Secondary battery and electric device

Abstract

The present application provides a secondary battery and an electric device. The secondary battery of the present application comprises a positive electrode sheet and a non-aqueous electrolyte. The positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on the surface of at least one side of the positive electrode current collector, the porosity of the positive electrode film layer being 10%-35%. The non-aqueous electrolyte comprises an electrolyte additive, the electrolyte additive including one or more of substituted or unsubstituted 5-12 membered aromatic heterocyclic organic base additives and substituted or unsubstituted 5-12 membered aliphatic heterocyclic organic base additives. The cycle life, storage performance, and energy density of the secondary battery of the present application are improved.

Description

Secondary battery and power consuming device

[0001] This application is based on and claims priority to CN application No. 202410953985.3, filed on July 16, 2024, the entire contents of which are incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of secondary batteries, in particular to a secondary battery and a power consuming device. BACKGROUND

[0003] In recent years, with the application range of secondary batteries becoming more and more extensive, secondary batteries are widely used in energy storage power supply systems such as hydropower, thermal power, wind power and solar power stations, and in many fields such as electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. Due to the great development of secondary batteries, higher requirements are put forward for their cycle performance, storage performance and energy density. SUMMARY

[0004] The present application is made in view of the above-mentioned problems, and aims to provide a secondary battery and a power consuming device, the cycle performance, storage performance and energy density of the secondary battery of the present application are simultaneously improved and enhanced.

[0005] In order to achieve the above-mentioned purpose, the first aspect of the present application provides a secondary battery, comprising a positive electrode sheet and a non-aqueous electrolyte, the positive electrode sheet comprises a positive electrode current collector and a positive electrode film layer located on at least one side surface of the positive electrode current collector, the porosity of the positive electrode film layer is 10%-35%, and the non-aqueous electrolyte comprises an electrolyte additive.

[0006] The electrolyte additive comprises one or more of a substituted or unsubstituted 5-12 membered aromatic heterocyclic organic base additive and a substituted or unsubstituted 5-12 membered aliphatic heterocyclic organic base additive.

[0007] If the porosity of the positive electrode film layer is too low, it is difficult to dry the water in the electrode sheet, and the residual water causes the electrolyte to decompose to generate R+(such as H + ), which further destroys or reduces the SEI film at the negative electrode, consumes the active lithium of the negative electrode, and deteriorates the cycle performance of the battery.

[0008] Therefore, by using the positive electrode film layer with the above-mentioned porosity range and the electrolyte additive, on the one hand, it is beneficial to dry and remove the water in the positive electrode sheet to reduce the generation of R+, while maintaining the compaction density of the positive electrode sheet, on the other hand, the electrolyte additive can capture R+, inhibit R+ from destroying or reducing the SEI film at the negative electrode, and reduce the consumption of the active lithium of the negative electrode, thereby improving the cycle performance, storage performance and energy density of the battery.

[0009] In any embodiment, the electrolyte additive comprises one or more of a compound of structural formula (I), a compound of structural formula (II), a compound of structural formula (III), a compound of structural formula (IV), and a compound of structural formula (V):

[0010] wherein, in structural formula (I), Y1and Y2are each independently selected from a C atom and a N atom, R1, R2, R3, R4, and R5are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 24 OH, -R 25 NR 26 R 27 , wherein R 24 and R 25 are each independently selected from a C0-C6alkylene group, a C2-C6alkenylene group, R 26 and R 27 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group, or R 26 , R 27 and the N atom form a 5-8 membered aliphatic heterocycle containing 2-4 heteroatoms, the heteroatoms including the N atom, the S atom, the P atom; or R2and / or R4are absent;

[0011] In structural formula (II), W1is selected from a C atom, a N atom, an O atom, and an S atom, W2is selected from a C atom and a N atom, R6, R7, R8, and R9are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C3-C8cycloalkyl group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 28 OH, -R 29 NR 30 R 31 ; wherein R 28 and R 29 are each independently selected from a C0-C6alkylene group, R 30 and R 31 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group;

[0012] In structural formula (III), A1, A2, A3, A4, and A5are each independently selected from a C atom and a N atom, R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 , and R 15each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 32 OH, -R 33 NR 34 R 35 ; wherein R 32 and R 33 each independently selected from a C0-C6alkylene group, R 34 and R 35 each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group; or, R 10 , R 10’ , R 11 and R 14 one or more groups are absent;

[0013] In structural formula (IV), X1, X2, X3and X4are each independently selected from a C atom and a N atom, a and b are each independently selected from an integer from 0 to 3, R 16 , R 17 and R 18 each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -OH, -NR 36 R 37 ; wherein R 36 and R 37 each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group; or, R 18 is absent;

[0014] In structural formula (V), V1, V2, V3and V4are each independently selected from a C atom and a N atom, d is selected from an integer from 0 to 3, R 19 , R 20 , R 21 , R 22 and R 23 each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -OH, -NR 38 R 39 ; wherein R 38 and R 39 each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group.

[0015] In any embodiment, the porosity of the positive electrode film layer is 18% to 27%.

[0016] In any embodiment, the positive electrode film layer comprises a positive electrode active material, the positive electrode active material comprises an inner core and a carbon coating layer coating the inner core.

[0017] In any embodiment, the carbon coating layer comprises sp2 hybridized carbon atoms.

[0018] In any embodiment, the carbon coating layer further comprises sp3 hybridized carbon atoms; and the molar ratio of the sp2 hybridized carbon atoms to the sp3 hybridized carbon atoms is ≥ 0.3, ≥ 0.5, or 0.5-10.

[0019] Therefore, by adopting the above range of the molar ratio of the sp2 hybridized carbon atoms to the sp3 hybridized carbon atoms, it is beneficial to appropriately reduce the number of active functional groups, improve the structural stability of the positive electrode active material, and further improve the storage performance and cycle performance of the battery.

[0020] In any embodiment, the mass percentage content of the carbon coating layer in the positive electrode active material is 0.8%-3.5% or 1.3%-2.5%.

[0021] Therefore, it is beneficial to optimize the morphology and structure of the positive electrode active material particles, improve the stability of the particle structure, improve the electrical conductivity of the positive electrode active material, and reduce the charge transport resistance.

[0022] In any embodiment, the positive electrode film layer comprises a positive electrode active material, the BET specific surface area of the positive electrode active material is 8-30 m 2 / g or 10-25 m 2 / g.

[0023] Therefore, by adopting the above range of the BET specific surface area of the positive electrode active material, on the one hand, it provides sufficient active specific surface area for lithium ion intercalation and deintercalation, is beneficial to the deintercalation of lithium ions, and improves the electrochemical performance such as capacity development and cycle performance of the battery; on the other hand, it reduces the contact between the positive electrode active material and the electrolyte, reduces the side reaction between the electrolyte and the positive electrode active material, and improves the cycle performance and storage performance of the battery.

[0024] In any embodiment, the positive electrode film layer comprises a positive electrode active material, the powder resistivity of the positive electrode active material is 10-200 Ω·cm or 10-100 Ω·cm.

[0025] In any embodiment, the inner core comprises one or more of lithium iron manganese phosphate, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium iron vanadium phosphate, lithium manganese vanadium phosphate, and lithium manganese iron vanadium phosphate.

[0026] In any embodiment, the mass percentage content of the electrolyte additive in the non-aqueous electrolyte is 0.05%-20% or 0.1%-10%.

[0027] Therefore, the above mass ratio range of the electrolyte additive is beneficial to fully consume R+ in the electrolyte, inhibit the damage of R+ to the negative electrode, and improve the cycle performance and storage performance of the battery. On the other hand, the electrolyte additive is not used in excess, which reduces the viscosity of the electrolyte, improves the electrical conductivity of the electrolyte, reduces the negative electrode impedance, and improves the cycle performance and storage performance of the battery.

[0028] In any embodiment, in the structural formula (I),

[0029] R1, R2, R3, R4 and R5 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, a hydroxyl C1-C4 alkyl group, -NH2, a di C1-C4 alkyl amine group, an amino C1-C4 alkyl group, a piperazinyl group; or, R2 and / or R4 is absent; or, 24 OH, -R 25 NR 26 R 27 ; wherein, R 24 and R 25 are each independently selected from a C0-C4 alkylene group, R 26 and R 27 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halogenated C1-C4 alkyl group, or R 26 , R 27 and the N atom form a 5-6 membered aliphatic heterocyclic ring containing 2 heteroatoms, the heteroatoms being N atoms; or, R2 and / or R4 is absent; or,

[0030] R1, R2, R3, R4 and R5 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, a hydroxyl C1-C4 alkyl group, -NH2, a di C1-C4 alkyl amine group, an amino C1-C4 alkyl group, a piperazinyl group; or, R2 and / or R4 is absent; or,

[0031] R1, R2, R3, R4 and R5 are each independently selected from a hydrogen atom, a F atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a t-butyl group, a methoxy group, an ethoxy group, an allyl group, a propargyl group, -OH, a hydroxyl methyl group, a hydroxyl ethyl group, -NH2, -N(CH3)2, -CH2NH2, or, R2 and / or R4 is absent; or,

[0032] R1, R2, R3, R4 and R5 are each independently selected from a hydrogen atom, a F atom, a methyl group, a t-butyl group, a methoxy group, a hydroxyl methyl group, -N(CH3)2, -CH2NH2, or, R2 and / or R4 is absent.

[0033] In any embodiment, in the structural formula (II),

[0034] R6, R7, R8and R9are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C3-C5cycloalkyl group, a C2-C4alkenyl group, a C2-C4alkynyl group, -R 28 OH, -R 29 NR 30 R 31 ; wherein R 28 and R 29 are each independently selected from a C0-C4alkylene group, R 30 and R 31 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group; or,

[0035] R6, R7, R8and R9are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C3-C5cycloalkyl group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, a hydroxyl C1-C4alkyl group, -NH2, a mono C1-C4alkyl amine group, a di C1-C4alkyl amine group, an amino C1-C4alkyl group; or,

[0036] R6, R7, R8and R9are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a methoxy group, an ethoxy group, a cyclopropyl group, a cyclobutyl group, an allyl group, a propargyl group, -OH, a hydroxyl methyl group, a hydroxyl ethyl group, -NH2, -NHCH3, -N(CH3)2, -CH2NH2; or,

[0037] R6, R7, R8and R9are each independently selected from a hydrogen atom, a fluorine atom, a methyl group, a cyclopropyl group, an allyl group, a hydroxyl methyl group, -NHCH3.

[0038] In any embodiment, in the structural formula (III),

[0039] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -R 32 OH, -R 33 NR 34 R 35 ; wherein R 32 and R 33 are each independently selected from a C0-C4alkylene group, R34 and R 35 each independently is selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halogenated C1-C4 alkyl group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or,

[0040] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 each independently is selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, a hydroxy C1-C4 alkyl group, -NH2, a mono C1-C4 alkyl amine group, a di C1-C4 alkyl amine group, an amino C1-C4 alkyl group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or,

[0041] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 each independently is selected from a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a methoxy group, an allyl group, a propargyl group, -OH, -NH2, -CH2NH2, -N(CH3)2; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or,

[0042] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 each independently is selected from a hydrogen atom, a methyl group, a methoxy group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent.

[0043] In any embodiment, in the structural formula (IV),

[0044] R 16 , R 17 and R 18 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NR 36 R 37 ; wherein R 36 and R 37 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halogenated C1-C4 alkyl group; or, R 18 is absent; or,

[0045] R 16 , R 17 and R 18 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NH2, a mono C1-C4 alkyl amine group, a di C1-C4 alkyl amine group; or, R 18 is absent; or,

[0046] R 16 , R 17 and R 18 are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a methoxy group, an ethoxy group, an allyl group, a propargyl group, -OH, -NH2, -NHCH3, -N(CH3)2; or, R 18 is absent; or,

[0047] R 16 , R 17 and R 18 are each independently selected from a hydrogen atom, a methyl group, -N(CH3)2; or, R 18 is absent.

[0048] In any embodiment, in the structural formula (V), R

[0049] R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NR 38 R 39 ; wherein R 38 and R 39 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halogenated C1-C4 alkyl group; or,

[0050] R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NH2, a mono C1-C4 alkylamino group, a di C1-C4 alkylamino group; or,

[0051] R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a t-butyl group, a methoxy group, an ethoxy group, an allyl group, a propargyl group, -OH, -NH2, -NHCH3, -N(CH3)2; or,

[0052] R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an i-propyl group, a t-butyl group.

[0053] In any embodiment, in the structural formula (I), 0, 1 or 2 of Y1and Y2are N atoms; and / or,

[0054] In the structural formula (II), at least one of W1and W2is a N atom; and / or,

[0055] In the structural formula (III), at least one of A1, A2, A3, A4and A5is a N atom; and / or,

[0056] In the structural formula (IV), at least one of X1, X2, X3and X4is a N atom; and / or,

[0057] In the structural formula (V), at least one of V1, V2, V3and V4is a N atom.

[0058] In any embodiment, in the structural formula (I), 0, 1 or 2 of Y1and Y2are N atoms; and / or,

[0059] In the structural formula (II), at least one of W1and W2is a N atom; and / or,

[0060] In the structural formula (III), 1, 2, 3 or 4 of A1, A2, A3, A4and A5are N atoms; and / or,

[0061] In the structural formula (IV), 2 or 3 of X1, X2, X3 and X4 are N atoms; and / or,

[0062] In the structural formula (V), 1, 2 or 3 of V1, V2, V3 and V4 are N atoms.

[0063] In any embodiment, the compound represented by the structural formula (I) is selected from at least one of the following compounds:

[0064] In any embodiment, the compound represented by the structural formula (II) is selected from at least one of the following compounds:

[0065] In any embodiment, the compound represented by the structural formula (III) is selected from at least one of the following compounds:

[0066] In any embodiment, the compound represented by the structural formula (IV) is selected from at least one of the following compounds:

[0067] In any embodiment, the compound represented by the structural formula (V) is selected from at least one of the following compounds:

[0068] The second aspect of the present application also provides a power utilization device comprising the secondary battery of the first aspect of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0069] FIG. 1 is a schematic view of a battery cell according to an embodiment of the present application.

[0070] FIG. 2 is an exploded view of the battery cell according to an embodiment of the present application shown in FIG. 1.

[0071] FIG. 3 is a schematic view of a battery module according to an embodiment of the present application.

[0072] FIG. 4 is a schematic view of a battery pack according to an embodiment of the present application.

[0073] FIG. 5 is an exploded view of the battery pack according to an embodiment of the present application shown in FIG. 4.

[0074] FIG. 6 is a schematic view of a power utilization device using the battery cell according to an embodiment of the present application as a power source.

[0075] BRIEF DESCRIPTION OF DRAWINGS DETAILED DESCRIPTION

[0076] Hereinafter, specific embodiments of the negative electrode active material and the method for manufacturing the same, the positive electrode sheet, the negative electrode sheet, the battery cell, the battery module, the battery pack, and the power tool of the present application will be described 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 known well, repeated description of substantially identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter recited in the claims.

[0077] The ranges disclosed herein are defined by their lower and upper limits. Ranges can be inclusive or exclusive of their endpoints, and are arbitrarily combinable. For example, if a range is listed as 60-120 and 80-110, it is understood that 60-110 and 80-120 are also expressly stated. Also, where a minimum range value of 1 and 2 is listed, and a maximum range value of 3, 4, and 5 is listed, then the following ranges are all expressly stated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, a numerical range "a-b" indicates "any and all subcombinations of values between the lower value a and the upper value b," where a and b are both real numbers. For example, the numerical range "0-5" indicates 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 of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0078] If not specifically stated, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions.

[0079] If not specifically stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0080] If not otherwise specifically defined, all processes of the application can be carried out in any suitable order, preferably in the order as described. For example, a process comprising steps (a) and (b) means that the process can comprise steps (a) and (b) in this order, but also steps (b) and (a) in this order. For example, a process which can further comprise step (c) means that step (c) can be added to the process in any order, for example, the process can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0081] The term "alkyl" denotes a straight-chain or branched-chain hydrocarbon group, obtained by removal of one hydrogen atom from a hydrocarbon, for example "Ci-C6-alkyl", "Ci-C4-alkyl", "Ci-C3-alkyl" and the like. Particular examples include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, 2-methylbutyl, neopentyl, 1-ethylpropyl, n-hexyl, isohexyl, 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.

[0082] The term "alkylene" denotes a divalent group, obtained by removal of one hydrogen atom from an alkyl group, which consists solely of carbon and hydrogen atoms, contains no groups other than alkyl groups, and is attached to the rest of the molecule by two single bonds, including, but not limited to, methylene, ethylene, The term "alkylene" denotes a divalent group, obtained by removal of one hydrogen atom from an alkyl group, which consists solely of carbon and hydrogen atoms, contains no groups other than alkyl groups, and is attached to the rest of the molecule by two single bonds, including, but not limited to, methylene, ethylene,

[0083] The term "alkenyl" denotes a straight-chain or branched-chain hydrocarbon group, which contains at least one carbon-carbon double bond, including, for example, "C2-C6-alkenyl", "C2-C4-alkenyl" and the like. Particular examples include, but are not limited to, ethenyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 1,3-buten- dienyl, 1-pentenyl, 2-pentenyl, 3-pentenyl, 1,3-pentadienyl, 1,4-pentadienyl, 1-hexenyl, 2-hexenyl, 3-hexenyl, 1,4-hexadienyl and the like.

[0084] The term "alkenylene" denotes a divalent group, obtained by removal of one hydrogen atom from an alkenyl group, which consists solely of carbon and hydrogen atoms, contains at least one double bond, and is attached to the rest of the molecule by two single bonds, including, but not limited to etc. Alkenyl groups are defined as above. For example, "C2-C6alkenylene" refers to a divalent straight or branched chain hydrocarbon group containing from 2 to 6 carbon atoms and having at least one carbon-carbon double bond (>C=C<), C2-C4alkenylene, C2-C3alkenylene, etc.

[0085] The term "alkynyl" refers to straight or branched chain hydrocarbon groups containing at least one carbon-carbon triple bond. Included are, for example, "C2-C6alkynyl", "C2-C4alkynyl", 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.

[0086] The term "heterocyclyl" or "heterocycle" refers to a saturated or partially saturated, monocyclic or polycyclic (such as bicyclic) non-aromatic ring structure whose ring atoms are composed of carbon atoms and at least one (e.g., 1, 2, or 3) heteroatom selected from nitrogen, oxygen, and sulfur. The heterocyclyl group can be attached to the rest of the molecule through any one of the ring atoms, if valence requirements permit. The term "5-6 membered nitrogen-containing heterocycle" as used 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.

[0087] The term "cycloalkyl" refers to monocyclic or polycyclic groups containing saturated or partially unsaturated (e.g., containing 1 or 2 double bonds) rings. "Monocycloalkyl" preferably refers to 3-10 membered monocycloalkyl groups, more preferably 3-8 membered monocycloalkyl groups, such as 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 one or more (e.g., 1-3) additional carbon atoms forming an alkylene bridge (i.e., -(CH2) t"spirocycloalkyl" refers to a bicyclic group formed by two cycloalkyl groups sharing one carbon atom. Polycycloalkyl groups can be 5-18 membered, preferably 6-15 membered, more preferably 6-12 membered. The polycycloalkyl group is preferably a bicyclic cycloalkyl group.

[0088] The term "aromatic ring" includes all-carbon monocyclic rings having a conjugated pi-electron system 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, in particular 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms, and which contains one or more (e.g., 1, 2, 3, or 4) heteroatoms (e.g., oxygen, nitrogen, or sulfur) which can be the same or different.

[0089] The term "alkoxy" refers to a group having the structure "alkyl-O-" wherein alkyl is as defined above. Examples include C1-C6alkoxy, C1-C4alkoxy, C1-C3alkoxy, or C1-C2alkoxy, etc. Common alkoxy groups include, but are not limited to, methoxy, ethoxy, n-propyloxy, iso-propyloxy, n-butyloxy, iso-butyloxy, t-butyloxy, pentyloxy, hexyloxy, etc. Alkoxy groups in the present application are optionally substituted with one or more substituents described herein.

[0090] The term "halo" or "halogen" is defined to include F, Cl, Br, or I.

[0091] The term "substituted" means that one or more (e.g., 1, 2, 3, 4, or 5) hydrogens on the designated compound or structural fragment are replaced with a substituent, provided that the designated atom's normal valence is not exceeded and that the substitution results in a stable compound.

[0092] As used herein, the term "one or more" means 1 or more than 1, e.g., 2, 3, 4, 5, or 10, under reasonable conditions.

[0093] The term "independently" means that at least two groups (or ring systems) in a structure that have the same or similar range of values can have the same or different meaning in a particular instance. 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.

[0094] Unless specified, the point of attachment of a substituent as used herein can come from any suitable position of the substituent.

[0095] [Battery cell]

[0096] Battery cell, also known as rechargeable battery or storage battery, refers to the battery that can be activated by charging after discharging to continue to use.

[0097] Generally, the battery cell includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte. During the charging and discharging process of the battery, active ions (such as lithium ions) 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 the short circuit of the positive and negative electrodes, and at the same time to 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.

[0098] One embodiment of the present application provides a secondary battery, comprising a positive electrode sheet and a non-aqueous electrolyte, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer on at least one side surface of the positive electrode current collector, the porosity of the positive electrode film layer being 10%-35% (for example, 12%, 15%, 18%, 20%, 22%, 25%, 27%, 30%, 32%, 35% or a range consisting of any of the above values), and the non-aqueous electrolyte comprising an electrolyte additive;

[0099] The electrolyte additive comprises one or more of a substituted or unsubstituted 5-12 membered aromatic heterocyclic organic base additive, a substituted or unsubstituted 5-12 membered aliphatic heterocyclic organic base additive.

[0100] If the porosity of the positive electrode film layer is too low, it is difficult to dry the water in the electrode sheet, and the residual water causes the electrolyte to decompose to generate R+ (for example, H + ), which further destroys or reduces the SEI film at the negative electrode, consumes the active lithium of the negative electrode, and deteriorates the cycle performance of the battery.

[0101] Although the mechanism is not clear, the present applicant has unexpectedly found that by using the positive electrode film layer with the above-mentioned porosity range and the electrolyte additive, on the one hand, it is beneficial to dry and remove the water in the positive electrode sheet to reduce the generation of R+, while maintaining the compaction density of the positive electrode sheet, on the other hand, the electrolyte additive can capture R+, inhibit R+ from destroying or reducing the SEI film at the negative electrode, reduce the consumption of the active lithium of the negative electrode, thereby improving the cycle performance, storage performance and energy density of the battery.

[0102] In some embodiments, the electrolyte additive comprises one or more of a compound of structural formula (I), a compound of structural formula (II), a compound of structural formula (III), a compound of structural formula (IV), and a compound of structural formula (V):

[0103] wherein, in structural formula (I), Y1and Y2are each independently selected from a C atom and an N atom, R1, R2, R3, R4, and R5are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 24 OH, -R 25 NR 26 R 27 , wherein R 24 and R 25 are each independently selected from a C0-C6alkylene group, a C2-C6alkenylene group, R 26 and R 27 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group, or R 26 , R 27 and the N atom form a 5-8 membered aliphatic heterocycle containing 2-4 heteroatoms, the heteroatoms including the N atom, the S atom, the P atom; or R2and / or R4are absent;

[0104] wherein, in structural formula (II), W1is selected from a C atom, an N atom, an O atom, and an S atom, W2is selected from a C atom and an N atom, R6, R7, R8, and R9are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C3-C8cycloalkyl group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 28 OH, -R 29 NR 30 R 31 ; wherein R 28 and R 29 are each independently selected from a C0-C6alkylene group, R 30 and R 31 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group;

[0105] wherein, in structural formula (III), A1, A2, A3, A4, and A5are each independently selected from a C atom and an N atom, R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 , and R 15each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -OH, -NR 32 OH, -R 33 NR 34 R 35 ; wherein R 32 and R 33 are each independently selected from a C0-C6alkylene group, R 34 and R 35 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a haloC1-C6alkyl group; or, R 10 , R 10’ , R 11 and R 14 are absent;

[0106] In Structural Formula (IV), X1, X2, X3and X4are each independently selected from a C atom and a N atom, a and b are each independently selected from an integer from 0 to 3, R 16 , R 17 and R 18 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -OH, -NR 36 R 37 ; wherein R 36 and R 37 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a haloC1-C6alkyl group; or, R 18 is absent;

[0107] In Structural Formula (V), V1, V2, V3and V4are each independently selected from a C atom and a N atom, d is selected from an integer from 0 to 3, R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -OH, -NR 38 R 39 ; wherein R 38 and R 39 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a haloC1-C6alkyl group.

[0108] In some embodiments, the porosity of the positive electrode film layer is 18% to 27%.

[0109] In the present application, the porosity of the positive electrode film layer can be tested by conventional methods in the art. For example, it can be tested by using a full-automatic true density tester in combination with the instrument instruction, or it can be tested according to the method in the national standard GB / T 24586-2009.

[0110] In some embodiments, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises an inner core and a carbon coating layer coating the inner core.

[0111] In some embodiments, the carbon coating layer comprises sp2 hybridized carbon atoms.

[0112] In some embodiments, the carbon coating layer further comprises sp3 hybridized carbon atoms; and the molar ratio of the sp2 hybridized carbon atoms to the sp3 hybridized carbon atoms is ≥ 0.3, ≥ 0.5, or 0.5-10, for example, 0.3, 0.4, 0.5, 0.7, 0.8, 1, 1.4, 1.8, 2, 2.5, 3, 4, 5, 6, 7, 8, 9, 10, or a range consisting of any of the aforementioned numerical values.

[0113] Therefore, by using the above-mentioned molar ratio range of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms, it is beneficial to appropriately reduce the number of active functional groups, improve the structural stability of the positive electrode active material, and further improve the storage performance and cycle performance of the battery.

[0114] In the present application, the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer can be tested by conventional methods in the art. For example, the two peak components of sp2 and sp3 can be determined by XPS, and the peaks can be fitted by applying XPX-Peak software; the bond length of sp3 is longer than that of sp2, the binding energy of sp3 is 285.2±0.1 eV, and the binding energy of sp2 is 284.4±0.1 eV; the areas occupied by sp2 and sp3 hybridized carbon are fitted according to the Lorentz-Gaussian function, and the molar ratio of sp2 hybridized carbon to sp3 hybridized carbon is quantitatively calculated according to the proportion of the area of sp2 to the total area of sp3 peak.

[0115] In some embodiments, the mass percentage content of the carbon coating layer in the positive electrode active material is 0.8%-3.5% or 1.3%-2.5%, for example, 0.8%, 1%, 1.1%, 1.3%, 1.5%, 1.8%, 2%, 2.2%, 2.5%, 2.7%, 3%, 3.1%, 3.3%, 3.5%, or a range consisting of any of the aforementioned numerical values.

[0116] Therefore, it is beneficial to optimize the morphology and structure of the positive electrode active material particles, improve the stability of the particle structure, improve the electrical conductivity of the positive electrode active material, and reduce the charge transport resistance.

[0117] In the present application, the mass percentage of the carbon coating layer in the positive electrode active material can be tested by conventional methods in the art. For example, the mass percentage of carbon element in the positive electrode active material can be tested by a carbon-sulfur analyzer.

[0118] In some embodiments, the positive electrode film layer comprises a positive electrode active material, and the BET specific surface area of the positive electrode active material is 8-30 m 2 / g or 10-25 m 2 / g, for example, 8 m 2 / g, 9 m 2 / g, 10 m 2 / g, 12 m 2 / g, 15 m 2 / g, 18 m 2 / g, 20 m 2 / g, 21 m 2 / g, 23 m 2 / g, 25 m 2 / g, 27 m 2 / g, 28 m 2 / g, 30 m 2 / g or a range composed of any of the above values.

[0119] Therefore, by using the positive electrode active material with the above range of BET specific surface area, on the one hand, sufficient active specific surface area is provided for lithium ion intercalation and deintercalation, which is beneficial for lithium ion deintercalation, improves the capacity performance, cycle performance and other electrochemical properties of the battery, on the other hand, the contact between the positive electrode active material and the electrolyte is reduced, the side reaction between the electrolyte and the positive electrode active material is reduced, and the cycle performance and storage performance of the battery are improved.

[0120] In the present application, the BET specific surface area of the positive electrode active material can be tested by conventional methods in the art. For example, it can be tested according to GB / T 19587-2004 national standard. Specifically, the sample to be tested can be loaded into a sample tube, and the initial mass is recorded; then it is loaded into a specific surface and pore size tester, and degassing is started. The sample to be tested is heated to 200℃ and kept for 2h, and the mass of the sample to be tested after degassing is recorded; then the degassed sample to be tested is reloaded into the specific surface and pore size tester, and liquid nitrogen is poured in for BET testing. After the test is completed, the BET specific surface area is read from the test results.

[0121] In some embodiments, the positive electrode film layer comprises a positive electrode active material, and the positive electrode active material has a powder resistivity of 10-200 Ω·cm or 10-100 Ω·cm, for example, 10 Ω·cm, 15 Ω·cm, 20 Ω·cm, 22 Ω·cm, 25 Ω·cm, 27 Ω·cm, 30 Ω·cm, 35 Ω·cm, 36 Ω·cm, 37 Ω·cm, 40 Ω·cm, 45 Ω·cm, 50 Ω·cm, 57 Ω·cm, 60 Ω·cm, 65 Ω·cm, 70 Ω·cm, 75 Ω·cm, 76 Ω·cm, 81 Ω·cm, 89 Ω·cm, or a range defined by any of the above values.

[0122] In the present application, the powder resistivity of the positive electrode active material can be tested by conventional methods in the art. For example, a powder resistance and compaction density tester is used to take the positive electrode active material powder and press it into a thin sheet with a mold, which is then placed in the device, and the test pressure and holding time are configured to obtain the powder resistivity of the positive electrode active material.

[0123] In some embodiments, the core comprises one or more of lithium iron manganese phosphate, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium vanadium iron phosphate, lithium vanadium manganese phosphate, lithium manganese vanadium phosphate.

[0124] In some embodiments, the mass percentage of the electrolyte additive in the non-aqueous electrolyte is 0.05%-20% or 0.1%-10%, for example, 0.05%, 0.08%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.7%, 2%, 2.5%, 3%, 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, or a range defined by any of the above values.

[0125] Thus, the above mass percentage range of the electrolyte additive, on the one hand, is conducive to the electrolyte additive fully consuming R+ in the electrolyte, inhibiting the damage of R+ to the negative electrode, and improving the cycle performance and storage performance of the battery, and on the other hand, the use of the electrolyte additive is not excessive, which reduces the viscosity of the electrolyte, improves the electrical conductivity of the electrolyte, reduces the negative electrode impedance, and improves the cycle performance and storage performance of the battery.

[0126] In some embodiments, in the structural formula (I),

[0127] R1, R2, R3, R4, and R5 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -R 24 OH, -R 25 NR 26 R27 ; wherein R 24 and R 25 are each independently selected from C0-C4alkylene, R 26 and R 27 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group, or R 26 , R 27 form a 5-6 membered aliphatic heterocycle containing 2 heteroatoms, the heteroatoms being N atoms; or, R2and / or R4are absent; or,

[0128] R1, R2, R3, R4and R5are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, a hydroxyl C1-C4alkyl group, -NH2, a di C1-C4alkyl amine group, an amino C1-C4alkyl group, a piperazinyl group; or, R2and / or R4are absent; or,

[0129] R1, R2, R3, R4and R5are each independently selected from a hydrogen atom, a F atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a tert-butyl group, a methoxy group, an ethoxy group, an allyl group, a propargyl group, -OH, a hydroxyl methyl group, a hydroxyl ethyl group, -NH2, -N(CH3)2, -CH2NH2, or, R2and / or R4are absent; or,

[0130] R1, R2, R3, R4and R5are each independently selected from a hydrogen atom, a F atom, a methyl group, a tert-butyl group, a methoxy group, a hydroxyl methyl group, -N(CH3)2, -CH2NH2, or, R2and / or R4are absent.

[0131] In some embodiments, in the structural formula (II),

[0132] R6, R7, R8and R9are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C3-C5cycloalkyl group, a C2-C4alkenyl group, a C2-C4alkynyl group, -R 28 OH, -R 29 NR 30 R 31 ; wherein R 28 and R 29 are each independently selected from C0-C4alkylene, R 30 and R 31 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group; or,

[0133] R6, R7, R8and R9are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C3-C5cycloalkyl group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, a hydroxy C1-C4alkyl group, -NH2, a mono C1-C4alkylamino group, a di C1-C4alkylamino group, an amino C1-C4alkyl group; or,

[0134] R6, R7, R8and R9are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a methoxy group, an ethoxy group, a cyclopropyl group, a cyclobutyl group, an allyl group, a propargyl group, -OH, a hydroxymethyl group, a hydroxyethyl group, -NH2, -NHCH3, -N(CH3)2, -CH2NH2; or,

[0135] R6, R7, R8and R9are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a methyl group, a cyclopropyl group, an allyl group, a hydroxymethyl group, -NHCH3.

[0136] In some embodiments, the structural formula (III) is:

[0137] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OR 32 , -OR 33 , -NR 34 R 35 ; wherein R 32 and R 33 are each independently selected from a C0-C4alkylene group, R 34 and R 35 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halo C1-C4alkyl group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or,

[0138] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, a hydroxy C1-C4 alkyl group, -NH2, a mono C1-C4 alkylamino group, a di C1-C4 alkylamino group, an amino C1-C4 alkyl group; or, one or more of the groups of R 10 , R 10’ , R 11 , and R 14 is absent; or,

[0139] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 , and R 15 each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a methoxy group, an allyl group, a propargyl group, -OH, -NH2, -CH2NH2, -N(CH3)2; or, one or more of the groups of R 10 , R 10’ , R 11 , and R 14 is absent; or,

[0140] R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 , and R 15 each independently selected from the group consisting of a hydrogen atom, a methyl group, a methoxy group; or, one or more of the groups of R 10 , R 10’ , R 11 , and R 14 is absent.

[0141] In some embodiments, in the structural formula (IV),

[0142] R 16 , R 17 , and R 18 each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NR 36 R 37 ; wherein R 36 and R 37 each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halo C1-C4 alkyl group; or, R 18 is absent; or,

[0143] R16 , R 17 , and R 18 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NH2, a mono C1-C4 alkylamino group, a di C1-C4 alkylamino group; or, R 18 is absent; or,

[0144] R 16 , R 17 , and R 18 are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a methoxy group, an ethoxy group, an allyl group, a propargyl group, -OH, -NH2, -NHCH3, -N(CH3)2; or, R 18 is absent; or,

[0145] R 16 , R 17 , and R 18 are each independently selected from a hydrogen atom, a methyl group, -N(CH3)2; or, R 18 is absent.

[0146] In some embodiments, in the structural formula (V),

[0147] R 19 , R 20 , R 21 , R 22 , and R 23 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NR 38 R 39 ; wherein R 38 and R 39 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halogenated C1-C4 alkyl group; or,

[0148] R 19 , R 20 , R 21 , R 22 , and R 23 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, -NH2, a mono C1-C4 alkylamino group, a di C1-C4 alkylamino group; or,

[0149] R 19 , R 20 , R 21 , R 22 , and R23 each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a t-butyl group, a methoxy group, an ethoxy group, an allyl group, a propargyl group, -OH, -NH2, -NHCH3, -N(CH3)2; or,

[0150] R 19 , R 20 , R 21 , R 22 and R 23 each independently selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an i-propyl group, a t-butyl group.

[0151] In some embodiments, in the structural formula (I), 0, 1 or 2 of Y1and Y2are N atoms; and / or,

[0152] In the structural formula (II), at least one of W1and W2is a N atom; and / or,

[0153] In the structural formula (III), at least one of A1, A2, A3, A4and A5is a N atom; and / or,

[0154] In the structural formula (IV), at least one of X1, X2, X3and X4is a N atom; and / or,

[0155] In the structural formula (V), at least one of V1, V2, V3and V4is a N atom.

[0156] In some embodiments, in the structural formula (I), 0, 1 or 2 of Y1and Y2are N atoms; and / or,

[0157] In the structural formula (II), at least one of W1and W2is a N atom; and / or,

[0158] In the structural formula (III), 1, 2, 3 or 4 of A1, A2, A3, A4and A5are N atoms; and / or,

[0159] In the structural formula (IV), 2 or 3 of X1, X2, X3and X4are N atoms; and / or,

[0160] In the structural formula (V), 1, 2 or 3 of V1, V2, V3and V4are N atoms.

[0161] In some embodiments, the compound represented by the structural formula (I) is selected from at least one of the following compounds:

[0162] In some embodiments, the compound represented by the structural formula (II) is selected from at least one of the following compounds:

[0163] In some embodiments, the compound of structural formula (III) is selected from at least one of the following compounds:

[0164] In some embodiments, the compound of structural formula (IV) is selected from at least one of the following compounds:

[0165] In some embodiments, the compound of structural formula (V) is selected from at least one of the following compounds:

[0166] Table 1 Electrolyte additives

[0167] In some embodiments, the core comprises Li 1+x Mn 1-y A y PO4, x is any number in the range of -0.100 to 0.100, y is any number in the range of 0 to 0.500, A comprises one or more elements selected from Zn, Al, Na, K, Mg, Mo, W, Ti, V, Zr, Fe, Ni, Co, Ga, Sn, Sb, Nb, and Ge, and optionally comprises one or more elements selected from Fe, Ti, V, Ni, Co, and Mg.

[0168] In some embodiments, the carbon coating layer can be prepared by conventional methods in the art, or by the following method:

[0169] providing a core material;

[0170] mixing the core material with a carbon source and a solvent to obtain a mixture;

[0171] sintering the mixture under a protective atmosphere to obtain a positive electrode active material of the carbon-coated core material.

[0172] In some embodiments, the carbon source can be selected from one or more of glucose, fructose, sucrose, starch, stevioside, lactose, xylose, cellulose, maltose, chitin, D-glucosamine, glucosamine sulfate, fructose phosphate, glucose-6-phosphate, N-acetylglucosamine, peptidoglycan, polyacrylate, polyethylene glycol, citric acid, malic acid, propylene, polyethylene glycol, polypropylene, polyacrylamide, lithium polyacrylate, polyvinyl alcohol, cyclodextrin, polyvinyl butyral, polystyrene, and graphite.

[0173] In some embodiments, the porosity of the positive electrode film layer can be controlled by the roller pressure during cold pressing of the positive electrode tab, for example, increasing the roller pressure, the porosity of the positive electrode film layer becomes smaller.

[0174] In some embodiments, the BET specific surface area of the positive electrode active material can be achieved by adjusting the type, amount of carbon source and sintering temperature.

[0175] In some embodiments, the molar ratio of sp2 hybridized carbon atoms to sp3 hybridized carbon atoms in the carbon coating layer can be controlled by sintering conditions (e.g., sintering temperature and sintering time).

[0176] [Positive electrode tab]

[0177] 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 active material in this application, the molar content of Li is the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to the battery system, the molar content of Li will change after charging and discharging cycles.

[0178] In the enumeration of the positive electrode active material in this application, the molar content of O is only the theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual molar content of O will fluctuate.

[0179] As an example, the positive electrode current collector has two opposite surfaces in the thickness direction of itself, and the positive electrode film layer is arranged on any one or both of the two opposite surfaces of the positive electrode current collector.

[0180] In some embodiments, the positive electrode current collector can adopt 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.).

[0181] In some embodiments, the positive active material can employ a positive active material for a battery known in the art. As an example, the positive active material can include at least one of a lithium-containing phosphate of an olivine structure, a lithium transition metal oxide, and a modified compound of each thereof. However, the present application is not limited to these materials, and other conventional materials that can be used as a positive active material for a battery can also be used. These positive active materials can be used alone only or in combination of two or more. Among them, examples of the lithium transition metal oxide can include, but are not limited to, lithium cobalt oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2(also referred to as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2(also referred to as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2(also referred to as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2(also referred to as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2(also referred to as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05 O2), and a modified compound thereof, etc. Examples of the lithium-containing phosphate of an olivine structure can include, but are not limited to, at least one of lithium iron phosphate (e.g., LiFePO4(also referred to as LFP)), a composite of lithium iron phosphate and carbon, lithium manganese phosphate (e.g., LiMnPO4), a composite of lithium manganese phosphate and carbon, lithium manganese iron phosphate, and a composite of lithium manganese iron phosphate and carbon.

[0182] In some embodiments, the positive electrode film layer can further optionally include a binder. As an example, the binder can include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a vinylidene-fluoride-tetrafluoroethylene-propylene terpolymer, a vinylidene-fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, a tetrafluoroethylene-hexafluoropropylene copolymer, and a fluorine-containing acrylate resin.

[0183] In some embodiments, the positive electrode film layer can also optionally include 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.

[0184] 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 drying, cold-pressing, or the like to obtain the positive electrode tab.

[0185] [Negative electrode tab]

[0186] The negative electrode tab includes a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector, the negative electrode film layer including a negative electrode active material.

[0187] 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 surfaces of the negative electrode current collector.

[0188] In some embodiments, the negative electrode current collector can employ a metal foil or a composite current collector. As a metal foil, for example, 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.).

[0189] In some embodiments, the negative electrode active material can employ a negative electrode active material known in the art for use in a battery. As an example, the negative electrode active material can include at least one of artificial graphite, natural graphite, soft carbon, hard carbon, silicon-based material, tin-based material, 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 electrode active material for a battery can also be used. These negative electrode active materials can be used alone or in combination of two or more.

[0190] In some embodiments, the negative film layer can further optionally include a binder. As an example, the binder can be selected from at least one of styrene butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0191] In some embodiments, the negative film layer can further optionally include a conductive agent. As an example, the conductive agent can be selected from at least one of super-P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0192] In some embodiments, the negative film layer can further optionally include other auxiliary agents, such as thickening agents (e.g., sodium carboxymethyl cellulose (CMC-Na), etc.

[0193] In some embodiments, the negative electrode sheet can be prepared by dispersing the above-mentioned 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 after processes such as drying, cold pressing, etc., the negative electrode sheet can be obtained.

[0194] [Electrolyte]

[0195] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. The type of electrolyte is not specifically limited in the present application and can be selected as needed.

[0196] In some embodiments, the electrolyte is in a liquid state and includes an electrolyte salt and a solvent.

[0197] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoroarsenate, lithium bisfluorosulfonylimide, lithium bis-trifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorobisoxalate borate, lithium bisoxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorodioxalate phosphate.

[0198] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, methyl ethyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0199] In some embodiments, the electrolyte solution can optionally further include other additives. As an example, the additives can include negative electrode film-forming additives, positive electrode film-forming additives, and can further include additives capable of improving certain properties of the battery, such as additives capable of improving overcharge performance of the battery, additives capable of improving high-temperature or low-temperature performance of the battery, and the like.

[0200] [Separator]

[0201] In some embodiments, a separator is further included in the battery cell. The type of separator is not particularly limited in the present application, and any known porous structure separator having good chemical stability and mechanical stability can be used.

[0202] In some embodiments, the material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator can be a single layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the respective layers can be the same or different, and are not particularly limited.

[0203] In some embodiments, the positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly through a winding process or a stacking process.

[0204] In some embodiments, the battery cell can include an outer package. The outer package can be used to package the electrode assembly and the electrolyte solution described above.

[0205] In some embodiments, the outer package of the battery cell can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, and the like. The outer package of the battery cell can also be a soft package, such as a pouch-type soft package. The material of the soft package can be plastic, and as plastic, polypropylene, polybutylene terephthalate, polybutylene succinate, and the like can be listed.

[0206] The shape of the 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 battery cell 5 having a square structure as an example.

[0207] In some embodiments, referring to FIG. 2, the outer package can include a housing 51 and a cover plate 53. The housing 51 can include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover plate 53 can be provided on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet, and the separator can be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged in the receiving cavity. The electrolyte solution is impregnated in the electrode assembly 52. The number of electrode assemblies 52 included in the battery cell 5 can be one or more, and can be selected by a person skilled in the art according to specific actual needs.

[0208] In some embodiments, the battery cell can be assembled into a battery module, and the number of battery cells contained in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0209] FIG. 3 is a battery module 4 as an example. Referring to FIG. 3, in the battery module 4, a plurality of battery cells 5 can be arranged in sequence along the length direction of the battery module 4. Of course, other arbitrary arrangements can also be used. Further, the plurality of battery cells 5 can be fixed by fasteners.

[0210] Optionally, the battery module 4 can further include a housing having an accommodation space, and the plurality of battery cells 5 can be accommodated in the accommodation space.

[0211] In some embodiments, the above-mentioned battery module can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0212] 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.

[0213] In addition, the present application also provides a power utilization device, which includes at least one of the battery cell, the battery module, or the battery pack provided by the present application. The battery cell, the battery module, or the battery pack can be used as a power supply of the power utilization device, or can be used as an energy storage unit of the power utilization device. The power utilization device can include a mobile device (such as a mobile phone, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), an electric train, a ship and a satellite, an energy storage system, etc., but is not limited thereto.

[0214] As the power utilization device, the battery cell, the battery module, or the battery pack can be selected according to the use requirements thereof.

[0215] 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 high power and high energy density requirements of the battery cell for the power utilization device, the battery pack or the battery module can be used.

[0216] [Embodiment]

[0217] Hereinafter, the examples of the present application will be described. The examples described below are illustrative and are intended to be only for the explanation of the present application and cannot be understood as a limitation of the present application. In the examples, the specific techniques or conditions not 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.

[0218] Example 1

[0219] (1) Preparation of positive electrode active material:

[0220] Step S1: Preparation of Fe-doped manganese oxalate

[0221] Put 807.1 g of manganese carbonate and 345.9 g of ferrous carbonate into a mixer and mix well for 6 hours. Then, transfer the obtained mixture into a reaction kettle, and add 5 L of deionized water and 1260.6 g of dihydrate oxalic acid, heat to 80°C, and mix well at a rotation speed of 500 rpm for 6 hours until the reaction is terminated and no bubbles are generated, to obtain manganese iron oxalate dihydrate (calculated as C2O4Mn 0.6 Fe 0.4 ·2H2O).

[0222] Step S2: Preparation of inner core LiMn 0.7 Fe 0.3 PO4

[0223] Take 1792.3 g of manganese iron oxalate dihydrate (calculated as C2O4Mn 0.6 Fe 0.4 ·2H2O) obtained in (1), 369.4 g of lithium carbonate, 1150.1 g of ammonium dihydrogen phosphate, and 4.9 g of dilute sulfuric acid, and add them into 20 L of deionized water, mix well, and react uniformly at 80°C for 10 hours to obtain a slurry. Transfer the slurry into a spray drying device to perform spray drying granulation, dry at a temperature of 250°C to obtain a powder. Sinter the powder in a roller kiln at 700°C for 4 hours in a protective atmosphere (90% nitrogen and 10% hydrogen) to obtain the above-mentioned inner core material.

[0224] Step S3: Carbon layer coating

[0225] Dissolve 67.2 g of sucrose in 500 g of deionized water, then stir and dissolve well to obtain a sucrose aqueous solution. Add 1633.9 g of the inner core material obtained in step S2 into the sucrose solution, and mix together for 6 hours. After uniform mixing, transfer into an oven at 150°C to dry for 6 hours, and then sinter at 700°C for 10 hours to obtain the material coated with a carbon layer, i.e., the positive electrode active material.

[0226] (2) Preparation of positive electrode sheet:

[0227] The positive electrode active material, the binder polyvinylidene fluoride (PVDF), and the conductive agent acetylene black are dissolved in the solvent N-methyl pyrrolidone (NMP) in a mass ratio of 97:2:1, and after being fully stirred and uniformly mixed, a positive electrode slurry is prepared; the positive electrode slurry is uniformly coated on the positive electrode current collector aluminum foil, and then after drying, cold pressing, and slitting, a positive electrode sheet is obtained, wherein the porosity is changed by adjusting the cold pressing operation parameters.

[0228] (3) Preparation of the negative electrode sheet: the negative electrode active material artificial graphite, the conductive agent acetylene black, the binder styrene-butadiene rubber (SBR), and the thickening agent sodium carboxymethyl cellulose (CMC-Na) are dissolved in deionized water in a mass ratio of 95:2:2:1, and after being fully stirred and uniformly mixed, a negative electrode slurry is prepared; the negative electrode slurry is coated on the negative electrode current collector copper foil, and then after drying, cold pressing, and slitting, a negative electrode sheet is obtained.

[0229] (4) Separating membrane: a polypropylene film is used.

[0230] (5) Preparation of the electrolyte: in an argon atmosphere glove box (H2O <0.1 ppm, O2 <0.1 ppm), ethylene carbonate (EC) and methyl ethyl carbonate (EMC) are mixed in a volume ratio of 3:7, then LiPF6 is uniformly dissolved in the above solution, and then electrolyte additive compound 1-1 is added and uniformly mixed to obtain an electrolyte. In the electrolyte, the concentration of LiPF6 is 1 mol / L, and the mass percentage of the electrolyte additive in the electrolyte is 2%.

[0231] (6) Preparation of the secondary battery: the above positive electrode sheet, the separating membrane, and the negative electrode sheet are stacked and wound in sequence to obtain an electrode assembly; the electrode assembly is placed in an outer package, the above prepared electrolyte is added, and after processes such as packaging, standing, formation, and aging, a secondary battery is obtained.

[0232] Example 2-68 and Comparative Example 1-3 are similar to the secondary battery preparation method of Example 1, but the parameters are adjusted, and the different parameters are shown in Table 2.

[0233] Table 2

[0234] Table 3: Parameter results of Examples 1-68 and Comparative Example 1-3

[0235] Material testing and battery testing

[0236] (1) Porosity test of the positive electrode film layer:

[0237] According to the national standard GB / T 24586-2009, the full-automatic true density tester (model AccuPyc II 1340) is used for testing in combination with the instrument instruction.

[0238] (2) Test of mass ratio of carbon coating layer in positive electrode active material:

[0239] According to the standard GB / T 20123-2006 / ISO 15350:2000JJG 395-1997, the carbon-sulfur analyzer is used to test the mass ratio of carbon element in the positive electrode active material, and the mass ratio of carbon coating layer in the positive electrode active material is obtained.

[0240] (3) Test of molar ratio of sp2 hybrid carbon atoms and sp3 hybrid carbon atoms in carbon coating layer:

[0241] XPS is used to determine the peak components of sp2 and sp3, and XPX-Peak software can be used to fit the peaks. Since the bond length of sp3 is longer than that of sp2, the binding energy of sp3 is 285.2±0.1eV, and the binding energy of sp2 is 284.4±0.1eV. According to the Lorentz-Gaussian function fitting the area occupied by sp2 and sp3 hybrid carbon, the molar ratio of sp2 hybrid carbon and sp3 hybrid carbon can be quantitatively calculated according to the proportion of sp2 area to the total area of sp3 peak.

[0242] (4) Test of BET specific surface area of positive electrode active material:

[0243] According to the national standard GB / T 19587-2004, 8-15g of the sample to be tested is loaded into the sample tube, and the initial mass of the sample to be tested is recorded. The weighed sample to be tested is loaded into the specific surface and pore size tester (American Conta NOVA2000e type). Then start degassing, and heat the sample to be tested to 200℃ and keep for 2h. Then record the mass of the sample to be tested after degassing. Then the degassed sample to be tested is reloaded into the specific surface and pore size tester, and liquid nitrogen is poured into the BET test. After the test is completed, the BET specific surface area is read from the test results.

[0244] (5) Test of powder resistivity of positive electrode active material:

[0245] The powder resistivity is tested using the Yuan Energy Technology PRCD1000 device. Turn on the power and test software of the device, use the balance to weigh the positive electrode active material powder, use the mold to press the powder into a thin sheet, place the thin sheet into the device, configure the test pressure to 5t, the pressure holding time to 5s, click test, and the powder resistivity of the positive electrode active material is displayed after the test is completed.

[0246] (6) Test of 45℃ cycle performance of lithium ion battery:

[0247] The battery was charged at 1C constant current to 4.2V at 45℃, then charged at 4.2V constant voltage to current≤0.05C, and then discharged at 1C constant current to 2.5V, which was one charge-discharge cycle. The discharge capacity at this time was recorded as the discharge capacity of the first cycle of the battery. The charging and discharging cycles were repeated, and the cycle number corresponding to the capacity retention rate of 80% was calculated.

[0248] Capacity retention rate (%) = (discharge capacity of the Nth cycle of the battery / discharge capacity of the first cycle of the battery) x 100%.

[0249] (7) 60℃ storage performance test of lithium ion battery

[0250] The battery was charged at 0.33C to 3.65V and then discharged at 0.33C to 2.5V at 25℃ constant temperature environment to test the discharge capacity D1. The battery was stored in a constant temperature environment at 60℃, and was taken out every 30 days for testing. Before each test, the battery was cooled to 25℃, and then charged at 0.33C to 3.65V and discharged at 0.33C to 2.5V to test the discharge capacity. Until the storage time was equal to 90 days, the capacity retention rate at this time was recorded.

[0251] Capacity retention rate (%) = (discharge capacity after 90 days of storage / discharge capacity of the first storage of the battery) x 100%.

[0252] Table 4: Performance test results of examples 1-68 and comparative examples 1-3

[0253] According to the above results, it can be seen that:

[0254] Compared with the positive electrode film layer porosity of 8% in comparative example 1, the cycle life and storage performance of the batteries of examples 1-57, 62-68 are significantly improved, and the cycle life of the battery of example 58 is significantly improved.

[0255] Compared with the positive electrode film layer porosity of 40% in comparative example 2, the cycle life and storage performance of the batteries of examples 1-57, 62, 64-68 are significantly improved, and the storage performance of the battery of example 63 is improved.

[0256] Compared with the electrolyte additive not used in comparative example 3, the cycle life and storage performance of the batteries of examples 1-58, 62-68 are significantly improved.

[0257] Compared with the high mass ratio of the electrolyte additive of Example 62 in the electrolyte, the cycle life and storage performance of the batteries of Examples 6, 46-50 are improved; compared with the low mass ratio of the electrolyte additive of Example 63 in the electrolyte, the cycle life and storage performance of the batteries of Examples 6, 46-50 are improved.

[0258] Compared with the low porosity of the positive electrode film layer of Example 64, the cycle life and storage performance of the batteries of Examples 6, 51-52 are improved; compared with the high porosity of the positive electrode film layer of Example 65, the cycle life and storage performance of the batteries of Examples 6, 51-52 are improved.

[0259] Compared with the small molar ratio of sp2 hybrid carbon atoms to sp3 hybrid carbon atoms in the carbon coating layer of Example 66, the cycle life and storage performance of the batteries of Examples 6, 55 are improved.

[0260] Compared with the high ratio of the carbon coating layer in the positive electrode active material of Example 67 and the small BET of the positive electrode active material, the cycle life and storage performance of the batteries of Examples 6, 53-54, 56-57 are improved; compared with the low ratio of the carbon coating layer in the positive electrode active material of Example 68 and the large BET of the positive electrode active material, the cycle life and storage performance of the batteries of Examples 6, 53-54, 56-57 are improved.

[0261] Compared with the absence of the carbon coating layer of Example 58, the cycle life and storage performance of the batteries of Examples 6, 53-54, 56-57, 67-68 are higher.

[0262] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are only examples, and embodiments having the same technical idea and playing the same role and effect within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the components of the embodiments are also included in the scope of the present application.

Claims

1. A secondary battery, comprising a positive electrode sheet and a non-aqueous electrolyte, the positive electrode sheet comprising a positive electrode current collector and a positive electrode film layer on at least one side surface of the positive electrode current collector, the positive electrode film layer having a porosity of 10%-35%, and the non-aqueous electrolyte comprising an electrolyte additive; the electrolyte additive comprising one or more of a substituted or unsubstituted 5-12-membered aromatic heterocyclic organic base additive, a substituted or unsubstituted 5-12-membered aliphatic heterocyclic organic base additive.

2. The secondary battery according to claim 1, wherein The electrolyte additive includes one or more of a compound represented by structural formula (I), a compound represented by structural formula (II), a compound represented by structural formula (III), a compound represented by structural formula (IV), and a compound represented by structural formula (V): wherein, in the structural formula (I), Y1and Y2are each independently selected from a C atom and a N atom, R1, R2, R3, R4and R5are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 24 OH, -R 25 NR 26 R 27 , wherein R 24 and R 25 are each independently selected from a C0-C6alkylene group, a C2-C6alkenylene group, R 26 and R 27 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group, or R 26 , R 27 and the N atom form a 5-8 membered aliphatic heterocyclic ring containing 2-4 heteroatoms, the heteroatoms including the N atom, the S atom, the P atom; or R2and / or R4are absent; In structural formula (II), W1 is selected from a C atom, a N atom, an O atom and a S atom, W2 is selected from a C atom and a N atom, R6, R7, R8 and R9 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C3-C8 cycloalkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, -R 28 OH, -R 29 NR 30 R 31 ; wherein R 28 and R 29 are each independently selected from a C0-C6 alkylene group, R 30 and R 31 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a halogenated C1-C6 alkyl group; In structural formula (III), A1, A2, A3, A4and A5are each independently selected from a C atom and a N atom, R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -R 32 OH, -R 33 NR 34 R 35 ; wherein R 32 and R 33 are each independently selected from a C0-C6alkylene group, R 34 and R 35 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group; or one or more of R 10 , R 10’ , R 11 and R 14 is absent; In structural formula (IV), X1, X2, X3and X4are each independently selected from a C atom and an N atom, a and b are each independently selected from an integer from 0 to 3, R 16 , R 17 and R 18 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a C1-C6alkoxy group, a C2-C6alkenyl group, a C2-C6alkynyl group, -OH, -NR 36 R 37 ; wherein R 36 and R 37 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6alkyl group, a halogenated C1-C6alkyl group; or R 18 is absent. In structural formula (V), V1, V2, V3 and V4 are each independently selected from a C atom and an N atom, d is selected from an integer of 0-3, R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a C1-C6 alkoxy group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, -OH, -NR 38 R 39 ; wherein R 38 and R 39 are each independently selected from a hydrogen atom, a halogen atom, a C1-C6 alkyl group, a halogenated C1-C6 alkyl group.

3. The secondary battery according to claim 1 or 2, wherein The positive electrode film layer has a porosity of 18%-27%.

4. The secondary battery according to any one of claims 1 to 3, wherein The positive electrode film layer comprises a positive electrode active material, and the positive electrode active material comprises an inner core and a carbon coating layer covering the inner core.

5. The secondary battery according to claim 4, wherein The carbon coating layer comprises sp2 hybridized carbon atoms.

6. The secondary battery according to claim 5, wherein The carbon coating layer further comprises sp3 hybridized carbon atoms; and the molar ratio of the sp2 hybridized carbon atoms to the sp3 hybridized carbon atoms is ≥0.3, ≥0.5, or 0.5-10.

7. The secondary battery according to any one of claims 4 to 6, wherein The mass percentage of the carbon coating layer in the positive electrode active material is 0.8%-3.5% or 1.3%-2.5%.

8. The secondary battery according to any one of claims 1 to 7, wherein The positive electrode film layer includes a positive electrode active material, the BET specific surface area of the positive electrode active material is 8-30 m 2 / g or 10-25 m 2 / g.

9. The secondary battery according to any one of claims 1 to 8, wherein The positive electrode film layer comprises a positive electrode active material, and the positive electrode active material has a powder resistivity of 10-200Ω·cm or 10-100Ω·cm.

10. The secondary battery according to any one of claims 4 to 7, wherein The inner core comprises one or more of lithium manganese iron phosphate, lithium iron phosphate, lithium manganese phosphate, lithium vanadium phosphate, lithium vanadium iron phosphate, lithium vanadium manganese phosphate, and lithium manganese vanadium phosphate.

11. The secondary battery according to any one of claims 1 to 10, wherein The mass percentage of the electrolyte additive in the non-aqueous electrolyte is 0.05%-20% or 0.1%-10%.

12. The secondary battery according to any one of claims 1 to 11, wherein In the structural formula (Ⅰ), R1, R2, R3, R4and R5are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -R 24 OH, -R 25 NR 26 R 27 ; wherein R 24 and R 25 are each independently selected from the group consisting of C0-C4alkylene, R 26 and R 27 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group, or R 26 , R 27 and the N atom form a 5-6 membered aliphatic heterocycle containing 2 heteroatoms, which are N atoms; or, R2and / or R4are absent; or, R1, R2, R3, R4 and R5 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, a hydroxyl C1-C4 alkyl group, -NH2, a di C1-C4 alkyl amine group, an amino C1-C4 alkyl group, and piperazinyl; or, R2 and / or R4 are absent; or, R1, R2, R3, R4and R5are each independently selected from the group consisting of a hydrogen atom, a F atom, a Cl atom, a Br atom, a methyl group, an ethyl group, a n-propyl group, an i-propyl group, a t-butyl group, a methoxy group, an ethoxy group, an allyl group, an propargyl group, -OH, a hydroxymethyl group, a hydroxyethyl group, -NH2, -N(CH3)2, -CH2NH2, or, R2 and / or R4 are absent; or, R1, R2, R3, R4and R5are each independently selected from the group consisting of a hydrogen atom, a F atom, a methyl group, a tert-butyl group, a methoxy group, a hydroxymethyl group, -N(CH3)2, -CH2NH2, or, R2 and / or R4 are absent.

13. The secondary battery according to any one of claims 1 to 12, wherein In the structural formula (Ⅱ), R6, R7, R8and R9are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C3-C5cycloalkyl group, a C2-C4alkenyl group, a C2-C4alkynyl group, -R 28 OH, -R 29 NR 30 R 31 ; wherein R 28 and R 29 are each independently selected from the group consisting of C0-C4alkylene, R 30 and R 31 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group; or, R6, R7, R8 and R9 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, a C3-C5 cycloalkyl group, a C2-C4 alkenyl group, a C2-C4 alkynyl group, -OH, a hydroxyl C1-C4 alkyl group, -NH2, a mono C1-C4 alkyl amine group, a di C1-C4 alkyl amine group, and an amino C1-C4 alkyl group; or, R6, R7, R8 and R9 are each independently selected from a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, a n-propyl group, an iso-propyl group, a methoxy group, an ethoxy group, a cyclopropyl group, a cyclobutyl group, an allyl group, an propargyl group, -OH, a hydroxyl methyl group, a hydroxyl ethyl group, -NH2, -NHCH3, -N(CH3)2, and -CH2NH2; or, R6, R7, R8 and R9 are each independently selected from a hydrogen atom, a fluorine atom, a methyl group, a cyclopropyl group, an allyl group, a hydroxyl methyl group, and -NHCH3.

14. The secondary battery according to any one of claims 1 to 13, wherein In the structural formula (Ⅲ), R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -R 32 OH, -R 33 NR 34 R 35 ; wherein R 32 and R 33 are each independently selected from the group consisting of C0-C4alkylene, R 34 and R 35 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or, R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, a hydroxy C1-C4alkyl group, -NH2, a mono C1-C4alkylamino group, a di C1-C4alkylamino group, an amino C1-C4alkyl group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or, R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, a methoxy group, an allyl group, an propargyl group, -OH, -NH2, -CH2NH2, -N(CH3)2; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent; or, R 10 , R 10’ , R 11 , R 12 , R 13 , R 14 and R 15 are each independently selected from a hydrogen atom, a methyl group, a methoxy group; or, one or more of R 10 , R 10’ , R 11 and R 14 is absent.

15. The secondary battery according to any one of claims 1 to 14, wherein In the structural formula (Ⅳ), R 16 , R 17 , and R 18 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, -NR 36 R 37 ; wherein R 36 and R 37 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4 alkyl group, a halogenated C1-C4 alkyl group; or, R 18 is absent; or, R 16 R 17 and R 18 Each is independently selected from hydrogen atom, halogen atom, C1-C4 alkyl, C1-C4 alkoxy, C2-C4 alkenyl, C2-C4 alkynyl, -OH, -NH2, -C1-C4 alkylamino, diC1-C4 alkylamino; or, R 18 Does not exist; or, R 16 , R 17 , and R 18 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a methoxy group, an ethoxy group, an allyl group, an propargyl group, -OH, -NH2, -NHCH3, -N(CH3)2; or, R 18 is absent; or, R 16 , R 17 , and R 18 are each independently selected from a hydrogen atom, a methyl group, -N(CH3)2; or, R 18 is absent.

16. The secondary battery according to any one of claims 1 to 15, wherein In the structural formula (Ⅴ), R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from the group consisting of a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, -NR 38 R 39 ; wherein R 38 and R 39 each independently is selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a halogenated C1-C4alkyl group; or, R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from a hydrogen atom, a halogen atom, a C1-C4alkyl group, a C1-C4alkoxy group, a C2-C4alkenyl group, a C2-C4alkynyl group, -OH, -NH2, a mono C1-C4alkylamino group, a di C1-C4alkylamino group; or, R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from the group consisting of a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, a methyl group, an ethyl group, an n-propyl group, an i-propyl group, a t-butyl group, a methoxy group, an ethoxy group, an allyl group, an propargyl group, -OH, -NH2, -NHCH3, -N(CH3)2; or, R 19 , R 20 , R 21 , R 22 and R 23 are each independently selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, an isopropyl group, a tert-butyl group.

17. The secondary battery according to any one of claims 1 to 16, wherein, in the structural formula (I), 0, 1 or 2 of Y1and Y2are N atoms; and / or, in the structural formula (II), at least one of W1and W2is a N atom; and / or, in the structural formula (III), at least one of A1, A2, A3, A4and A5is a N atom; and / or, in the structural formula (IV), at least one of X1, X2, X3and X4is a N atom; and / or, in the structural formula (V), at least one of V1, V2, V3and V4is a N atom.

18. The secondary battery according to any one of claims 1 to 17, wherein, in the structural formula (I), 0, 1 or 2 of Y1and Y2are N atoms; and / or, in the structural formula (II), at least one of W1and W2is a N atom; and / or, in the structural formula (III), 1, 2, 3 or 4 of A1, A2, A3, A4and A5are N atoms; and / or, in the structural formula (IV), 2 or 3 of X1, X2, X3and X4are N atoms; and / or, in the structural formula (V), 1, 2 or 3 of V1, V2, V3and V4are N atoms.

19. The secondary battery according to any one of claims 1 to 18, wherein The compound of structural formula (I) is selected from at least one of the following compounds:

20. The secondary battery according to any one of claims 1 to 18, wherein The compound of structural formula (II) is selected from at least one of the following compounds:

21. The secondary battery according to any one of claims 1 to 18, wherein The compound of structural formula (III) is selected from at least one of the following compounds:

22. The secondary battery according to any one of claims 1 to 18, wherein The compound of structural formula (IV) is selected from at least one of the following compounds:

23. The secondary battery according to any one of claims 1 to 18, wherein The compound of structural formula (V) is selected from at least one of the following compounds:

24. An electric device comprising the secondary battery according to any one of claims 1 to 23.

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