolyte again, resulting in a loose and porous SEI. The instability of the SEI will cause the electrolyte to directly contact the negative electrode, thereby causing the electrolyte to decompose and increasing the consumption of active lithium, and thus deteriorating the cycle storage life of the battery. The traditional additives mainly form a film on the negative electrode side to increase the protection ability of the SEI, but on the one hand this may cause an increase in impedance; on the other hand, protons are more likely to form under high pressure, and the interaction between the protons and the negative electrode is amplified at high temperature. Therefore, the traditional method of reinforcing the SEI by adding additives is difficult to meet the higher cycle storage life requirements. SUMMARY

[0007] In view of the problems in the background art, one of the objects of the present application is to provide an electrolyte, which can improve the oxidation resistance of the electrolyte and further reduce the proton interaction by reducing the content of EC and adding a proton-capturing organic base additive.

[0008] The present application provides a non-aqueous electrolyte, a secondary battery and a power device to solve the above problems.

[0009] The first aspect of the present application provides a non-aqueous electrolyte, which comprises an organic solvent and an additive, the organic solvent comprises a first organic solvent, the first organic solvent is ethylene carbonate, wherein the mass content of ethylene carbonate in the electrolyte is W1, W1 satisfies 0 < W1 ≤ 30%; the additive comprises a first additive, the first additive is a cyclic organic base additive.

[0010] The present application enhances the oxidation resistance of the electrolyte by reducing the content of EC, and on the other hand, reduces the damage of protons to the negative electrode by capturing the protons in the electrolyte with the organic base additive, thereby prolonging the service life of the battery.

[0011] In some embodiments, the cyclic organic base is an aromatic ring organic base or a non-aromatic ring organic base (e.g. 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.

[0012] 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 (III), compound 4 represented by general formula (IV) or general formula (IV'), and compound 5 represented by general formula (V),

[0013] 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-R19 C3-C5 cycloalkyl, wherein R 14 R 15 R 18 each independently is selected from the group consisting of: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 16 R 17 R 19 each independently is selected from the group consisting of hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl, and as R 16 R 17 R 19 any carbon atom in the C1-C6 alkyl 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;

[0014] 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 at least one of W1and W2is N; R 21 R 22 R 23 R 24 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), -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 is selected from the group consisting of: nothing, C1-C6 alkylene, C 2- C6 alkenylene, R 27 R 28 R 30 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 (III), A 1 A 2 A 3 A 4 A5 , 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 at least one (e.g. 1, 2, 3 or 4) of A 5 is N; R 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 (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 is selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl;

[0016] In general formula (IV), 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 (IV’), X 1 , X 3 each independently is C or N, and at least one of X 1 , X 3 is N,

[0017] In general formula (IV) and (IV’), 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, CI, Br or I), -R 42 OH, -R 43 NR 44 R45 , -R 46 -O-R 47 , C3-C5 cycloalkyl, wherein R 42 , R 43 , R 46 are each independently selected from the group consisting of: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 44 , R 45 , R 47 are each independently selected from the group consisting of hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl;

[0018] In general formula (V), 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, and each R 51 is 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, 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 are each independently selected from the group consisting of: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 54 , R 55 , R 57 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6 alkyl, C1-C6 haloalkyl.

[0019] In some embodiments, in general formula (I), Y 1 , Y 2 are each N, or, one of Y 1 , Y 2 is N and the other is CH.

[0020] In some embodiments, in general formula (I), the R 11 , R 12 , R 13 are each independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R14 OH, -R 15 N R 16 R 17 , -R 18 -O-R 19 , wherein R 14 , R 15 , R 18 are each independently selected from the group consisting of: nothing, C1-C3 alkylene, R 16 , R 17 , R 19 are each independently selected from the group consisting of hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl, and as said R 16 , R 17 , R 19 any carbon atom in the C1-C3 alkyl group of said R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen containing heterocyclic ring.

[0021] In some embodiments, in general formula (I), 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, In some embodiments, 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 following:

[0022] In some embodiments, the compound having the structure according to general formula (I) is selected from any one or more of the following compounds:

[0023] In some embodiments, in general formula (II), W 1 and W 2 are both N, or one of W 1 , W 2 is N and the other is CH.

[0024] In some embodiments, in general formula (II), said R 21 , R 22 , R 23 , R 24each independently selected from the group consisting of hydrogen, halogen, C1-C4alkyl, C3-C5alkenyl, C3-C5alkynyl, -R 25 OH, -R 26 NR 27 R 28 , -R 29 -O-R 30 , C3-C5cycloalkyl, 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.

[0025] In some embodiments, in general formula (II), 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.

[0026] In some embodiments, the compound having the structure according to general formula (II) is selected from any one or more of the following compounds:

[0027] In some embodiments, in general formula (III), 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.

[0028] In some embodiments, in general formula (III), the R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R37 each independently 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 selected from C1-C3alkylene, R 39 , R 40 each independently selected from the group consisting of hydrogen, halogen, C1-C3alkyl, C1-C3haloalkyl. In some embodiments, R 31 , R 32 , R 33 , R 34 , R 35 , R 36 , R 37 each independently 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 selected from the group consisting of hydrogen, methyl, -O-CH3.

[0029] In some embodiments, in general formula (III), R 32 , R 33 , R 34 , R 35 , R 36 , R 37 are each 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.

[0030] In some embodiments, the compound having the structure according to general formula (III) is selected from any one or more of the following compounds:

[0031] In some embodiments, in general formula (IV), 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.

[0032] In some embodiments, in the general formula (IV), 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.

[0033] In some embodiments, in the general formula (IV’), a is 0 or 1, and c is 1 or 2.

[0034] In some embodiments, the general formula (IV) is (IV-1):

[0035] wherein a, b, X 1 , X 2 , X 3 are as defined above.

[0036] In some embodiments, the general formula (IV’) is (IV’-1):

[0037] wherein a, X 1 , X 3 are as defined above.

[0038] In some embodiments, in the general formula (IV), (IV’), (IV-1), or (IV’-1), each R 41 is each independently selected from 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 are each independently selected from: nothing, C1-C3 alkylene, R 44 , R 45 , R 47 are each independently selected from hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. In some embodiments, each R 41 are each independently selected from hydrogen, fluorine, methyl, ethyl, hydroxyl, -NH2, -N(CH3)2. In some embodiments, each R 41 are each independently selected from hydrogen, methyl, -N(CH3)2.

[0039] In some embodiments, the compound having the structure represented by the general formula (IV) is selected from any one or more of the following compounds:

[0040] In some embodiments, in general formula (V), d is 0 or 1.

[0041] In some embodiments, in general formula (V), each R 51 is independently selected from hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 52 OH, -R 53 NR 54 R 55 , -R 56 -O-R 57 , wherein R 52 , R 53 , R 56 is independently selected from: nothing, C1-C3 alkylene, R 54 , R 55 , R 57 is independently selected from hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. In some embodiments, each R 51 is independently selected from hydrogen, fluorine, methyl, ethyl, n-propyl, isopropyl, n-butyl, t-butyl, hydroxyl, -NH2, -N(CH3)2. In some embodiments, each R 51 is independently selected from hydrogen, fluorine, methyl, ethyl, isopropyl, t-butyl.

[0042] In some embodiments, the compound having the structure represented by general formula (V) is selected from any one or more of the following compounds:

[0043] In some embodiments, the mass percentage of the first additive in the non-aqueous electrolyte is W2, W2 satisfies 0.1%≤W2≤20%, optionally 0.1%≤W2≤10%, further optionally 1%≤W2≤5%. W2 within the above range is more conducive to improving the cycle performance and storage performance of the battery.

[0044] 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%.

[0045] In some embodiments, the mass content of ethylene carbonate in the electrolyte is W1, W1 satisfies 0

[0046] In some embodiments, W1 is 10%~15%, 15%~20%, 20%~25% or 25%~30%.

[0047] In some embodiments, the non-aqueous electrolyte of the present application further comprises a second organic solvent, which optionally comprises one or more of a chain carbonate other than cyclic carbonate or ethylene carbonate. The second organic solvent can be selected to provide the battery with better fast charging performance.

[0048] In some embodiments, the non-aqueous electrolyte of the present application further comprises a second additive, which optionally 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.

[0049] 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.

[0050] In some embodiments, the specific surface area of the positive electrode sheet is A, wherein 0 < A ≤ 20 cm 2 / g. In some embodiments, 2 cm 2 / g ≤ A ≤ 10 cm 2 / g. By controlling the specific surface area of the positive electrode sheet, the contact area between the positive electrode sheet and the electrolyte can be reduced, the probability of EC oxidative dehydrogenation can be reduced, and the generation of protons can be reduced, while the polarization of the lithium ion battery is not too large, and the capacity of the lithium ion battery is not affected.

[0051] In some embodiments, the resistance R of the positive electrode sheet is greater than 0 and not higher than 1 Ω. In some embodiments, 0 < R ≤ 0.8 Ω. In some embodiments, 0 < R ≤ 0.5 Ω. By controlling the resistance of the positive electrode sheet containing the inorganic dielectric layer to be not higher than 1 Ω, the stability and safety performance of the battery system can be improved, and the battery has good kinetic performance and rate performance, thereby prolonging the cycle life of the battery.

[0052] The third aspect of the present application provides a power-using device comprising a secondary battery, wherein the secondary battery comprises the secondary battery provided by any of the embodiments of the second aspect. BRIEF DESCRIPTION OF DRAWINGS

[0053] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed 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.

[0054] FIG. 1 is a schematic diagram of a secondary battery according to an embodiment of the present application.

[0055] FIG. 2 is an exploded view of the secondary battery of the embodiment of the present application shown in FIG. 1.

[0056] FIG. 3 is a schematic view of the battery module of the embodiment of the present application.

[0057] FIG. 4 is a schematic view of the battery pack of the embodiment of the present application.

[0058] FIG. 5 is an exploded view of the battery pack of the embodiment of the present application shown in FIG. 4.

[0059] FIG. 6 is a schematic view of the power-using device using the secondary battery of the embodiment of the present application as a power source.

[0060] In the drawings, the drawings are not drawn to scale.

[0061] 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

[0062] The 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 drawings are intended to exemplify the principles of the present application, but cannot be used to limit the scope of the present application, i.e., the present application is not limited to the described examples.

[0063] Hereinafter, the embodiments of the non-aqueous electrolyte solution, the secondary battery, and the power-using device of the present application are specifically disclosed in detail with appropriate reference to the accompanying drawings. However, there will be cases where unnecessary detailed description is omitted. For example, there will be cases where detailed description of matters that are already well known, repeated description of actually 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.

[0064] The ranges disclosed herein are meant to be inclusive of the endpoints and include the end values in the range. Ranges can be combined to form new ranges, e.g., a range of "60-120 and 80-110" is understood to include 60-110 and 80-120. Further, if a minimum range value is listed as 1 and a maximum range value is listed as 3, 4, and 5, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise indicated, a numerical range "a-b" means a range of any combination of the numbers a and b, wherein both a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between 0 and 5 have been listed herein, and "0-5" is merely a shorthand for listing all of those numbers. Also, when a parameter is stated to be an integer > 2, it is equivalent to state that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0065] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0066] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0067] All steps of the present application can be performed in sequence or randomly, preferably in sequence, unless otherwise specified. 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 further 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.

[0068] If not specifically stated, "including" and "containing" mentioned in the present application means open. For example, "including" and "containing" can mean that other components not listed can also be included or contained.

[0069] The term "or" is inclusive in this application, unless otherwise indicated. So for example, either or both of A or B can be true (or present) A is true (or present) and B is false (or not present); A is false (or not present) and B true (or present); or both A and B are true (or present).

[0070] The term "cyclic organic base" refers to a basic compound having a cyclic structure composed of one or more nitrogen atoms and carbon atoms.

[0071] The term "alkyl" denotes a straight-chain or branched-chain hydrocarbon group, for example "C 1-20 alkyl", "C 1-10 alkyl", "C 1-6 alkyl", "C 1-4 alkyl", "C 1-3 alkyl" and the like, specific examples of which include, but are not limited to: methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t-butyl, n-pentyl, i-pentyl, 2-methylbutyl, neopentyl, 1-ethylpropyl, n-hexyl, i-hexyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 2-ethylbutyl, 1,2-dimethylpropyl and the like.

[0072] The term "alkylene" refers to a divalent straight-chain or branched-chain alkyl radical, consisting solely of carbon and hydrogen atoms, containing no degree of unsaturation, and being attached to the rest of the molecule by single bonds, including, but not limited to methylene, etc. For example, "C 1-6 alkylene" refers to a saturated divalent straight-chain or branched-chain hydrocarbon radical containing from 1 to 6 carbon atoms.

[0073] The term "alkenyl" refers to a straight-chain or branched-chain hydrocarbon group containing at least one carbon-carbon double bond, including, for example, "C 2-6 alkenyl", "C 2-4 alkenyl" and the like. Examples include, but are not limited to: ethenyl, 1- propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 1,3-buten-yl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 1,3-pentadienyl, 1,4-pentadienyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 1,4-hexadienyl and the like.

[0074] The term "alkenylene" refers to a divalent straight-chain or branched-chain alkyl radical, consisting solely of carbon and hydrogen atoms, containing at least one double bond, and being attached to the rest of the molecule by single bonds, including, but not limited to etc. For example, "C2-6alkenylene" refers to a divalent straight or branched chain hydrocarbon group containing 2 to 6 carbon atoms and having at least one carbon-carbon double bond (>C=C<).

[0075] The term "alkynyl" refers to straight or branched chain hydrocarbon groups containing at least one carbon-carbon triple bond. Included within this term are, for example, "C2-6alkynyl", "C2-6alkynyl", "C2-6alkynyl", etc. 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, etc. 2- 6alkynyl", "C 4-6 alkynyl", etc. 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, etc.

[0076] 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. If valence requirements are met, a heterocyclyl group can be attached to the remainder of the molecule through any one of the ring atoms. The term "5-6 membered nitrogen-containing heterocycle" as used herein 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 groups in the present application can optionally be fused with one or more aromatic or non-aromatic rings.

[0077] The term "cycloalkyl" refers to a monocyclic or polycyclic group comprising a saturated or partially unsaturated (e.g., containing 1 or 2 double bonds) ring. "Monocycloalkyl" is preferably a 3-10 membered monocycloalkyl, more preferably a 3-8 membered monocycloalkyl, for example: cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclodecyl, cyclododecyl, cyclohexenyl. "Polycycloalkyl" includes "bridged cycloalkyl", "fused cycloalkyl", and "spiro cycloalkyl", "bridged cycloalkyl" refers to a monocycloalkyl group in which any two non-adjacent carbon atoms are connected by an alkylene bridge of 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.

[0078] 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.

[0079] 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.

[0080] The term "halogenated" or "halogenated" is defined as including F, Cl, Br, or I.

[0081] 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.

[0082] As used herein, the term "one or more" means one or more under reasonable conditions, such as two, three, four, five, or ten.

[0083] The term "independently" means that at least two groups (or ring systems) present 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.

[0084] Unless specified, the point of attachment of a substituent as used herein can come from any suitable position of the substituent.

[0085] 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.

[0086] [Non-aqueous electrolyte]

[0087] 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 vinyl carbonate, wherein the mass content of vinyl carbonate in the electrolyte is W1, W1 satisfies 0 < W1 ≤ 30%; the additive comprising a first additive, the first additive being a cyclic organic base type additive.

[0088] The present application reduces the content of EC, reduces the probability of contact between EC and the positive electrode, and slows down the occurrence of dehydrogenation oxidation. However, the dehydrogenation oxidation of EC will still become more severe as the temperature rises, so the present application introduces a proton-capturing organic base type additive into the electrolyte. The present application uses the first additive in combination with the first organic solvent, on the one hand, to enhance the oxidation resistance of the electrolyte by reducing the content of EC, and on the other hand, to capture protons in the electrolyte by the organic base type additive, to reduce the destructive effect of protons on the negative electrode, thereby achieving the extension of the battery life.

[0089] 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 (I), (II) or (III). Exemplary saturated non-aromatic ring organic bases can be seen in compounds represented by general formula (V). Exemplary unsaturated non-aromatic ring organic bases can be seen in compounds represented by general formula (IV) or (IV’).

[0090] 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.

[0091] The present application employs a cyclic organic base as an electrolyte additive. Compared with acyclic organic bases, the alkyl group of the heteroatom on the cyclic organic base has a smaller bond angle due to the effect of the ring, fully exposing the lone pair of electrons on the heteroatom, so the heteroatom generally has stronger nucleophilic ability and stronger ability to capture free protons in the electrolyte, reducing the damage of SEI to the negative electrode.

[0092] 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 (III), compound 4 represented by general formula (IV) or general formula (IV’), and compound 5 represented by general formula (V).

[0093] In general formula (I), Y 1 , Y 2 , 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 19 Any carbon atom in the C1-C6alkyl 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.

[0094] 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 at least one of W1and W2is N; R 21 , R 22 , R 23 , R 24 are each independently selected from the group consisting of H, C1-C6alkyl, C2-C6alkenyl (e.g., allyl (H2C=CH-CH2-)), C2-C6alkynyl (e.g., propargyl (-CH2C≡CH)), halogen (e.g., F, Cl, Br, or I), -R 25 OH, -R 26 NR 27 R 28 , -R 29 -O-R 30 , C3-C5cycloalkyl, wherein R 25 , R 26 , R 29 are each independently selected from the group consisting of nothing, C1-C6alkylene, C2-C6alkenylene, R 27 , R 28 , R 30 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, C1-C6alkyl, C1-C6haloalkyl.

[0095] In general formula (III), 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, R 34 , 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 hydrogen atom, halogen atom, C1-C6 alkyl, C1-C6 haloalkyl.

[0096] In general formula (IV), 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 (IV’), X 1 , X 3 each independently is C or N, and at least one of X 1 , X 3 is N,

[0097] In general formula (IV) and (IV’), 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 47 each independently is selected from hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl.

[0098] In general formula (V), V 1 , V 2 , V 3 are each independently C or N, and 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 are 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 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.

[0099] In some embodiments, in general formula (I), Y 1 , Y 2 are each N, or, one of Y 1 , Y 2 is N and the other is CH.

[0100] In some embodiments, in general formula (I), the R 11 , R 12 , R 13 are 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 are each independently selected from: nothing, C1-C3 alkylene, R 16 , R 17 , R 19each independently selected from the group consisting of hydrogen, halogen, C1-C3 alkyl, C1-C3 haloalkyl, and any carbon atom in said C1-C3 alkyl, C1-C3 haloalkyl is optionally substituted with one or more heteroatoms, said heteroatoms being N atoms, and R 16 , R 17 , R 19 , R 16 , R 17 and the nitrogen atom to which both are attached together form a 5-6 membered nitrogen containing heterocyclic ring.

[0101] In some embodiments, in general formula (I), R 11 , R 12 , R 13 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, R 11 , R 12 , R 13 each independently selected from the group consisting of hydrogen, fluorine, methyl, t-butyl, -CH2OH, -CH2NH2, -N(CH3)2, -O-CH3, , and any one of the group consisting of:

[0102] In some embodiments, the compound having the structure according to general formula (I) is selected from any one or more of the following compounds:

[0103] In some embodiments, in general formula (II), W 1 and W 2 are both N, or one of W 1 , W 2 is N and the other is CH.

[0104] In some embodiments, in general formula (II), R 21 , R 22 , R 23 , R 24 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 each independently selected from the group consisting of: nothing, C1-C4 alkylene, R27 28 30 each independently is selected from hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl.

[0105] In some embodiments, in general formula (II), the R 21 22 23 24 each independently is selected from hydrogen, fluorine, methyl, ethyl, propyl, cyclopropyl, allyl, propargyl, -OH, -CH3OH, -NH2, -NHCH3, -CH2NH2, -N(CH3)2, -O-CH3. In some embodiments, the R 21 22 23 24 each independently is selected from hydrogen, fluorine, methyl, cyclopropyl, allyl, -CH3OH, -NHCH3.

[0106] In some embodiments, the compound having a structure according to general formula (II) is selected from any one or more of the following compounds:

[0107] In some embodiments, in general formula (III), A 1 is N, A 2 3 4 5 6 7 each independently is C or N. In some embodiments, A 1 is N, and A 5 is C.

[0108] In some embodiments, in general formula (III), R 31 32 33 34 35 36 37 each independently is selected from 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 40 each independently is 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 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.

[0109] In some embodiments, in general formula (III), 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.

[0110] In some embodiments, the compound having the structure represented by general formula (III) is selected from any one or more of the following compounds:

[0111] In some embodiments, in general formula (IV), 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.

[0112] In some embodiments, in general formula (IV), 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.

[0113] In some embodiments, in general formula (IV’), a is 0 or 1, and c is 1 or 2.

[0114] In some embodiments, the general formula (IV) is (IV-1):

[0115] wherein a, b, X 1 , X 2 , X 3 are as defined above.

[0116] In some embodiments, the general formula (IV’) is (IV’-1):

[0117] wherein a, X 1 , X 3 are as defined above.

[0118] In some embodiments, in general formula (IV), (IV’), (IV-1), or (IV’-1), each R 41 is independently selected from hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 3- OH, -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-C3 alkylene, R 44 , R 45 , R 47 is independently selected from hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. 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.

[0119] In some embodiments, the compound having the structure of general formula (IV) is selected from any one or more of the following compounds:

[0120] In some embodiments, in general formula (V), d is 0 or 1.

[0121] In some embodiments, in general formula (V), each R 51 is independently selected from hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -R 52 OH, -R53 NR 54 R 55 , -R 56 -O-R 57 , -R 52 , R 53 , R 56 each independently is selected from the group consisting of nothing, C1-C3 alkylene, R 54 , R 55 , R 57 each independently is selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C1-C4 haloalkyl. In some embodiments, each R 51 each independently is 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 is selected from the group consisting of hydrogen, fluorine, methyl, ethyl, i-propyl, t-butyl.

[0122] In some embodiments, the compound having the structure of general formula (V) is selected from any one or more of the following compounds:

[0123] In some embodiments, the mass content of the first additive in the non-aqueous electrolyte is W2, W2 satisfies 0.1%≤W2≤20%. In some embodiments, W2 is 0-0.05%, 0.05%-0.1%, 0.1%-0.2%, 0.2%-0.5%, 0.5%-1%, 1%-5%, 5%-10%, 10%-12%, or 12%-20%. In some embodiments, W2 satisfies 0.1%≤W2≤10%. In some embodiments, W2 satisfies 1%≤W2≤5%. The content of the first additive within these ranges is more conducive to improving the cycle performance and storage performance of the battery.

[0124] In some embodiments, the mass content of ethylene carbonate in the electrolyte is W1, W1 is 0-15%, 15%-20%, 20%-25%, or 25%-30%. In some embodiments, W1 satisfies 0

[0125] In some embodiments, the organic solvent in the non-aqueous electrolyte of the present application can further comprise 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 comprise one or more of cyclic carbonates or other types of chain carbonates other than EC. The types of chain carbonates and cyclic carbonates are not particularly limited and can be selected according to actual needs.

[0126] 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 content of the second organic solvent in the electrolyte is W3, W3 satisfies 70% < W3≤ 100%; in some embodiments, W3 satisfies 80% < W3≤ 100%; in some embodiments, W3 satisfies 90% < W3≤ 100%.

[0127] In some embodiments, the non-aqueous electrolyte of the present application can further optionally include a second additive. As an example, the second additive can include a negative electrode film-forming additive, a positive electrode film-forming additive, and can also include an additive capable of improving certain performance 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, etc. 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, and a carboxylate compound.

[0128] In some embodiments, the non-aqueous electrolyte employed in the present application further includes an electrolyte, and any electrolyte that can be generally used in a non-aqueous electrolyte can be considered for application to the non-aqueous electrolyte of the present application. Those skilled in the art can select according to the battery system to which the non-aqueous electrolyte is applied, such as selecting a conventional electrolyte suitable for a secondary battery. In some embodiments, the electrolyte includes an alkali metal salt electrolyte; optionally, the electrolyte includes a lithium salt; optionally, the lithium salt includes one or more selected from the group consisting of lithium hexafluorophosphate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, and lithium bis-trifluoromethanesulfonylimide. Each of the above lithium salts can be used alone or in a mixture of 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 m and n are each independently a natural number of 9 or less.

[0129] The content of the electrolyte in the non-aqueous electrolyte can refer to the content of the electrolyte in a conventional non-aqueous electrolyte. In some embodiments, the content of the electrolyte in the non-aqueous electrolyte is 0.5 M to 2.5 M, or 0.8 M to 2 M.

[0130] [Secondary battery]

[0131] A secondary battery, also known as a rechargeable battery or a storage battery, refers to a battery that can continue to be used by activating active materials through charging after the battery is discharged.

[0132] Generally, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the charging and discharging process of the battery, active ions (e.g., lithium ions) are inserted and extracted between the positive electrode sheet and the negative electrode sheet. The separator is arranged between the positive electrode sheet and the negative electrode sheet, mainly to prevent short circuiting of the positive and negative electrodes, and can also allow the active ions to pass through. The electrolyte is between the positive electrode sheet and the negative electrode sheet, mainly to conduct the active ions.

[0133] The second embodiment of the present application provides a secondary battery including a positive electrode sheet, a negative electrode sheet, and an electrolyte, which is any one of the non-aqueous electrolytes provided in the first embodiment.

[0134] The present application reduces the content of EC in the electrolyte, and at the same time, matches with the organic alkali additive to capture protons, improves the oxidation resistance of the electrolyte, further reduces the proton interaction, and realizes the long service life of the battery cell.

[0135] [Positive electrode sheet]

[0136] The positive electrode sheet generally includes a positive electrode current collector and a positive electrode film layer arranged on at least one surface of the positive electrode current collector, and the positive electrode film layer includes a positive electrode active material.

[0137] The active specific surface area of the positive electrode sheet can represent the number of active sites participating in the reaction during the charging and discharging process of the positive electrode sheet.

[0138] In some embodiments, the active specific surface area of the positive electrode sheet can be 1 cm 2 / g to 5 cm 2 / g, 5 cm 2 / g to 8 cm 2 / g, 8 cm 2 / g to 10 cm 2 / g, 10 cm 2 / g to 15 cm 2 / g, 15 cm 2 / g to 20 cm 2 / g, or 20 cm 2 / g to 22 cm 2 / g.

[0139] In some embodiments, the active specific surface area of the positive electrode tab is A, wherein 0 < A ≤ 20 cm 2 / g. In some embodiments, 2 cm 2 / g ≤ A ≤ 10 cm 2 / g. By controlling the active specific surface area of the positive electrode tab, on the one hand, the contact area of the positive electrode tab with the electrolyte can be reduced, the probability of EC oxidative dehydrogenation can be reduced, the generation of protons can be reduced, and thus the capacity of the battery and the cyclic storage capacity can be improved, and on the other hand, the polarization of the lithium ion battery will not be too large, and the capacity of the lithium ion battery will not be affected.

[0140] The active specific surface area of the positive electrode tab is the real active area on the tab obtained by introducing a suitable electrochemical redox couple as a probe molecule into the electrolyte and measuring the electrochemical behavior. The active specific surface area of the positive electrode tab can be obtained by the following test method, which comprises the following steps:

[0141] The positive electrode tab to be tested, the negative electrode tab, and the electrolyte are assembled into a button-type half-cell, wherein the electrolyte contains an electrochemical redox probe molecule with a concentration of c, the redox potential of the probe molecule is 2 V to 4 V, and the probe molecule is dissolved in the electrolyte; a series of linear sweep voltammetry curves of different button-type half-cells at different scan rates V are tested using a Chenhua electrochemical workstation (model CHI660E), and the oxidation peak current i p (oxidation) and the reduction peak current i p (reduction) are obtained, then the peak currents i p of the series of button-type half-cells obtained are plotted against the square root of the scan rate V, and the slope K is obtained; according to the Randles Sevick equation i p = 2.69 x 10 5 x n 2 / 3 x c x D 1 / 2 x A x V 1 / 2 , wherein i p is the peak current, n is the number of electron transfer, D is the diffusion coefficient, D(oxidation) = 1.41 x 10 6 cm 2 / s, D(reduction) = 1.26 x 10 6 cm 2 / s, V is the scan rate, and A is the active surface area of the positive electrode tab, c is the concentration of the probe molecule, and the active surface area A of the positive electrode tab is calculated. The active specific surface area of the positive electrode tab is obtained by dividing the active surface area A of the positive electrode tab by the weight m of the positive electrode tab.

[0142] When a certain potential is applied, electrons are transferred to active sites on the surface of the active material in the positive electrode tab through the current collector, and then the probe molecule undergoes a redox reaction.

[0143] In the above test method, the negative electrode is a metal lithium sheet with a thickness of 0.4 mm. The electrolyte is a common electrolyte, in which ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then a fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a proportion of 1 mol / L.

[0144] In the above test method, the redox potential of the probe molecule is 2V-4V. The concentration of the probe molecule is 0.03mol / L-0.08mol / L; further preferably 0.05mol / L.

[0145] In the above test method, the probe molecule is one of hexaammine ruthenium, ferric chloride, and ferrocene; further preferably ferrocene. Because the probe molecule is preferably ferrocene, this is because the redox potential of ferrocene is very suitable for working in the potential window of the electrolyte containing lithium ions, and the test result is more accurate. This method obtains the peak current of the oxidation peak and the reduction peak by testing the cyclic voltammogram of the ferrocene solution at different scan rates on the surface of the active material, obtains the slope by fitting the current i and the scan rate V, and thus calculates the reaction active specific surface area of the tab. This method takes iron ions as the index element, and the oxidation / reduction sites of iron ions on the surface of the tab as the active sites of the tab. According to the Randles Sevick equation and the cyclic voltammogram, a linear relationship is established to obtain the active reaction area.

[0146] In the above test method, the scan rate is 0.01mV / s-3.50mV / s, the scan voltage range is 2.9V-3.5V, D(oxidation)=1.41x10 6 cm 2 / s, D(reduction)=1.26x10 6 cm 2 / s.

[0147] In some embodiments, the resistance R of the positive electrode tab is less than 0.25Ω, 0.25Ω-0.5Ω, 0.5Ω-0.6Ω, 0.6Ω-0.8Ω, 0.8Ω-0.9Ω, 0.9Ω-1.0Ω, or 1.0Ω-1.4Ω.

[0148] In some embodiments, the positive electrode tab has an electrical resistance R greater than 0 and not higher than 1 Ω. In some embodiments, 0 < R < 0.8 Ω. In some embodiments, 0 < R < 0.5 Ω. By controlling the electrical resistance of the positive electrode tab containing the inorganic dielectric layer to be not higher than 1 Ω, the battery can have good kinetic performance and rate performance while improving the stability and safety performance of the battery system, thereby prolonging the cycle life of the battery.

[0149] In the present application, the electrical resistance of the tab is in the meaning known in the art and can be measured by using instruments and methods known in the art, such as a resistance meter. In an exemplary method, the tab is cut into a circular piece of a certain area as a test sample, a resistance meter is used, and a four-wire method is used to connect the probes so that the probes are in good contact with the surface of the sample. The sample is placed in the test area, the tester is started to measure and record the data, and the average value is calculated.

[0150] As an example, the positive current collector has two opposite surfaces in the thickness direction of the positive current collector, and the positive electrode film layer is disposed on any one or both of the two opposite surfaces of the positive current collector.

[0151] In some embodiments, the positive current collector can be a metal foil or a composite current collector. For example, as a metal foil, an aluminum 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 (aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and 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.).

[0152] In some embodiments, the positive active material can use the positive active material known in the art for batteries. As an example, when the secondary battery is a lithium ion secondary battery, the positive active material can be selected from materials capable of deintercalating and intercalating lithium ions. The positive active material can include at least one of lithium-containing phosphate of olivine structure, 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 active material for a battery can also be used. These positive 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 (such as LiCoO2), lithium nickel oxide (such as LiNiO2), lithium manganese oxide (such as LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (such as LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be referred to as NCM333 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 NCM 622 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 lithium-containing olivine-structured phosphates 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, 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 0.3 Mn 0.2 O 2、 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.

[0153] 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 cycle, the molar content of Li will change.

[0154] 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 float.

[0155] When the secondary battery is a sodium-ion secondary battery, as an example, the positive active material of the sodium-ion secondary battery can include at least one of the following materials: at least one of a sodium transition metal oxide, a polyanion compound, and a Prussian blue compound. However, the present application is not limited to these materials, and other conventionally known materials that can be used as a positive active material of a sodium-ion battery can also be used.

[0156] 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 x MO2, wherein M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu, and 0 < x ≤ 1.

[0157] As an optional technical solution of the present application, the polyanion compound can be a compound having a sodium ion, a transition metal ion, and a tetrahedral (YO4) n- anion unit. The transition metal 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- .

[0158] The polyanion compound can also be a compound having a sodium ion, a transition metal ion, a tetrahedral (YO4) n- anion unit, and a halogen anion. The transition metal 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- ; and the halogen can be at least one of F, Cl, and Br.

[0159] The polyanion compound can also be a compound having a sodium ion, a tetrahedral (YO4) n- anion unit, a polyhedral (ZO y ) m+ m unit, and an optional halogen anion. 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+ ; and the halogen can be at least one of F, Cl, and Br.

[0160] Polyanionic compounds are, for example, NaFePO4, Na3V2(PO4)3 (sodium vanadium phosphate, abbreviated as NVP), 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) at least one.

[0161] Prussian blue compounds can be a type of 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 is, for example, Na 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.

[0162] In some embodiments, the positive electrode film layer further optionally includes a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylic ester resin.

[0163] 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.

[0164] In some embodiments, the positive electrode tab can be prepared by dispersing the above-mentioned components for preparing the positive electrode tab, such as the positive electrode active material, the conductive agent, the binder, and any other components, in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; coating the positive electrode slurry on a positive electrode current collector, and then drying, cold-pressing, and the like to obtain the positive electrode tab.

[0165] [Negative electrode tab]

[0166] The negative electrode tab 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.

[0167] As an example, the negative electrode current collector has two surfaces opposite in the thickness direction thereof, and the negative electrode film layer is disposed on either one or both of the two opposite surfaces of the negative electrode current collector.

[0168] In some embodiments, the negative current collector can employ a metal foil or a composite current collector. For example, as a metal foil, a copper foil can be employed. The composite current collector can include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, silver alloy, etc.) on a polymer material base layer (e.g., a base layer of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0169] 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.

[0170] In some embodiments, the negative active material coating layer can further optionally include a binder. As an example, the binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0171] In some embodiments, the negative active material coating layer can further optionally include a conductive agent. As an example, the conductive agent can be selected from at least one of super conductive carbon, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0172] In some embodiments, the negative active material coating layer can further optionally include other auxiliary agents, such as a thickening agent (e.g., sodium carboxymethyl cellulose (CMC-Na)) and the like.

[0173] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-described components for preparing the negative electrode sheet, such as the negative active material, the conductive agent, the binder, and any other components, in a solvent (e.g., deionized water) to form a negative electrode slurry, coating the negative electrode slurry on a negative current collector, and then performing processes such as drying, cold pressing, etc.

[0174] [Separator]

[0175] In some embodiments, the secondary battery further comprises a separator. The type of the separator is not particularly limited in the present application, and any known porous separator having good chemical stability and mechanical stability can be used.

[0176] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers can be the same or different, and are not particularly limited.

[0177] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be used to form an electrode assembly by a winding process or a stacking process.

[0178] In some embodiments, the secondary battery comprises a secondary battery cell, or comprises a battery module and a battery pack.

[0179] In some embodiments, the secondary battery can comprise an outer package. The outer package can be used to package the electrode assembly and the electrolyte described above.

[0180] In some embodiments, the outer package of the secondary battery can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the secondary battery can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, and polybutylene succinate, etc. can be listed.

[0181] 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 secondary battery cell 5 in a square structure as an example.

[0182] In some embodiments, referring to FIG. 2, the outer package can comprise a shell 51 and a top cover assembly 53. The shell 51 can comprise a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening communicating with the receiving cavity, and the top cover assembly 53 can be arranged on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can be used to form an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte is impregnated in the electrode assembly 52. The number of the electrode assembly 52 contained in the secondary battery cell 5 can be one or more, and a person skilled in the art can select according to the specific actual needs.

[0183] In some embodiments, the secondary battery cell can be assembled into a battery module, and the number of the secondary battery cells contained in the battery module can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery module.

[0184] 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 series along a length direction of the battery module 4. Of course, the plurality of secondary battery cells 5 can be arranged in any other manner. Further, the plurality of secondary battery cells 5 can be fixed by a fastener.

[0185] Optionally, the battery module 4 can further include a housing having an accommodation space in which the plurality of secondary battery cells 5 are accommodated.

[0186] In some embodiments, the above-described battery module can be assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and the specific number can be selected by a person skilled in the art according to the application and capacity of the battery pack.

[0187] 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 arranged on the lower box body 3 to form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0188] In addition, the application also provides a power utilization device including 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.

[0189] As the power utilization device, the secondary battery cell, the battery module, or the battery pack can be selected according to the use requirement thereof.

[0190] 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 the power utilization device for high power and high energy density of the secondary battery, the battery pack or the battery module can be used.

[0191] [Embodiment]

[0192] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to be only for the purpose of explanation of the present application, and are not to be understood as limiting the present application. In the examples, the specific techniques or conditions not mentioned are performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be obtained commercially.

[0193] The lithium ion batteries of the comparative examples and the examples were prepared according to the following method

[0194] (1) Preparation of the positive electrode sheet

[0195] The positive electrode active material LiNi0.5Mn1.5O4, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black were dissolved in the solvent N-methyl pyrrolidone (NMP) in a mass ratio of 98:1:1, and after being fully stirred and mixed uniformly, a positive electrode slurry was obtained. Then, the positive electrode slurry was uniformly coated on the positive electrode current collector, and after drying, cold pressing, and slitting, a positive electrode sheet was obtained. 0.5 Co 0.3 Mn 0.2 O2, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black were dissolved in the solvent N-methyl pyrrolidone (NMP) in a mass ratio of 98:1:1, and after being fully stirred and mixed uniformly, a positive electrode slurry was obtained. Then, the positive electrode slurry was uniformly coated on the positive electrode current collector, and after drying, cold pressing, and slitting, a positive electrode sheet was obtained.

[0196] (2) Preparation of the negative electrode sheet

[0197] The active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickening agent sodium carboxymethyl cellulose (CMC) were dissolved in the solvent deionized water in a mass ratio of 95:2:2:1, and after being uniformly mixed with the solvent deionized water, a negative electrode slurry was prepared. Then, the negative electrode slurry was uniformly coated on the negative electrode current collector copper foil, and after drying, a negative electrode film was obtained, and then cold pressing and slitting were performed to obtain a negative electrode sheet.

[0198] (3) Preparation of the electrolyte

[0199] In an argon atmosphere glove box (H2O <0.1 ppm, O2 <0.1 ppm), 1 mol / L LiPF6 was dissolved in an organic solvent, and the solvent ratio was as shown in Table 1, and after being stirred uniformly, a corresponding electrolyte was obtained.

[0200] (4) Preparation of the separator: a conventional polypropylene film was used as the separator.

[0201] (5) Preparation of the lithium ion battery

[0202] The positive electrode sheet, the separator, and the negative electrode sheet were stacked in order, with the separator 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, and after drying, the electrolyte was injected, and then the lithium ion battery was prepared through processes such as formation and standing.

[0203] Next, the test method of the physical parameters and performance parameters mentioned in the embodiments of the present application is briefly introduced.

[0204] 1. Test method of active specific surface area

[0205] The active specific surface area of the positive electrode tab is the real active area on the tab obtained by measuring the electrochemical behavior when a suitable electrochemical redox couple is introduced into the electrolyte as a probe molecule. The active specific surface area of the positive electrode tab can be obtained by the following test method, which comprises the following steps:

[0206] The positive electrode tab to be tested, the negative electrode tab, and the electrolyte are assembled into a button-type half cell, wherein the electrolyte contains an electrochemical redox probe molecule with a concentration of c, the redox potential of the probe molecule is 2V-4V, and the probe molecule is dissolved in the electrolyte; a series of linear sweep voltammograms of different button-type half cells at different scan rates V are tested using a Chenhua electrochemical workstation (model CHI660E) to obtain the oxidation peak current i p (oxidation) and the reduction peak current i p (reduction), and then the peak current i p of the obtained series of button-type half cells is plotted against the square root of the scan rate V to obtain the slope K; according to the Randles Sevick equation i p = 2.69 x 10 5 x n 2 / 3 x c x D 1 / 2 x A x V 1 / 2 , wherein i p is the peak current, n is the number of electron transfer, D is the diffusion coefficient, D(oxidation) = 1.41 x 10 6 cm 2 / s, D(reduction) = 1.26 x 10 6 cm 2 / s, V is the scan rate, A is the active surface area of the positive electrode tab, and c is the concentration of the probe molecule. After calculation, the active surface area A of the positive electrode tab is obtained. Then the active specific surface area of the positive electrode tab is obtained by dividing the active surface area A of the positive electrode tab by the weight m of the positive electrode tab.

[0207] When a certain potential is applied, electrons are transferred to the active sites on the surface of the active material in the positive electrode tab through the current collector, and the probe molecule undergoes redox reaction.

[0208] In the above test method, the negative electrode is a metal lithium sheet with a thickness of 0.4mm. The electrolyte is a common electrolyte, in which ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1, and then the fully dried lithium salt LiPF6 is dissolved in the mixed organic solvent at a proportion of 1mol / L.

[0209] In the above test method, the redox potential of the probe molecule is 2V-4V. The concentration of the probe molecule is 0.03mol / L-0.08mol / L; further preferably 0.05mol / L.

[0210] In the above test method, the probe molecule is one of hexaammine ruthenium, ferric chloride, ferrocene, and is further preferably ferrocene. Because the probe molecule is preferably ferrocene, this is because the redox potential of ferrocene is very suitable for working in the potential window of the electrolyte containing lithium ions, and the test result is more accurate. The method obtains the peak current of the oxidation peak and the reduction peak by testing the cyclic voltammogram of the ferrocene solution at different scan rates on the surface of the active material, and obtains the slope by fitting the current i and the scan rate V, so as to calculate the reaction active specific surface area of the electrode sheet. In this method, iron ions are used as the index element, and the oxidation / reduction sites of iron ions on the surface of the electrode sheet are used as the active sites of the electrode sheet. According to the Randles Sevick equation and the cyclic voltammogram, a linear relationship is established, and the active reaction area is obtained.

[0211] In the above test method, the scan rate is 0.01mV / s-3.50mV / s, the scan voltage range is 2.9V-3.5V, D(oxidation)=1.41x10 6 cm 2 / s, D(reduction)=1.26x10 6 cm 2 / s.

[0212] 2. Electrode sheet resistance test

[0213] In this application, the resistance test of the electrode sheet is the meaning known in the art, which can be measured by the instruments and methods known in the art. In this embodiment, the positive electrode sheet is cut into 1540.25mm 2 size round sheet as a test sample by using a punching machine, and a Xiamen Yuaneng Technology resistance meter (BER1100) is used to connect the probe by four-wire method to ensure good contact between the probe and the sample surface; the sample is placed in the test area, and the tester is started to measure and record 5 data, and the average value is obtained.

[0214] At 25°C, the lithium ion battery is charged at 0.33C constant current to 4.4V, then charged at 4.4V constant voltage until the current is less than or equal to 0.05C, then discharged at 0.33C constant current to 2.5V, and the actual capacity is recorded as C0(mAh). The gram capacity of the lithium ion battery is C0 / W3(mAh / g), wherein W3 is the mass of the positive active material (g).

[0215] 4. 45°C cycle performance test

[0216] The lithium ion battery was charged at 45℃ with 1C constant current to 4.4V, then charged at 4.4V constant voltage to current≤0.05C, after standing for 5min, the lithium ion battery was discharged at 1C constant current to voltage 2.5V, which was a charge and discharge cycle process, and the discharge capacity of this time was the discharge capacity of the first cycle. The lithium ion battery was subjected to multiple cycle charge and discharge tests according to the above method until the discharge capacity of the lithium ion secondary battery decayed to 80%, and the cycle number of the lithium ion battery was recorded.

[0217] The capacity retention rate of the battery after N cycles at 45℃ (%) = (the discharge capacity of the battery after the Nth cycle / the discharge capacity of the battery after the first cycle) x 100%.

[0218] 5. 60℃ storage performance test

[0219] The battery was charged at 0.33C to 4.4V, and then discharged at 0.33C to 2.5V at 25℃ constant temperature environment, and the discharge capacity D1 was tested. The battery was stored in a constant temperature environment at 60℃, and was taken out every 30 days for testing. The battery was cooled to 25℃ before each test, and then charged at 0.33C to 4.4V, and then discharged at 0.33C to 2.5V, and the discharge capacity was tested. The storage capacity retention rate decayed to 80% was calculated.

[0220] The capacity retention rate of the battery after N days of storage at 60℃ (%) = (the discharge capacity of the battery after N days of storage / the discharge capacity of the battery after the first storage) x 100%.

[0221] The battery preparation parameters and battery test results are shown in Table 1.

[0222] Comparing the data of the above examples 1, 61, 62, 63 with those of the comparative examples 1, 3, 4, 5, it can be found that when a cyclic organic base additive is added to the electrolyte, the cycle performance and storage performance of the battery are improved.

[0223] Comparing the data of the above example 1 with those of the comparative example 2, it can be found that under the condition of the presence of an organic base additive, reducing the content of EC within a certain range helps to improve the cycle performance and storage performance of the battery.

[0224] From examples 1, 55, 56, 57, it can be seen that by controlling the specific surface area of the positive electrode sheet to be 2cm 2 / g~10cm 2The contact area between the positive electrode sheet and the electrolyte can be reduced, the probability of EC oxidation and dehydrogenation can be reduced, the generation of protons can be reduced, the polarization of the lithium ion battery can not be too large, and the capacity of the lithium ion battery can not be affected.

[0225] As can be seen from Examples 1, 58, 59 and 60, by controlling the resistance of the positive electrode sheet containing the inorganic dielectric layer to be not higher than 1 Ω, in particular not higher than 0.5 Ω, the battery can have good kinetic performance and rate performance while improving the stability and safety performance of the battery system, thereby prolonging the cycle life of the battery.

[0226] 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, and equivalent components can be substituted therefor. In particular, the technical features mentioned in each embodiment 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 nonaqueous electrolyte solution comprising an organic solvent and an additive, the organic solvent comprising a first organic solvent, the first organic solvent being ethylene carbonate, wherein, The mass content of ethylene carbonate in the electrolyte is W1, W1 satisfies 0 < W1≤ 30%; the additive comprises a first additive, and the first additive is a cyclic organic base additive.

2. The non-aqueous electrolyte according to 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 (III), compound 4 of general formula (IV) or (IV’), and compound 5 of general formula (V), In general formula (I), 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 (III), 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 (IV), 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 (IV’), X 1 , X 3 are each independently C or N, and at least one of X 1 , X 3 is N, In general formula (IV) and (IV’), 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 are 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 are each independently selected from: nothing, C1-C6 alkylene, C2-C6 alkenylene, R 44 , R 45 , R 47 are each independently selected from hydrogen, halogen, C1-C6 alkyl, C1-C6 haloalkyl; In general formula (V), 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 each 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 (I), 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 (I), 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 in the C1-C3 alkyl group of 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 compound having the structure of the general formula (I) is selected from any one or more of the following compounds: Compound 1-1; Compound 1-2; Compound 1-3; Compounds 1-4; Compounds 1-5; Compounds 1-6; Compounds 1-7; Compounds 1-8; Compounds 1-9; Compounds 1-10; Compounds 1-11; Compound 1-12.

7. The nonaqueous electrolyte according to claim 2, in general formula (II), 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 compound having the structure of the general formula (II) is selected from any one or more of the following compounds: Compound 2-1; Compound 2-2; Compound 2-3; Compound 2-4; Compound 2-5; Compounds 2-6; Compounds 2-7; Compounds 2-8; Compound 2-9.

11. The nonaqueous electrolyte according to claim 2, wherein in the general formula (III), 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 nonaqueous electrolyte according to any one of claims 2 or 10 to 12, wherein in the general formula (III), R 32 , R 33 , R 34 , R 35 , R 36 , R 37 are each 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 the general formula (III) is selected from any one or more of the following compounds: Compound 3-1; Compound 3-2; Compound 3-3; Compound 3-4; Compound 3-5; Compound 3-6; Compound 3-7; Compound 3-8; Compound 3-9; Compound 3-10.

15. The nonaqueous electrolyte according to claim 2, wherein in the general formula (IV), X 1 is N, X 2 , X 3 are each independently C or N; optionally, X 2 is N; optionally, X 3 is C. In the general formula (IV), X 1 , X 3 are each N.

16. The non-aqueous electrolyte according to claim 2 or 15, wherein in the general formula (IV), 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 (IV’), 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 (IV) is (IV-1) : ###00013### wherein a, b, X 1 , X 2 , X 3 as defined in claim 2, 15 or 16; The general formula (IV) is (IV-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, wherein 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 of the general formula (IV) is selected from any one or more of the following compounds: Compound 4-1a; Compound 4-1; Compound 4-2; Compound 4-3; Compound 4-4; Compound 4-5; Compound 4-6.

20. The non-aqueous electrolyte according to claim 2, wherein in the general formula (V), d is 0 or 1.

21. The nonaqueous electrolyte according to claim 2 or 20, wherein each R 51 each is independently selected from the group consisting of hydrogen, halogen, C1-C4 alkyl, C3-C5 alkenyl, C3-C5 alkynyl, -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 of the general formula (V) is selected from any one or more of the following compounds: Compound 5-1; Compound 5-2; Compound 5-3; Compound 5-4; Compound 5-5; Compound 5-6; Compound 5-7; Compound 5-8.

23. The nonaqueous electrolyte of any one of claims 1-22, wherein, The mass proportion of the first additive in the non-aqueous electrolyte is W2, W2 satisfies 0.1%≤ W2≤ 20%, optionally 0.1%≤ W2≤ 10%, further optionally 1%≤ W2≤ 5%.

24. The non-aqueous electrolyte according to any one of claims 1-23, wherein the mass content of ethylene carbonate in the electrolyte is W1, W1 satisfies 0 < W1≤ 20%.

25. The non-aqueous electrolyte according to any one of claims 1-24, wherein the organic solvent further comprises a second organic solvent, and optionally, the second organic solvent comprises one or more of a chain carbonate other than a cyclic carbonate or ethylene carbonate.

26. The non-aqueous electrolyte according to any one of claims 1-25, 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.

27. A secondary battery comprising a positive electrode sheet, a negative electrode sheet, and an electrolyte, wherein The electrolyte is the non-aqueous electrolyte according to any one of claims 1-23.

28. The secondary battery of claim 27, wherein, The active specific surface area of the positive electrode sheet is A, where 0 < A < 20 cm 2 / g, optionally 2 cm 2 / g < A < 10 cm 2 / g.

29. The secondary battery according to claim 27 or 28, wherein The resistance R of the positive electrode sheet is greater than 0 and not higher than 1Ω, optionally 0 < R≤ 0.8Ω, further optionally 0 < R≤ 0.5Ω.

30. An electrically powered device comprising a secondary battery, wherein, The secondary battery comprises the secondary battery according to any one of claims 24-29.

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