Battery

Abstract

A battery, comprising a positive electrode and an electrolyte. The electrolyte comprises a fluoronitrile solvent, and the fluoronitrile solvent is a fluoronitrile compound. The positive electrode comprises a positive electrode active material, and the positive electrode active material comprises lithium cobalt oxide and a nickel-cobalt-manganese ternary material. Based on the total mass of the positive electrode active material, the mass content of the nickel element is k wt%, wherein 0 wt%<k wt%≤24 wt%. The battery can significantly mitigate the problem of lithium precipitation of battery cells, has high cycle stability and high overcharge-resistant performance, and can significantly reduce cost.

Description

A battery TECHNICAL FIELD

[0001] The present disclosure relates to the field of energy storage technology, and in particular to a battery.

[0002] BACKGROUND

[0003] In recent years, the competition of lithium ion batteries has entered a white-hot stage. Head enterprises will gradually expand market share by virtue of technology, quality, scale and environmental governance advantages, and the industry concentration will further improve. Among them, the cost reduction and efficiency improvement of lithium ion battery products are the core driving force for long-term development. Therefore, lithium ion batteries need to be designed innovatively in system, iteratively updated in materials, and continuously optimized in cost performance, so as to meet the requirements of high energy density and high cost performance of lithium ion batteries. However, after the above optimization design of lithium ion battery products, the safety problems such as lithium precipitation and overcharge caused by high voltage and fast charging are still widespread, which seriously affects the development of the lithium ion battery industry. SUMMARY

[0004] The present disclosure provides a battery comprising a positive electrode and an electrolyte. The battery of the present disclosure can significantly improve the problem of lithium precipitation of the battery cell; the battery of the present disclosure has high cycle stability and high overcharge resistance; the battery of the present disclosure can significantly reduce the cost.

[0005] To achieve the above-mentioned purpose, the technical solution adopted by the present disclosure is as follows:

[0006] The present disclosure provides a battery, the battery comprising a positive electrode and an electrolyte,

[0007] The electrolyte comprises a fluoronitrile solvent; the fluoronitrile solvent is a fluoronitrile compound.

[0008] The positive electrode comprises a positive electrode active material, the positive electrode active material comprising lithium cobaltate and a nickel-cobalt-manganese ternary material, wherein the mass content of nickel element is k wt%, 0 wt% < k wt% ≤ 24 wt% based on the total mass of the positive electrode active material.

[0009] Through the above technical solution, the present disclosure has at least the following advantages compared with the prior art:

[0010] The fluoronitrile solvent in the electrolyte of the present disclosure is a fluoronitrile compound, which can not only make lithium ions in the electrolyte smoothly deintercalate under high voltage and large current conditions, but also complex with metal ions of the positive electrode active material to reduce the dissolution of metal ions under high voltage conditions. The compound can protect the stability of the positive electrode structure and reduce the occurrence of negative electrode side reactions, significantly improving the problem of lithium precipitation of the battery cell. Moreover, the compound has strong oxidation resistance and high voltage resistance, enabling the lithium ion battery to simultaneously achieve high cycle performance and excellent overcharge resistance. Further, by reasonably adjusting the content k wt% of nickel element in the positive electrode active material, the present disclosure can further improve the complex reaction degree of the electrochemically active sites formed by the carbon-nitrogen triple bond in the fluoronitrile compound and the metal ions on the surface of the positive electrode active material, so that the combination of metal ions and fluoronitrile compounds is more closely, thereby reducing the dissolution of metal ions, and enabling the positive electrode active material mixed with nickel-cobalt-manganese ternary material to be effectively protected by the fluoronitrile solvent, further improving the cycle performance and overcharge resistance of the battery. In addition, the positive electrode active material of the present disclosure adopts the mixed form of lithium cobaltate and nickel-cobalt-manganese ternary material, which can enable the battery to have high energy density and high cost performance, thereby significantly reducing the cost of the battery.

[0011] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint. Any ranges of values disclosed herein are not to be limited to the precise values stated as that endpoint. Any endpoints of ranges of values in the context of ranges of values are not to be construed as specifically limiting the ranges of values to the recited endpoint value. Ranges of values can be combined to form new ranges of values, whether explicitly described or not, and any value within those ranges is contemplated. DETAILED DESCRIPTION

[0012] The specific embodiments of the present disclosure are described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and explanatory and are not intended to limit the disclosure.

[0013] In the detailed description and in the claims, a list of items joined by the term "at least one of" or "one or more of" can mean any combination of the items in the list. For example, if the items in a list are A, B, and C, the phrase "at least one of A, B, and C" can mean A alone; B alone; C alone; A and B together; A and C together; B and C together; or A, B, and C together. The item A can include an individual element or multiple elements. The item B can include an individual element or multiple elements. The item C can include an individual element or multiple elements.

[0014] Lithium cobalt oxide, commonly used in positive electrode active materials, has a theoretical specific capacity of approximately 274 mAh / g and an actual compacted density of 3.6–4.2 g / cm³. 3 It possesses extremely high volumetric energy density, and the Co-O bond force is stronger than the Li-O bond, which facilitates the Li-O bond interaction during charging and discharging. + The layered structure of lithium cobalt oxide is not easily collapsed due to the extraction and insertion of CoO2 between layers, thus ensuring good cycle stability and safety. However, because cobalt is an expensive metal, the preparation cost of lithium cobalt oxide cathode materials is relatively high, limiting its widespread application. Nickel-cobalt-manganese ternary materials, on the other hand, are cathode active materials with a theoretical specific capacity comparable to lithium cobalt oxide, but their preparation cost is significantly lower. Therefore, by doping the cathode active material with nickel-cobalt-manganese ternary materials, the cost of the cathode material can be effectively reduced. Moreover, the actual compaction density of nickel-cobalt-manganese ternary materials is 3.4–3.8 g / cm³. 3 Slightly lower than lithium cobalt oxide, by adopting a combination design of lithium cobalt oxide and nickel-cobalt-manganese ternary materials, the positive electrode active material can simultaneously have high energy density and high cost performance, thereby reducing costs. However, the positive electrode protection additives commonly used in electrolytes have a much lower binding capacity with nickel-cobalt-manganese ternary materials than with lithium cobalt oxide. Therefore, during cycling, nickel and manganese ions in the positive electrode active material cannot be well protected, causing transition metal ions to dissolve to the negative electrode surface and react, damaging the negative electrode interface film, leading to an aggravation of side reactions in the electrolyte, resulting in a continuous deterioration of the battery's cycle performance. Moreover, safety issues such as lithium plating and overcharging caused by high voltage and fast charging are still common.

[0015] In view of the problems existing in the prior art, this disclosure provides a battery, the battery comprising a positive electrode and an electrolyte.

[0016] The electrolyte includes a fluoronitrile solvent; the fluoronitrile solvent is a fluoronitrile compound.

[0017] The positive electrode includes a positive electrode active material, which includes lithium cobalt oxide and nickel-cobalt-manganese ternary materials. The nickel content is k wt%, with 0 wt% < k wt% ≤ 24 wt%, based on the total mass of the positive electrode active material.

[0018] The electrolyte provided by the present disclosure comprises a fluoronitrile solvent, which is a fluoronitrile compound having a high-energy carbon-nitrogen triple bond in the structure of the compound, and the introduction of fluorine atoms further enhances the electron attraction of the nitrogen atom on the cyano group, making the carbon-nitrogen bond more firm and enhancing the polarity of the carbon-nitrogen triple bond. It can not only form a high-speed lithium ion solvation sheath with lithium ions, allowing lithium ions to smoothly deintercalate under high voltage and large current conditions, but also enhance the degree of complexation reaction of the carbon-nitrogen triple bond with the electrochemically active sites formed by the metal ions on the surface of the positive active material, reduce the side reactions of the electrolyte with the active sites, and reduce the dissolution of nickel ions and manganese ions in the positive active material under high voltage conditions, thereby protecting the stability of the positive electrode structure and avoiding the destruction of the negative electrode interface film, thereby significantly improving the lithium precipitation problem of the battery, allowing the battery provided by the present disclosure to achieve high cycle performance. Moreover, due to the high-energy carbon-nitrogen triple bond in the structure of the compound, the oxidation resistance and high-voltage resistance of the compound are particularly strong, which can improve the voltage window of the electrolyte. The electrolyte using the fluoronitrile compound has a wide temperature range, high dielectric constant, and high conductivity, and can better dissolve lithium salt and additives, so that the electrolyte has high stability, and the high-voltage resistance and high-temperature resistance of the battery are effectively improved, thereby allowing the lithium ion battery to simultaneously achieve high cycle performance and excellent overcharge resistance.

[0019] Further, since the nickel element on the surface of the positive active material has a stronger binding ability with the fluoronitrile compound than the manganese element, by reasonably adjusting the content k wt% of the nickel element in the positive active material, the complexation reaction degree of the electrochemically active sites formed by the carbon-nitrogen triple bond in the fluoronitrile compound and the metal ions on the surface of the positive active material can be further improved, so that the metal ions and the fluoronitrile compound are more tightly combined, and the dissolution of the metal ions is reduced, thereby allowing the positive active material doped with nickel-cobalt-manganese ternary material to be effectively protected by the fluoronitrile solvent, and further improving the cycle performance and overcharge resistance of the battery.

[0020] In addition, by using lithium cobaltate and nickel-cobalt-manganese ternary material doped with each other, the battery can have high energy density and high cost performance, thereby significantly reducing the cost of the battery.

[0021] In an embodiment, the mass content of nickel element in the positive electrode active material is k wt%, 0 wt% < k wt% ≤ 24 wt%, based on the total mass of the positive electrode active material. In an embodiment, k wt% can be 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, or a range consisting of any two of these values. When the mass content of nickel element k wt% is equal to 0, it means that the positive electrode active material is substantially all lithium cobaltate, without blending ternary material, so that although the material has high compaction density and high volumetric energy density, its thermal stability is poor, the overcharge resistance under high voltage and large current conditions is poor, and the preparation cost is high; when the mass content of nickel element k wt% is greater than 24 wt%, it means that the content of nickel element in the nickel-cobalt-manganese ternary material is too high, which can cause part of the nickel ions not complexed by fluoronitrile compounds to dissolve to the negative electrode surface and react, destroy the interface film of the negative electrode, cause the stability of the positive electrode active material to decrease, and further cause the capacity loss of the battery during cyclic charging and discharging and the capacity accelerated decay in a high temperature environment, affecting the capacity retention rate of the battery, and also causing the degradation of lithium precipitation problem of the battery cell, therefore, it is necessary to control the content of nickel element k wt% in the positive electrode active material within a suitable range. In a preferred embodiment, 0 wt% < k wt% ≤ 15 wt%. In the present disclosure, the mass content of nickel element in the positive electrode active material can be obtained by inductively coupled plasma emission spectrometer (ICP) test; it should be noted that the positive electrode includes a positive electrode current collector and a positive electrode active material layer on at least one side surface of the positive electrode current collector, the positive electrode active material is contained in the positive electrode active material layer, and the positive electrode active material layer can further include a conductive agent and a binder.

[0022] In the present disclosure, the positive electrode active material is mixed with lithium cobaltate and nickel-cobalt-manganese ternary material. In addition to reducing the cost of the material, the cobalt element in the nickel-cobalt-manganese ternary material can also prevent Li-Ni mixing and improve the order of lithium ion deintercalation. The manganese element can maintain the stability of the positive electrode active material structure, and the nickel element is the main force for the positive electrode active material to achieve high capacity. However, the content of the above-mentioned transition metal elements should not be too much. Excessive cobalt element will greatly increase the cost of the material and cause the capacity to decrease. Excessive manganese element and nickel element are easy to dissolve into the negative electrode and react. Therefore, by further adjusting the mass ratio of each element in the positive electrode active material, the reversible specific capacity and cycle stability of the battery can be significantly improved, and the cost can be significantly reduced. In a specific embodiment, the mass ratio of each element in the positive electrode active material is Ni:Co:Mn=(2-24):(0.5-8):(0.6-9). In a specific embodiment, Ni:Co:Mn can be 2:0.5:0.6, 2:0.5:9, 2:8:0.6, 2:8:9, 24:0.5:0.6, 24:0.5:9, 24:8:0.6, 24:8:9, 12:4.2:5, 4:1.2:1.13, 4:1.2:3.37, 4:3.6:1.13, 4:3.6:3.37, 10:1.2:1.13, 10:1.2:3.37, 10:3.6:1.13, 10:3.6:3.37. In addition, the 2-24 can be 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22 or 24, the 0.5-8 can be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or 8, and the 0.6-9 can be 0.6, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5 or 9.

[0023] In a preferred embodiment, Ni:Co:Mn=(4-10):(1.2-3.6):(1.13-3.37). The mass ratio of each element in the positive electrode active material can also be tested by inductively coupled plasma emission spectrometer (ICP).

[0024] In addition, in order to further improve the complexing reaction degree and binding capacity of fluoronitrile compounds with metal ions in the nickel-cobalt-manganese ternary material in the electrolyte, and solve the problem that fluoronitrile compounds cannot efficiently bind with manganese ions on the surface of the positive active material, the average particle size of the primary particles (single crystals or polycrystals) of the nickel-cobalt-manganese ternary material can be controlled within a certain range; because the specific surface area of small particles of the nickel-cobalt-manganese ternary material is larger, the contact area between the ternary material and the fluoronitrile compound is increased, effectively improving the complexing reaction degree of the fluoronitrile compound with manganese ions, thereby strengthening the protection of the fluoronitrile solvent on the transition metal ions on the surface of the positive electrode, and further reducing the dissolution of manganese ions. In a specific embodiment, the average particle size Dv50 of the primary particles of the nickel-cobalt-manganese ternary material is 0.1 μm to 6 μm. In a specific embodiment, the average particle size of the primary particles of the nickel-cobalt-manganese ternary material can be 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, 2 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, 3.1 μm, 3.3 μm, 3.5 μm, 3.7 μm, 3.9 μm, 4 μm, 4.2 μm, 4.4 μm, 4.6 μm, 4.8 μm, 5 μm, 5.1 μm, 5.3 μm, 5.5 μm, 5.7 μm, 5.9 μm, 6 μm, or a range consisting of any two of these values. In a preferred embodiment, the average particle size Dv50 of the primary particles of the nickel-cobalt-manganese ternary material is 0.12 μm to 3 μm. In the present disclosure, the average particle size Dv50 of the primary particles of the nickel-cobalt-manganese ternary material can be obtained by observing the size of the particles by scanning electron microscopy (SEM).

[0025] In the present disclosure, the mass content of the fluoronitrile solvent is c wt% based on the total mass of the electrolyte, 3 wt%≤ c wt%≤ 40 wt%. In a specific embodiment, c wt% can be 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15 wt%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25 wt%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35 wt%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, or a range consisting of any two of these values. When the mass content of the fluoronitrile solvent c wt% is less than 3 wt%, it means that the content of the fluoronitrile solvent in the electrolyte is too low, and after part of the fluoronitrile solvent in the electrolyte participates in the complexation of transition metal ions on the surface of the positive electrode, it is impossible to achieve efficient transport of a large number of lithium ions under fast charging conditions, resulting in the accumulation of lithium ions on the surface of the negative electrode, the destruction of the SEI film of the negative electrode, the increase of the risk of internal short circuit of the battery, the decrease of the safety of the battery, and the acceleration of the electrode loss and the decrease of the capacity retention rate of the battery. When the mass content of the fluoronitrile solvent c wt% is greater than 40 wt%, the content of the fluoronitrile solvent is too high, the viscosity of the electrolyte increases, the flowability becomes poor, which is not conducive to the transport of lithium ions, and the problem of lithium precipitation is prone to occur during the deintercalation process. Therefore, by adjusting the mass content of the fluoronitrile solvent c within a specific range, the occurrence of lithium precipitation can be further avoided, and the demand for high safety (such as oven temperature and overcharge) and high cycle capacity retention rate of lithium ion batteries under high voltage or fast charging conditions can be met. Moreover, by further adjusting the mass content of the fluoronitrile solvent c wt%, the concentration of the carbon-nitrogen triple bond in the fluoronitrile compound can be adjusted to an appropriate level, the complexation reaction effect with metal ions of the electrochemically active site can be further improved, the combination of metal ions and fluoronitrile compounds can be more closely, the dissolution of metal ions can be further reduced, and the cycle performance and overcharge resistance of lithium ion batteries using nickel-cobalt-manganese ternary material mixed positive electrodes can be improved. In a preferred embodiment, 4 wt%≤ c wt%≤ 30 wt%, and it can be further preferred that 4 wt%≤ c wt%≤ 20 wt%.

[0026] In addition to the fluoronitrile solvent, the electrolyte of the present disclosure can also include other basic electrolyte solvents such as ethylene carbonate, propylene carbonate, and carboxylic acid ester solvents.

[0027] In an embodiment, the mass content of the ethylene carbonate (EC) is w1 wt%, w1 wt%≤20wt% based on the total mass of the electrolyte. In an embodiment, the mass content of the ethylene carbonate w1 wt% can be 20wt%, 19wt%, 18wt%, 17wt%, 16wt%, 15wt%, 14wt%, 13wt%, 12wt%, 11wt%, 10wt%, 9wt%, 8wt%, 7wt%, 6wt%, 5wt%, 4wt%, 3wt%, 2wt%, 1wt%, 0wt% or a range consisting of any two of these values. Ethylene carbonate with high dielectric constant and LiPF6 exist solvation-desolvation process, which can form a uniform and dense SEI film rich in organic-inorganic at the first charge-discharge, but too dense SEI film usually has slightly larger impedance, which is not conducive to large current fast charging. Therefore, the amount of ethylene carbonate should not be too much, so the mass content of ethylene carbonate needs to be controlled within a suitable range. In a preferred embodiment, 0wt%≤w1 wt%≤15wt%;

[0028] In an embodiment, the mass content of the propylene carbonate (PC) is w2 wt%, w2 wt%≤20wt% based on the total mass of the electrolyte. In an embodiment, the mass content of the propylene carbonate w2 wt% can be 20wt%, 19wt%, 18wt%, 17wt%, 16wt%, 15wt%, 14wt%, 13wt%, 12wt%, 11wt%, 10wt%, 9wt%, 8wt%, 7wt%, 6wt%, 5wt%, 4wt%, 3wt%, 2wt%, 1wt%, 0wt% or a range consisting of any two of these values. Propylene carbonate does not exist solvation with lithium ions, but its high dielectric constant is usually used with ethylene carbonate, which can significantly enhance the conductivity of the electrolyte and is conducive to large rate charge-discharge. However, the mass content of propylene carbonate should not be too much, which will cause its continuous reduction decomposition at the first lithium intercalation potential (~0.7V), eventually causing the structure collapse of carbon materials (such as graphite) in the negative electrode, which cannot normally intercalate and deintercalate lithium, thereby leading to the decrease of battery energy density and affecting the overall performance of the battery. Therefore, the mass content of propylene carbonate also needs to be controlled within a suitable range. In a preferred embodiment, 0wt%≤w2 wt%≤15wt%;

[0029] In an embodiment, the mass content of the carboxylic acid ester solvent is w3 wt%, w3 wt%≤70 wt% based on the total mass of the electrolyte. In an embodiment, the mass content of the carboxylic acid ester solvent w3 wt% can be 60 wt%, 55 wt%, 50 wt%, 45 wt%, 40 wt%, 35 wt%, 30 wt%, 25 wt%, 20 wt%, 19 wt%, 18 wt%, 17 wt%, 16 wt%, 15 wt%, 14 wt%, 13 wt%, 12 wt%, 11 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0 wt%, or a range between any two of these values. As an excellent solvent, the carboxylic acid ester solvent can dissolve lithium salts and various additives at room temperature and does not precipitate at low temperatures. In a preferred embodiment, 20 wt%≤w3 wt%≤60 wt%. In an embodiment, the carboxylic acid ester solvent includes at least one of propyl propionate (PP), ethyl propionate (EP), ethyl acetate (EA), or ethyl butyrate (EB).

[0030] Further, as previously described, appropriately increasing the amount of fluoronitrile solvent in the electrolyte can enhance the complexation reaction between the carbon-nitrogen triple bond in the fluoronitrile compound and the metal ion of the electrochemically active site, but too much fluoronitrile solvent can increase the viscosity and reduce the flowability of the electrolyte. In particular, free fluoride ions in the fluoronitrile solvent can easily combine with protons in the electrolyte to form Lewis acids that can easily destroy the active material on the positive electrode surface. Therefore, in order to maintain the flowability of the electrolyte and at the same time ensure protection of the transition metal on the positive electrode surface, in an embodiment, the mass content of the fluoronitrile solvent c wt%, the mass content of the nickel element k wt%, and the mass content of the carboxylic acid ester solvent w3 wt% satisfy the relationship: 56≤0.1k+0.7c+w3≤70. For example, 0.1k+0.7c+w3 can be 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, or a range between any two of these values. The mass content of the carboxylic acid ester solvent refers to the total mass content of all carboxylic acid ester solvents in the electrolyte, such as when the carboxylic acid ester solvent includes propyl propionate and ethyl acetate, the mass content of the carboxylic acid ester solvent is the sum of the mass content of propyl propionate and the mass content of ethyl acetate. By satisfying the above relationship, the metal ion in the active material on the positive electrode surface can be effectively protected by the fluoronitrile solvent, and the fluoronitrile solvent and the carboxylic acid ester solvent can work together to enhance the flowability of the electrolyte, which helps the lithium ion fluoronitrile solvent transport lithium ions, further improving the cycle performance of the battery. In a preferred embodiment, 58≤0.1k+0.7c+w3≤68.

[0031] In a specific embodiment, the fluoronitrile compound includes a fluoromononitrile compound, the fluoromononitrile compound includes at least one of the following compounds:

[0032] The fluoronitrile compound can also form an SEI film after experiencing solvation and desolvation with lithium ions extracted from the positive electrode due to its specific structure. Moreover, because the molecular weight of the fluoromononitrile compound is low, it can transport lithium ions faster and more efficiently, and the degree of solvation with lithium ions is lighter, which is more conducive to desolvation, thereby forming a light and thin SEI film. Therefore, the occurrence of negative electrode side reactions can be further reduced, the problem of lithium precipitation in the battery can be improved, and the cycle performance and overcharge resistance of the battery can be improved.

[0033] Further, in order to improve the problem of the combination of the fluoronitrile solvent and metal ions in the nickel-cobalt-manganese ternary material, the electrolyte of the present disclosure can also include an additive A. The additive A can randomly switch the coordination mode with the variable number and orientation of ligand points. It can include one or more coordination sites from the phosphorus center, has rich coordination connection ability, is conducive to its full interaction with metal ions, and the phosphorus-oxygen double bond and / or phosphorus-nitrogen double bond can make its structure skeleton more flexible and flexible, which can further improve its mutual degree with metal ions. Therefore, by adding such an additive in the electrolyte of the present disclosure, the effective combination of the electrolyte and nickel, cobalt, and manganese ions in the nickel-cobalt-manganese ternary material is strengthened, and the dissolution of manganese ions and nickel ions in the nickel-cobalt-manganese ternary material is further inhibited, thereby avoiding the destruction of the interface film of the negative electrode. In addition, the additive can also supplement the part of the positive electrode sites ignored by the fluoronitrile solvent due to the formation of an ionized sheath with lithium ions, thereby further improving the stability of the positive electrode active material.

[0034] In a specific embodiment, the additive A includes at least one of the compounds represented by the following formula (I) and formula (II):

[0035] wherein R1, R2, R3 can be the same or different, each independently selected from substituted or unsubstituted C1-C8 alkyl, substituted or unsubstituted C2-C5 alkenyl, substituted or unsubstituted C2-C4 alkynyl, substituted or unsubstituted C1-C8 alkoxy, wherein when substituted, each substituent is independently selected from phenyl, halogen, sulfur, phosphorus, silicon, methoxy, hydroxyl, carboxyl, aldehyde, carbonyl, cyano; the compound represented by formula (I) has at least one carbon-nitrogen triple bond;

[0036] R4, R5, R6, R7, R8, R9may be the same or different, each independently selected from substituted or unsubstituted C1-C8alkyl, substituted or unsubstituted C2-C5alkenyl, substituted or unsubstituted C2-C4alkynyl, substituted or unsubstituted C1-C8alkoxy, substituted or unsubstituted C6-C10aryloxy, wherein when substituted, the substituents are each independently selected from phenyl, halogen, sulfur, phosphorus, silicon group, methoxy, hydroxyl, carboxyl, aldehyde group, carbonyl, cyano. 12 R4, R5, R6, R7, R8, R9may be the same or different, each independently selected from substituted or unsubstituted C1-C8alkyl, substituted or unsubstituted C2-C5alkenyl, substituted or unsubstituted C2-C4alkynyl, substituted or unsubstituted C1-C8alkoxy, substituted or unsubstituted C6-C10aryloxy, wherein when substituted, the substituents are each independently selected from phenyl, halogen, sulfur, phosphorus, silicon group, methoxy, hydroxyl, carboxyl, aldehyde group, carbonyl, cyano.

[0037] In a preferred embodiment, the additive A comprises at least one of the following compounds: cyclotriphosphazene, tris(cyanoethyl) phosphate, ethoxy pentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene, pentafluoro(phenoxy)cyclotriphosphazene.

[0038] In addition, in order to further strengthen the protection of the additive A to the surface metal ions of the positive active material. In a specific embodiment, the mass content of the additive A is y wt%, 0.5wt%≤y wt%≤4.5wt%, based on the total mass of the electrolyte. In a specific embodiment, y wt% can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, or a range consisting of any two of these values. When the mass content of the additive A y wt% is less than 0.5wt%, the content of the additive A is too low to completely cover the transition metal on the surface of the positive electrode, which will lead to the decrease of the probability of the formation of effective combination of the additive A and transition metal nickel, cobalt, manganese ions, affecting the cycle stability of the battery; while when the mass content of the additive A y wt% is greater than 4.5wt%, the content of the additive A is too high, the complex film formed on the positive electrode is thicker, causing larger impedance between the electrodes, which is not conducive to the transmission of lithium ions, and is prone to the problem of lithium precipitation in the battery. In a preferred embodiment, 0.6wt%≤y wt%≤2.5wt%, and can be further preferred as 0.8wt%≤y wt%≤2wt%. In the present disclosure, the mass content of the additive A can be obtained by liquid chromatography test.

[0039] Further, the fluoronitrile solvent and the additive A in the electrolyte can synergistically complex on the surface of the positive active material to form a protective effect on metal ions. Specifically, when the battery encounters external factors such as high temperature, overcharging, etc., a large amount of heat will be generated inside the battery, causing the positive active material to decompose and generate active oxygen. The active oxygen generated by decomposition will also continue to generate a large amount of heat by reacting with the electrolyte, thereby causing the internal heat of the battery to increase dramatically, generating more gas, and ultimately leading to the risk of explosion of the battery. The electrolyte provided by the present disclosure can synergistically complex on the surface of the positive active material to form a protective effect on metal ions due to the simultaneous presence of the fluoronitrile solvent and the additive A, thereby further improving the high-temperature resistance and overcharge resistance of the battery. This is mainly because the fluoronitrile solvent and the additive A both have a special nitrile structure, the fluoronitrile solvent contains a carbon-nitrogen triple bond, and the additive A contains a carbon-nitrogen triple bond and / or a phosphorus-nitrogen triple bond. Such a special nitrile structure can interact with the active material on the surface of the positive electrode as an electron pair donor and an electron pair acceptor, respectively. Moreover, when the fluoronitrile solvent and the additive A are both present in the electrolyte, the nitrile structure in the additive A forms a protective layer in a point-to-point manner, and the nitrile structure in the fluoronitrile solvent forms a protective layer in a face-to-face manner, thereby synergistically improving the degree of complexation on the surface of the positive active material and enhancing the protection of the positive active material surface by the fluoronitrile solvent and the additive A. This makes the high-temperature resistance and overcharge resistance of the battery further improved effectively. Moreover, the additive A can further strengthen the protection of the transition metal nickel ions and manganese ions in the nickel-cobalt-manganese ternary material, thereby preventing the active oxygen in the positive active material from being catalyzed by the dissolved transition metal ions after escaping under heating conditions, aggravating the occurrence of side reactions in the electrolyte, and deteriorating the cycle performance of the battery.

[0040] In addition, in order to further enhance the synergistic effect of the fluoronitrile solvent and the additive A in the electrolyte, in a specific embodiment, the mass content c wt% of the fluoronitrile solvent and the mass content y wt% of the additive A satisfy the relationship 4.8≤y+c≤43 based on the total mass of the electrolyte. In a specific embodiment, y+c can be 4.8, 5, 6, 7, 8, 9, 10, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, or a range consisting of any two of these values. In a preferred embodiment, 5≤y+c≤12.

[0041] In a specific embodiment, the nickel-cobalt-manganese ternary material includes LiNi 0.3 Co 0.3 Mn 0.3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi0.5 Co 0.3 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Mn 0.3 Co 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.9 Co 0.05 Mn 0.05 at least one of O2, LiNi

[0042] In one embodiment, the positive active material further comprises a doping metal of at least one of Mg, Al, W, Zn, Ca, Fe, Ba, Sr, B, Cr, V, Zr, Ti, Sn, Mo, Ru, Si, Sb, Nb, Te.

[0043] In one embodiment, the positive active material has a gravimetric capacity of 170 mAh / g to 195 mAh / g. For example, the positive active material can have a gravimetric capacity of 170 mAh / g, 175 mAh / g, 180 mAh / g, 185 mAh / g, 190 mAh / g, 195 mAh / g. The gravimetric capacity of a positive active material refers to the amount of charge that can be stored or released by a unit mass (per gram) of the positive active material. The positive active material of the present disclosure has a high gravimetric capacity.

[0044] In one embodiment, the positive active material has a tap density of 2.8 g / cm 3 to 4.8 g / cm 3 . For example, the positive active material can have a tap density of 2.8 g / cm 3 , 3 g / cm 3 , 3.2 g / cm 3 , 3.4 g / cm 3 , 3.6 g / cm 3 , 3.8 g / cm 3 , 3.9 g / cm 3 , 4 g / cm 3 , 4.1 g / cm 3 , 4.2 g / cm 3 , 4.25 g / cm 3 , 4.3 g / cm 3 , 4.4 g / cm 3 , 4.5 g / cm 3 , 4.7 g / cm 3 , 4.8 g / cm3 In a preferred embodiment, the compaction density of the positive electrode active material is 3.8 g / cm 3 ~ 4.25 g / cm 3 A higher compaction density is more conducive to improving the energy density of the battery. The present disclosure adopts a combination design of mixing lithium cobaltate and nickel-cobalt-manganese ternary material, which does not cause the compaction density of the positive electrode active material to decrease due to the mixing of the nickel-cobalt-manganese ternary material, and enables the positive electrode active material to have high energy density and high cost performance at the same time, thereby reducing the cost of battery manufacturing.

[0045] The lithium ion battery of the present disclosure further comprises a separator and a negative electrode in addition to the positive electrode and the electrolyte. The other component materials in the positive electrode in addition to the above-mentioned materials can refer to the conventional positive and negative electrodes in the art.

[0046] According to the battery of the present disclosure, the negative electrode comprises a negative electrode active material, and the negative electrode active material comprises a carbon-based negative electrode material.

[0047] In a specific embodiment, the carbon-based negative electrode material comprises at least one of artificial graphite, natural graphite, mesocarbon microbeads, hard carbon, and soft carbon.

[0048] According to the lithium ion battery of the present disclosure, the negative electrode active material can further comprise a silicon-based negative electrode material.

[0049] In a specific embodiment, the silicon-based negative electrode material comprises at least one of a silicon-oxygen negative electrode material or a silicon-carbon negative electrode material, such as Si, SiC, SiO x (0 < x < 2).

[0050] According to the battery of the present disclosure, the separator can also use the separators commonly used in the art, such as PP film, PE film, etc.

[0051] The battery of the present disclosure can be prepared by the conventional method in the art. Specifically, the positive electrode, the separator, and the negative electrode are sequentially stacked and placed, and then the battery cell is obtained by the lamination or winding process, and then the above-mentioned battery can be obtained by the processes of baking, liquid injection, formation, packaging, etc.

[0052] Hereinafter, the positive electrode sheet and the lithium ion battery provided by the present disclosure are described in detail through specific embodiments.

[0053] Example 1

[0054] The lithium ion battery of the present disclosure is obtained by the following method:

[0055] Preparation of electrolyte

[0056] The electrolyte material of the present disclosure is obtained by the following method:

[0057] In a glove box (H2O < 0.01 ppm, O2 < 0.01 ppm, Ar atmosphere), EC, PC, PP and fluoronitrile solvent fluoronitrile compound (compound (2)) based on the total mass of the electrolyte w1 (wt%) were uniformly mixed, and then fully dried lithium hexafluorophosphate (LiPF6) was added thereto, and after dissolution, an additive A (tris(cyanoethyl) phosphate) was added in an amount of y (wt%) based on the total mass of the electrolyte, and stirred uniformly. After passing the moisture and free acid detection, the desired electrolyte was obtained.

[0058] Preparation of positive electrode sheet

[0059] The prepared positive active material (lithium cobaltate LiCoO2: nickel cobalt manganese ternary material LiNi 0.6 Mn 0.3 Co 0.1 = 8:2, wherein Ni:Co:Mn = 6.5:3.6:1.15, the mass content of nickel element is 10 wt%), conductive agent Super P, and adhesive polyvinylidene fluoride (PVDF) were dispersed in an appropriate amount of N-methyl pyrrolidone (NMP) at a weight ratio of 97:2:1, and uniformly stirred to form a uniform positive electrode slurry. The positive electrode slurry was coated on the positive electrode current collector aluminum foil, and then dried, rolled, cut to obtain the positive electrode sheet.

[0060] Preparation of negative electrode sheet

[0061] The prepared artificial graphite, conductive agent Super P, adhesive styrene butadiene rubber (SBR), and thickening agent sodium carboxymethyl cellulose (CMC) were dispersed in an appropriate amount of deionized water at a weight ratio of 97:1:1.5:0.5, and uniformly stirred to form a uniform negative electrode slurry. The negative electrode slurry was coated on the negative electrode current collector copper foil, and then dried, rolled, and cut to obtain the negative electrode sheet.

[0062] The above positive electrode, negative electrode and separator were wound into a core according to a predetermined procedure, and then subjected to welding of the tab and injection of the above electrolyte, and vacuum sealing, standing, formation and other procedures to prepare the lithium ion battery.

[0063] Example 2 group

[0064] The lithium ion batteries of the example 2 group were all manufactured by the method of example 1, except that the mass content c wt% of the fluoronitrile compound in the electrolyte was changed. For details, see Table 1.

[0065] Example 3 group

[0066] The lithium ion batteries of the example 3 group were all manufactured by the method of example 1, except that the type of the fluoronitrile compound in the electrolyte was changed. Specifically:

[0067] Example 3-1, the fluoronitrile compound is selected from compound (4);

[0068] Example 3-2, the fluoronitrile compound is selected from compound (6);

[0069] Example 3-3, the fluoronitrile compound is selected from compound (9);

[0070] Example 3-4, the fluoronitrile compound is selected from compound (15);

[0071] Example 3-5, the fluoronitrile compound is selected from compound (17).

[0072] Example 4 group

[0073] The lithium ion batteries of the Example 4 group are all manufactured by the method of Example 1, except that the mass content y wt% of the additive A is changed, which can be seen in Table 1.

[0074] Example 5 group

[0075] The lithium ion batteries of the Example 5 group are all manufactured by the method of Example 1, except that the type of the additive A is changed, which is specifically:

[0076] Example 5-1, the additive A is selected from cyclotriphosphazene;

[0077] Example 5-2, the additive A is selected from ethoxy-pentafluorocyclotriphosphazene;

[0078] Example 5-3, the additive A is selected from hexafluorocyclotriphosphazene;

[0079] Example 5-4, the additive A is selected from pentafluoro(phenoxy)cyclotriphosphazene.

[0080] Example 6 group

[0081] The lithium ion batteries of the Example 6 group are all manufactured by the method of Example 1, except that the ratio of lithium cobaltate to ternary material of nickel-cobalt-manganese in the positive active material is changed, so as to change the mass content k wt% of nickel element, which can be seen in Table 1.

[0082] Example 7 group

[0083] The lithium ion batteries of the Example 7 group are all manufactured by the method of Example 1, except that the average particle size Dv50 of the primary particles of the ternary material is changed, which is specifically:

[0084] Example 7-1, the average particle size Dv50 of the primary particles of the ternary material is changed to 0.12 μm;

[0085] Example 7-2, the average particle size Dv50 of the primary particles of the ternary material is changed to 3 μm;

[0086] Example 7-3, the average particle size Dv50 of the primary particles of the ternary material is changed to 0.1 μm;

[0087] Example 7-4, the average particle size Dv50 of the primary particles of the ternary material is changed to 6 μm;

[0088] Example 7-5, the average particle size Dv50 of the primary particles of the ternary material is changed to 8 μm.

[0089] Example 8 group

[0090] The lithium ion batteries of the Example 8 group are all manufactured by the method of Example 1, except that the specific selection of the nickel-cobalt-manganese ternary material in the positive electrode active material is changed, specifically:

[0091] Example 8-1, the nickel-cobalt-manganese ternary material is selected as LiNi 0.8 Co 0.1 Mn 0.1 O2, wherein Ni:Co:Mn = 8.4:1.3:1.14;

[0092] Example 8-2, the nickel-cobalt-manganese ternary material is selected as LiNi 0.5 Co 0.2 Mn 0.3 O2, wherein Ni:Co:Mn = 5.5:2.4:3.23;

[0093] Example 8-3, the nickel-cobalt-manganese ternary material is selected as LiNi 0.9 Co 0.05 Mn 0.05 O2, wherein Ni:Co:Mn = 9.67:0.73:0.65;

[0094] Example 8-4, the nickel-cobalt-manganese ternary material is selected as LiNi 0.3 Co 0.3 Mn 0.3 O2, wherein Ni:Co:Mn = 3.91:3.85:3.56.

[0095] Example 9

[0096] The lithium ion batteries of Example 9 are all manufactured by the method of Example 1, except that no additive A is added, which can be seen in Table 1.

[0097] Comparative Examples 1-2

[0098] The lithium ion batteries of Comparative Examples 1-2 are all manufactured by the method of Example 1, except that the ratio of lithium cobaltate to nickel-cobalt-manganese ternary material in the positive electrode active material is changed, thereby changing the mass content k wt% of nickel element, which can be seen in Table 1.

[0099] Comparative Example 3

[0100] The lithium ion battery of Comparative Example 3 was manufactured by the method of Example 1, except that no fluoronitrile compound and additive A were added to the electrolyte. See Table 1 for details.

[0101] Table 1

[0102] The mass content c of the fluoronitrile compound, the mass content y of additive A, the mass content w1 of ethylene carbonate, the mass content w2 of propylene carbonate, the mass content w3 of the carboxylic acid ester solvent, and the mass content k of nickel element in the electrolyte of the Example 5 group, the Example 7 group, and the Example 8 group of Table 1 were not changed, and therefore are not shown in Table 1.

[0103] Lithium ion battery test examples

[0104] The lithium ion batteries obtained in the above examples and comparative examples were tested by the following methods, and the test results are recorded in Table 2:

[0105] Test method for performance parameters:

[0106] (1) 25℃ battery dissection lithium test

[0107] The lithium ion battery was placed at 25℃, and charged at 1.5C constant current to the upper limit voltage (4.5V), then charged at 4.5V constant voltage to 0.05C, and rested for 5 minutes; then discharged at 1C constant current to 3V, and rested for 5 minutes, which was one charge / discharge cycle. After a certain number of charge / discharge cycles, the battery was disassembled after being taken off the platform, and the state of the negative electrode surface was observed to determine whether lithium was precipitated, which was classified into the following categories: no lithium precipitation (no lithium precipitation phenomenon on the surface of the negative electrode sheet, top and bottom, arc, and single / double surface junction), slight lithium precipitation (lithium precipitation phenomenon only on the top and bottom of the negative electrode sheet), local lithium precipitation (lithium precipitation phenomenon on the top and bottom of the negative electrode sheet, arc, and single / double surface junction), and severe lithium precipitation (lithium precipitation phenomenon on the entire surface of the negative electrode sheet).

[0108] (2) 25℃ cycle test

[0109] The lithium ion battery was placed at 25℃, and charged at 1C constant current to the upper limit voltage (4.5V), then charged at 4.5V constant voltage to 0.05C, and rested for 5 minutes; then discharged at 0.5C constant current to 3V, and rested for 5 minutes, which was one charge / discharge cycle. After a certain number of charge / discharge cycles, the capacity retention rate of the lithium ion battery at 1000T was recorded.

[0110] (3) 25℃ overcharge test

[0111] 25℃±5℃ environment, 0.2C discharge to the lower limit voltage, stand for 2 min, 0.7C constant current and constant voltage charge to the upper limit voltage, stand for 10 min, 18.5V constant voltage charging for 40h, observe whether the battery surface has fire, explosion, if there is no fire and explosion, it means pass, test 20 times, calculate the 25℃ overcharge test pass rate / %.

[0112] (4) Furnace temperature test

[0113] 25℃±5℃ environment, stand for 10 min, 0.2C discharge to the lower limit voltage; stand for 10 min, 0.7C charge to the upper limit voltage. The full battery prepared by the above examples and comparative examples is placed in an oven, and the temperature is raised at a rate of 5±2℃ / min, when the temperature in the oven reaches 130℃±2℃, the temperature is kept constant, and lasts for 60 min. After the test, observe whether the battery surface has fire, explosion, if there is no fire and explosion, it means pass, test 20 times, calculate the furnace temperature test pass rate.

[0114] Table 2

[0115] From the analysis of Table 1 and Table 2, it can be seen that the battery prepared by the part of the embodiments of the present disclosure can significantly improve the problem of lithium precipitation of the battery compared with the battery prepared by the part of the comparative examples, and has high cycle stability, high overcharge resistance and excellent safety performance; in addition, the battery prepared by the present disclosure composed of lithium cobaltate and nickel-cobalt-manganese ternary material blending can also significantly reduce the material cost, and has a wider application prospect.

[0116] The above describes the preferred embodiments of the present disclosure, but the present disclosure is not limited thereto. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present disclosure, and all belong to the protection scope of the present disclosure.

Claims

1. A battery comprising a positive electrode and an electrolyte, characterized in that, The electrolyte includes a fluoronitrile solvent; the fluoronitrile solvent is a fluoronitrile compound. The positive electrode includes a positive electrode active material, which includes lithium cobalt oxide and nickel-cobalt-manganese ternary materials. The nickel content is kwt%, with 0wt% < kwt% ≤ 24wt%, based on the total mass of the positive electrode active material.

2. The battery according to claim 1, wherein, The mass ratio of each element in the positive electrode active material is Ni:Co:Mn = (2~24):(0.5~8):(0.6~9). Preferably, Ni:Co:Mn = (4~10):(1.2~3.6):(1.13~3.37).

3. The battery according to claim 1 or 2, wherein, The average particle size Dv50 of the primary particles of the nickel-cobalt-manganese ternary material is 0.1 μm to 6 μm, preferably 0.12 μm to 3 μm.

4. The battery according to any one of claims 1-3, wherein, Based on the total mass of the electrolyte, the mass content of the fluoronitrile solvent is cwt%, 3wt% ≤ cwt% ≤ 40wt%.

5. The battery according to any one of claims 1-4, wherein, Based on the total mass of the positive electrode active material, the mass content of nickel element is kwt%, 0wt% < kwt% ≤ 15wt%.

6. The battery according to any one of claims 1-5, wherein, The electrolyte satisfies at least one of conditions (a) to (c): (a) The electrolyte includes ethylene carbonate, and the mass content of ethylene carbonate is w1wt%, w1wt%≤20wt%, preferably 0wt%≤w1wt%≤15wt% based on the total mass of the electrolyte; (b) The electrolyte comprises propylene carbonate, and the mass content of propylene carbonate is w2wt%, w2wt%≤20wt%, preferably 0wt%≤w2wt%≤15wt% based on the total mass of the electrolyte; (c) The electrolyte includes a carboxylic acid ester solvent, and the mass content of the carboxylic acid ester solvent is w3wt% based on the total mass of the electrolyte, w3wt%≤70wt%, preferably 20wt%≤w3wt%≤60wt%.

7. The battery according to claim 6, wherein, The mass content of the fluoronitrile solvent (cwt%), the mass content of the nickel element (kwt%), and the mass content of the carboxylic acid ester solvent (w3wt%) satisfy the following relationship: 56≤0.1k+0.7c+w3≤70.

8. The battery according to any one of claims 1-7, wherein, The fluoronitrile compounds include fluorinated mononitrile compounds, which include at least one of the following compounds:

9. The battery according to any one of claims 1-8, wherein, The electrolyte includes additive A, which comprises at least one of the compounds shown in formula (I) and formula (IⅠ): Wherein, R1, R2, and R3 may be the same or different, and each is independently selected from substituted or unsubstituted C1-C8 alkyl, substituted or unsubstituted C2-C5 alkenyl, substituted or unsubstituted C2-C4 alkynyl, and substituted or unsubstituted C1-C8 alkoxy groups, wherein, when substituted, each substituent is independently selected from phenyl, halogen, sulfur, phosphorus, silyl, methoxy, hydroxyl, carboxyl, aldehyde, carbonyl, and cyano groups; the compound represented by formula (Ⅰ) has at least one carbon-nitrogen triple bond; Among them, R4, R5, R6, R7, R8, and R9 may be the same or different, and each is independently selected from substituted or unsubstituted C1-C8 alkyl groups, substituted or unsubstituted C2-C5 alkenyl groups, substituted or unsubstituted C2-C4 alkynyl groups, substituted or unsubstituted C1-C8 alkoxy groups, and substituted or unsubstituted C6-C... 12 The phenoxy group, wherein, when substituted, each substituent is independently selected from phenyl, halogen, sulfur, phosphorus, silyl, methoxy, hydroxyl, carboxyl, aldehyde, carbonyl, and cyano; Preferably, additive A comprises at least one of the following compounds: cyclotriphosphazene, tri(cyanoethyl) phosphate, ethoxypentafluorocyclotriphosphazene, hexafluorocyclotriphosphazene, and pentafluoro(phenoxy)cyclotriphosphazene.

10. The battery according to claim 9, wherein, Based on the total mass of the electrolyte, the mass content of additive A is ywt%, 0.5wt% ≤ ywt% ≤ 4.5wt%.

11. The battery according to claim 10, wherein, Based on the total mass of the electrolyte, the mass content of the fluoronitrile solvent (cwt%) and the mass content of additive A (ywt%) satisfy the relationship 4.8 ≤ y + c ≤ 43.

12. The battery according to any one of claims 1-11, wherein, The nickel-cobalt-manganese ternary material includes LiNi 0.3 Co 0.3 Mn 0.3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.5 Co 0.3 Mn 0.2 O2, LiNi 0.6 Co 0.2 Mn 0.2 O2, LiNi 0.6 Mn 0.3 Co 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2, LiNi 0.9 Co 0.05 Mn 0.05 At least one of O2.

13. The battery according to any one of claims 1-12, wherein, The positive electrode active material also includes at least one of the following doped metals: Mg, Al, W, Zn, Ca, Fe, Ba, Sr, B, Cr, V, Zr, Ti, Sn, Mo, Ru, Si, Sb, Nb, Te.

14. The battery according to any one of claims 1-13, wherein, The specific capacity of the positive electrode active material is 170 mAh / g to 195 mAh / g.

15. The battery according to any one of claims 1-14, wherein, The compaction density of the positive electrode active material is 2.8 g / cm³. 3 ~4.8g / cm 3 .

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