Battery cell, battery comprising same, and electric device

Abstract

The application provides a battery monomer, a battery containing the same and a power utilization device. The battery monomer comprises a positive electrode active material, a negative electrode active material and an electrolyte, the positive electrode active material comprises a nickel-cobalt-manganese ternary material. The negative electrode active material comprises a silicon material, and the mass fraction of the silicon material in the negative electrode active material is s%. The electrolyte comprises a first additive, the first additive comprises a cyclic structure containing halogen, the mass fraction of the first additive in the electrolyte is P1%, and P1 satisfies the relationship: 1≤P1≤0.8×s‑0.12; or the electrolyte comprises the first additive, the first additive has attenuation, and the mass fraction P1% of the first additive in the electrolyte and the residual capacity q of the battery monomer satisfy the relationship: P1≤2.4×q+0.2.

Description

Technical Field

[0001] This application relates to a battery cell, a battery containing the same, and an electrical device. Background Technology

[0002] In recent years, rechargeable batteries have been widely used in energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, as well as in power tools, electric bicycles, electric motorcycles, electric cars, military equipment, aerospace, and many other fields. With the increasing application and promotion of rechargeable batteries, the requirements for their energy density and cycle performance are becoming increasingly stringent. Summary of the Invention

[0003] This application provides a battery cell, a battery containing the battery, and an electrical device thereof, wherein the battery cell can have both high energy density and good cycle performance.

[0004] The first aspect of this application provides a battery cell comprising a positive electrode active material, a negative electrode active material, and an electrolyte. The positive electrode active material comprises a nickel-cobalt-manganese ternary material. The negative electrode active material comprises silicon material, wherein the mass fraction of silicon material in the negative electrode active material is s%. The electrolyte comprises a first additive, which comprises a halogen-containing cyclic structure, and the mass fraction of the first additive in the electrolyte is P1%, wherein P1 satisfies the relationship: 1≤P1≤0.8×s-0.12; or, the electrolyte comprises the first additive, the first additive is subject to decay, and the mass fraction P1% of the first additive in the electrolyte satisfies the relationship between the remaining charge q of the battery cell and P1≤2.4×q+0.2.

[0005] It is not intended to be limited to any theory or explanation. When the positive electrode active material of a battery cell includes nickel-cobalt-manganese ternary materials, the negative electrode active material includes silicon materials, and an appropriate amount of first additive is included in the electrolyte, it can not only effectively improve the cut-off voltage of the battery, thereby improving the energy density of the secondary battery, but also extend the cycle life of the battery.

[0006] Specifically, when the electrolyte contains a first additive, the first additive can interact with the negative electrode active material, thereby preferentially forming an SEI film on the surface of the negative electrode sheet compared to organic solvents. The inventors of this application have discovered that in high-voltage silicon systems, i.e., battery systems where the positive electrode material is a high-energy-density ternary material and the negative electrode material is a silicon-based material, the first additive needs to meet specific conditions to effectively improve battery performance. Through analysis and other studies, it has been found that battery performance is significantly improved only when the first additive meets the content specified by the above-mentioned formula. The higher the content of the first additive, the denser the SEI film formed on the surface of the negative electrode sheet, and the stronger the effect of inhibiting the contact between solvent molecules and silicon materials. When the content of the first additive is too low, the thickness of the SEI film formed on the surface of the negative electrode sheet is too small, with low uniformity and density, making it difficult to inhibit side reactions between silicon materials and the electrolyte, thus shortening the battery's cycle life. However, when the content of the first additive is too high, during cycling or storage, the first additive may undergo side reactions with the electrolyte, resulting in excessive gas production and thus reducing battery reliability. Based on the above relationship, when the content of the first additive in the electrolyte and the content of silicon material in the negative electrode active material meet the ranges given in the embodiments of this application, a stable, dense, and appropriately thick SEI film can be formed on the surface of the negative electrode sheet, thereby reducing the probability of side reactions between the silicon material and the electrolyte due to volume changes during cycling. This not only reduces the irreversible loss of active lithium ions and improves the capacity utilization of the silicon material, but also enhances the cycle stability and extends the cycle life of the battery. Therefore, the battery cell provided in the embodiments of this application can possess both high energy density and high cycle life.

[0007] In any embodiment of this application, the mass fraction s% of silicon material in the negative electrode active material satisfies: 0 < s ≤ 50, and optionally, 0 < s ≤ 25. This is beneficial for further improving the energy density of the battery and extending its cycle life.

[0008] In any embodiment of this application, the first additive comprises an ester group.

[0009] Optionally, the first additive includes at least one of the compounds shown in Formula I.

[0010]

[0011] p represents 1, 2, or 3.

[0012] R 11 Represents oxygen atom or C(Y) 1 )2, Y 1Each independently includes one of the following: hydrogen atom, halogen atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aryl group with 6 to 20 carbon atoms, haloalkyl group with 1 to 20 carbon atoms, haloalkenyl group with 2 to 20 carbon atoms, haloalkynyl group with 2 to 20 carbon atoms, haloaryl group with 6 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, alkenoxy group with 2 to 20 carbon atoms, alkynoxy group with 2 to 20 carbon atoms, aryloxy group with 6 to 20 carbon atoms, haloalkoxy group with 1 to 20 carbon atoms, haloalkenoxy group with 2 to 20 carbon atoms, haloalkynoxy group with 2 to 20 carbon atoms, and haloaryloxy group with 6 to 20 carbon atoms.

[0013] R 12 R 13 R 14 R 15 Each independently includes one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloalkoxy group having 2 to 20 carbon atoms, a haloalkyneoxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms, and R 12 R 13 R 14 R 15 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

[0014] When the electrolyte contains the aforementioned first additive, it can increase the inorganic content in the negative electrode SEI film, making the SEI film more dense. This dense SEI film can restrain the expansion of silicon material during cycling. In addition, the first additive shown in Formula I has good compatibility with silicon material, which can reduce the degree of damage to the SEI film on the surface of silicon material during cycling, thereby reducing the loss of active lithium. Therefore, it is beneficial to improve the battery's capacity utilization and rate performance.

[0015] In any embodiment of this application, p represents 1 or 2.

[0016] Optionally, R 11 Represents oxygen atom or C(Y) 1 )2, Y 1 Each of the following can be independently represented: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, and propoxy.

[0017] Optionally, R 12 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy.

[0018] Optionally, R 13 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy.

[0019] Optionally, R 14 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy.

[0020] Optionally, R 15 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy.

[0021] In equation I, p and R 12 R 13 R 14 R 15 When one or more of the above conditions are met, the risk of silicon material pulverizing and deactivating due to side reactions with the electrolyte can be effectively reduced, further improving the cycle performance and storage performance of the battery.

[0022] In any embodiment of this application, the first additive includes at least one of the following compounds H1 to H6.

[0023]

[0024]

[0025] The compounds H1 to H6 mentioned above can decompose to produce an SEI film with a high content of inorganic matter, thereby improving the cycle performance of the battery.

[0026] In any embodiment of this application, the electrolyte further includes a second additive, which includes one or more boron-containing cyclic compounds.

[0027] Optionally, the second additive includes at least one of the compounds shown in Formula II-1 and Formula II-2.

[0028]

[0029] R 21 R 22 Each independently includes one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloalkoxy group having 2 to 20 carbon atoms, a haloalkyneoxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms, and R 21 R 22 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

[0030] R 23 R 24 Each can independently represent a carbonyl group C=O or C(Y) 2 )2, Y 2 Each independently comprises one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, or a haloalkyl group having 1 to 3 carbon atoms, and R 23 R 24 They do not both represent carbonyl C=O.

[0031] R 25 R 26Each independently includes one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloalkoxy group having 2 to 20 carbon atoms, a haloalkyneoxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms, and R 25 R 26 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

[0032] R 27 R 28 Each of the following is independently included: a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, or a haloalkyl group having 1 to 3 carbon atoms.

[0033] The second additive can preferentially form a denser, more stable, and lithium-ion-conducting interfacial film on the surface of the positive electrode active material compared to organic solvents. This interfacial film helps reduce the charge transfer resistance on the positive electrode side, thereby mitigating the increase in internal resistance during battery cycling and further extending the battery's cycle life.

[0034] In any embodiment of this application, R 21 It represents one of the following: hydrogen atom, methyl, ethyl, or fluoromethyl.

[0035] Optionally, R 22 It represents one of the following: hydrogen atom, methyl, ethyl, or fluoromethyl.

[0036] Optionally, R 23 It represents one of the following: hydrogen atom, methyl, ethyl, or carbonyl group.

[0037] Optionally, R 24 It represents one of the following: hydrogen atom, methyl, ethyl, or carbonyl group.

[0038] In any embodiment of this application, R 25 It represents one of the following: hydrogen atom, methyl, ethyl, or fluoromethyl.

[0039] Optionally, R 26 It represents one of the following: hydrogen atom, methyl, ethyl, or fluoromethyl.

[0040] Optionally, R 27 It represents one of the following: hydrogen atom, methyl group, or ethyl group.

[0041] Optionally, R 28 It represents one of the following: hydrogen atom, methyl group, or ethyl group.

[0042] When Formula II-1 and / or Formula II-1 satisfy one or more of the above conditions, a denser, more stable SEI film with stronger lithium-ion conduction ability can be formed on the surface of the positive electrode active material, which is beneficial to further extend the cycle life of the battery and improve the cycle stability of the battery.

[0043] In any embodiment of this application, the second additive includes at least one of the following compounds J1 to J4.

[0044]

[0045] The aforementioned compounds J1 to J4 can form a film on the positive electrode, reducing the risk of the electrolyte being oxidized and decomposed under high voltage, thereby improving the structural stability of the positive electrode active material and thus improving the cycle stability of the battery.

[0046] In any embodiment of this application, the mass content of the second additive in the electrolyte is P2%, where P2 satisfies the relationship: 0.11 + 0.01 × t ≤ P2 ≤ 1.2, where t% is the mass percentage content of the nickel-cobalt-manganese ternary material in the positive electrode film of the battery cell. This helps to improve the structural stability of the positive electrode active material, thereby improving the cycle stability of the battery.

[0047] In any embodiment of this application, 50 ≤ t < 100. When the content of nickel-cobalt-manganese ternary materials in the positive electrode film is within the above-mentioned suitable range, it is beneficial for the positive electrode active material to have both high capacity performance and high cycle stability, thereby further improving the energy density of the battery and extending the cycle life of the battery.

[0048] In any embodiment of this application, the mass content of the second additive in the electrolyte is 1:40 to 1:1, or optionally 1:5 to 1:2.

[0049] When the contents of the second additive and the first additive in the electrolyte satisfy the given relationship, it is beneficial for the second additive and the first additive to exert a synergistic effect. This not only helps reduce the initial internal resistance of the battery and the increase in internal resistance during cycling, but also helps reduce the amount of gas generated during storage, thus contributing to a longer cycle life and higher reliability of the battery.

[0050] In any embodiment of this application, the charging cut-off voltage of a single battery cell is greater than or equal to 4.2V, and optionally, the charging cut-off voltage is greater than or equal to 4.3V. This is beneficial for improving battery capacity utilization and cycle stability, thereby increasing battery energy density and extending battery cycle life.

[0051] In any embodiment of this application, the molar content of Ni element among the transition metal elements in the nickel-cobalt-manganese ternary material is less than or equal to 0.7. This is beneficial for further improving the cycle stability of the positive electrode active material, thereby extending the cycle life of the battery.

[0052] In any embodiment of this application, the positive electrode active material includes a first nickel-cobalt-manganese ternary material in which the molar content of Ni in the transition metal elements is 0.5 or more.

[0053] Optionally, the positive electrode active material also includes a second nickel-cobalt-manganese ternary material in which the molar content of Ni in the transition metal elements is less than 0.5.

[0054] Alternatively, the positive electrode active material may also include lithium-rich manganese-based positive electrode materials.

[0055] Optionally, the positive electrode active material also includes lithium phosphate-based positive electrode materials. When the positive electrode active material contains one or more of the above-mentioned positive electrode materials, it can achieve both high theoretical specific capacity and good cycle stability, thereby helping to further improve the energy density of the battery and extend its cycle life.

[0056] In any embodiment of this application, the silicon material includes at least one of nano-silicon, silicon oxide, and silicon carbide.

[0057] In any embodiment of this application, the negative electrode active material further includes a carbon material, which includes at least one of artificial graphite, natural graphite, and hard carbon. When the negative electrode active material also includes a carbon material, it is not only beneficial to flexibly adjust parameters such as the compaction density and porosity of the negative electrode film by combining silicon-based negative electrode active material particles with carbon materials, but also beneficial to improve the electron transport performance of the negative electrode, thereby improving the safety and electrochemical performance of the secondary battery.

[0058] In any embodiment of this application, the volumetric particle size Dv50 of the silicon material is 3 μm to 20 μm, and optionally, the volumetric particle size Dv50 of the silicon material is 3 μm to 15 μm. This allows the battery cells of the embodiments of this application to have high energy density.

[0059] In any embodiment of this application, the electrolyte further includes cyclic carbonates. This is beneficial for further reducing battery capacity loss and improving battery cycle stability.

[0060] In any embodiment of this application, the conductivity of the electrolyte at 25°C is 7 ms / cm to 11 ms / cm, optionally 8 ms / cm to 9 ms / cm. This is beneficial for improving the cycle performance and charging capability of the battery.

[0061] In any embodiment of this application, the viscosity of the electrolyte at 25°C is 2.5 mPa·s / cP to 5 mPa·s / cP, optionally 3 mPa·s / cP to 4 mPa·s / cP. This is beneficial for improving the cycle performance of the battery and enhancing its low-temperature charging capability.

[0062] A second aspect of this application provides a battery, including the battery cell of the first aspect of this application.

[0063] A third aspect of this application provides an electrical device, including a battery cell of the first aspect of this application or a battery of the second aspect.

[0064] The electrical device of this application includes the battery cell or battery provided in this application, and therefore has at least the same advantages as the battery cell. Attached Figure Description

[0065] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on the drawings without creative effort.

[0066] Figure 1 This is a schematic diagram of one embodiment of the battery cell provided in this application.

[0067] Figure 2 This is an exploded view of one embodiment of the battery cell provided in this application.

[0068] Figure 3 This is a schematic diagram of one embodiment of the battery module provided in this application.

[0069] Figure 4 This is a schematic diagram of one embodiment of the battery pack provided in this application.

[0070] Figure 5 yes Figure 4 An exploded view of an embodiment of the battery pack shown.

[0071] Figure 6 This is a schematic diagram of one embodiment of an electrical device that uses a battery cell provided in this application as a power source.

[0072] The accompanying drawings are not necessarily drawn to scale. The reference numerals are explained as follows: 1. Battery pack; 2. Upper casing; 3. Lower casing; 4. Battery module; 5. Individual battery cell; 51. Housing; 52. Electrode assembly; 53. Cover plate. Detailed Implementation

[0073] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the battery cell, the battery comprising it, and the power-consuming device of this application. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0074] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0075] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure of this application.

[0076] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions, and such technical solutions shall be deemed to be included in the disclosure of this application.

[0077] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0078] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0079] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0080] Unless otherwise specified, in this application, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0081] In this application, the terms "multiple", "various", etc., refer to two or more kinds.

[0082] Unless otherwise stated, the terms used in this application have the common meanings as commonly understood by those skilled in the art.

[0083] Unless otherwise stated, the values ​​of the parameters mentioned in this application can be determined using various testing methods commonly used in the art, for example, according to the testing methods given in the embodiments of this application. Unless otherwise stated, the test temperature for each parameter is 25°C.

[0084] It should be noted that in this paper, the volumetric particle size distribution (Dv50) refers to the particle size corresponding to a cumulative volumetric distribution percentage of 50%. In this application, the volumetric particle size distribution (Dv50) of the material can be determined using laser diffraction particle size analysis. For example, it can be determined using a laser particle size analyzer (e.g., Malvern MasterSize3000) in accordance with standard GB / T 19077-2016.

[0085] In this document, the term "cladding layer" refers to a layer of material covering the core, which may completely or partially cover the core. The use of "cladding layer" is for ease of description only and is not intended to limit the invention. Furthermore, each cladding layer may be a complete or partial covering.

[0086] In this document, the term "source" refers to a compound that is the source of a certain element. For example, the types of "sources" include, but are not limited to, carbonates, sulfates, nitrates, elements, halides, oxides, and hydroxides.

[0087] In this article, the terms "multiple" or "various" refer to two or more kinds.

[0088] In this document, the term "alkyl" refers to a saturated hydrocarbon group, including both straight-chain and branched structures. Examples of alkyl groups include, but are not limited to, methyl, ethyl, propyl (e.g., n-propyl, isopropyl), butyl (e.g., n-butyl, isobutyl, sec-butyl, tert-butyl), and pentyl (e.g., n-pentyl, isopentyl, neopentyl). In various embodiments, C1-C6 alkyl groups, i.e., alkyl groups, may contain 1 to 6 carbon atoms.

[0089] In this document, the term "haloalkyl" refers to a group obtained by replacing at least one hydrogen atom in an alkyl group with a halogen atom. A haloalkyl group may contain one or more halogen atoms; when multiple halogen atoms are present in a haloalkyl group, these halogen atoms may be the same or different.

[0090] In this document, the term "alkoxy" refers to an alkyl group containing an oxygen atom (-O-). Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, and propoxy. In various embodiments, C1-C6 alkoxy groups, i.e., alkoxy groups, may contain 1 to 6 carbon atoms.

[0091] In this document, the term "haloalkoxy" refers to a group obtained by replacing at least one hydrogen atom in an alkoxy group with a halogen atom. The number of halogen atoms in a haloalkoxy group can be one or more; when multiple halogen atoms are present in a haloalkoxy group, the multiple halogen atoms can be the same or different.

[0092] In this paper, a halogen atom refers to a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom. Optionally, a halogen atom may be a fluorine atom.

[0093] Throughout this specification, substituents of compounds are disclosed by groups or ranges. It is expressly intended that such descriptions include each individual sub-combination of members of these groups and ranges. For example, it is expressly intended that the term "C1-C6 alkyl" individually discloses C1, C2, C3, C4, C5, C6, C1-C6, C1-C5, C1-C4, C1-C3, C1-C2, C2-C6, C2-C5, C2-C4, C2-C3, C3-C6, C3-C5, C3-C4, C4-C6, C4-C5, and C5-C6 alkyl.

[0094] During the charging and discharging process of a battery, active lithium ions undergo insertion / extraction and consumption. The molar content of lithium in the positive electrode active material varies depending on the discharge state. In the examples of positive electrode active materials in this application, the molar content of Li refers to the initial state of the material, i.e., the state before feeding. After charge-discharge cycles, the molar content of Li changes when the positive electrode material is applied to the battery system. During the preparation of the positive electrode material, the oxygen content varies due to different process controls, such as oxygen content. In the examples of positive electrode materials in this application, the molar content of O is only a theoretical value; the actual molar content of O will fluctuate.

[0095] battery cell

[0096] Typically, a battery cell includes electrode components and an electrolyte. The electrode components include a positive electrode, a negative electrode, and a separator. During the charging and discharging process of the battery cell, active ions (such as lithium ions) repeatedly insert and extract between the positive and negative electrodes. The separator, located between the positive and negative electrodes, prevents short circuits while allowing active ions to pass through. The electrolyte, situated between the positive and negative electrodes, conducts the active ions.

[0097] The battery cell provided in the embodiments of this application includes a positive electrode active material and a negative electrode active material. The positive electrode active material includes a nickel-cobalt-manganese ternary material, and the negative electrode active material includes silicon material, with a mass fraction of silicon material of s%. In the battery cell of the embodiments of this application, the electrolyte includes a first additive, which is a halogen-containing cyclic structure. The mass fraction of the first additive in the electrolyte is P1%, and P1 satisfies the relationship: 1≤P1≤0.8×s-0.12. The first additive in the electrolyte is subject to decay, and the mass fraction P1% of the first additive in the electrolyte satisfies the relationship between the remaining charge q of the battery cell: P1≤2.4×q+0.2.

[0098] The aforementioned nickel-cobalt-manganese ternary materials may include one or more of lithium nickel-cobalt-manganese oxides and their modified compounds. The modified compounds of lithium nickel-cobalt-manganese oxides may include materials known in the art, such as doped or surface-modified lithium nickel-cobalt-manganese oxides.

[0099] The aforementioned halogen-containing cyclic structures can include halogen-containing cyclic ester compounds, and the halogen can include one or more of F, Cl, Br, and I. The halogen-containing cyclic structure can be obtained by replacing hydrogen atoms in the cyclic structure with halogen atoms, or by replacing hydrogen atoms in the cyclic structure with halogen-containing groups.

[0100] The remaining capacity mentioned above can be characterized by the state of health (SOH), which represents the percentage of a battery cell's initial capacity after full discharge. Initial capacity has a meaning known in the art and can be measured using equipment and methods known in the art. Typically, after a battery cell is manufactured, its initial capacity is measured and marked on the battery cell product. Therefore, the initial capacity of a battery cell can be determined through its markings.

[0101] Increasing the charging cutoff voltage of a battery is considered an effective way to improve its energy density. Currently, the main cathode materials for commercially available high-capacity lithium-ion batteries include nickel-cobalt-manganese ternary materials. Silicon, due to its extremely high theoretical specific capacity, far exceeding that of carbon materials, has become a highly promising anode active material. However, the volume expansion of silicon-based materials during charging can cause instability in the solid electrolyte interface (SEI) film on the anode surface, negatively impacting the capacity utilization of silicon materials and the cycle life of rechargeable batteries.

[0102] It is not intended to be limited to any theory or explanation. When the positive electrode active material of a battery cell includes nickel-cobalt-manganese ternary materials, the negative electrode active material includes silicon materials, and an appropriate amount of first additive is included in the electrolyte, it can not only effectively improve the cut-off voltage of the battery, thereby improving the energy density of the secondary battery, but also extend the cycle life of the battery.

[0103] Specifically, when the electrolyte contains a first additive, the first additive can interact with the negative electrode active material, thereby preferentially forming an SEI film on the surface of the negative electrode sheet compared to organic solvents. The inventors of this application have discovered that in high-voltage silicon systems, i.e., battery systems where the positive electrode material is a high-energy-density ternary material and the negative electrode material is a silicon-based material, the first additive needs to meet specific conditions to effectively improve battery performance. Through analysis and other studies, it has been found that battery performance is significantly improved only when the first additive meets the content specified by the above-mentioned formula. The higher the content of the first additive, the denser the SEI film formed on the surface of the negative electrode sheet, and the stronger the effect of inhibiting the contact between solvent molecules and silicon materials. When the content of the first additive is too low, the thickness of the SEI film formed on the surface of the negative electrode sheet is too small, with low uniformity and density, making it difficult to inhibit side reactions between silicon materials and the electrolyte, thus shortening the battery's cycle life. However, when the content of the first additive is too high, during cycling or storage, the first additive may undergo side reactions with the electrolyte, resulting in excessive gas production and thus reducing battery reliability. Based on the above relationship, when the content of the first additive in the electrolyte and the content of silicon material in the negative electrode active material meet the range given in the embodiments of this application, a stable, dense and appropriately thick SEI film can be formed on the surface of the negative electrode sheet, thereby reducing the probability of the silicon material undergoing a side reaction with the electrolyte due to volume changes during cycling.

[0104] The mass fraction of the first additive in the electrolyte, as described above, is P1%, and P1 satisfies the relationship: 1≤P1≤0.8×s-0.12. This refers to the mass fraction of the first additive in its original state, i.e., the amount of the first additive added before battery formation. Since the battery needs to undergo a formation process, the first additive will be consumed. During subsequent use, the first additive will further degrade. The first additive in the electrolyte exhibits degradation, and the mass fraction P1% of the first additive in the electrolyte satisfies the relationship: P1≤2.4×q+0.2. This refers to the content of the first additive under normal operating conditions after battery formation.

[0105] Therefore, it can not only reduce the irreversible loss of active lithium ions and improve the capacity utilization of silicon materials, but also improve the cycle stability of the battery and extend the cycle life of the battery.

[0106] Therefore, the battery cells provided in the embodiments of this application can have both high energy density and long cycle life.

[0107] In some embodiments, the mass fraction s% of silicon material in the negative electrode active material may satisfy: 0 < s ≤ 50. For example, the mass fraction of silicon material in the negative electrode active material may be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range of two of the above values.

[0108] Optionally, in some embodiments, the mass fraction s% of silicon material in the negative electrode active material may satisfy: 0 < s ≤ 25. For example, the mass fraction of silicon material in the negative electrode active material may be 1%, 5%, 8%, 10%, 15%, 18%, 20%, 25%, or a range of any two of the above values.

[0109] This is not intended to be limited by any theory or explanation. By adjusting the silicon content in the negative electrode active material within a given range, it is possible to achieve two goals: firstly, the negative electrode active material can have a high theoretical capacity, thus allowing the battery to have a high energy density; secondly, it can ensure that the content of the first additive in the electrolyte is appropriate, thereby reducing the risk of excessive gas generation during battery cycling or storage. This, in turn, helps to further improve the battery's energy density and extend its cycle life.

[0110] In some embodiments, the first additive may contain an ester group.

[0111] Optionally, in some embodiments, the first additive may include at least one of the compounds shown in Formula I.

[0112]

[0113] In Equation I, p can represent 1, 2, or 3.

[0114] R 11 It can represent an oxygen atom or C(Y) 1 )2, Y 1 Each independently includes one of the following: hydrogen atom, halogen atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aryl group with 6 to 20 carbon atoms, haloalkyl group with 1 to 20 carbon atoms, haloalkenyl group with 2 to 20 carbon atoms, haloalkynyl group with 2 to 20 carbon atoms, haloaryl group with 6 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, alkenoxy group with 2 to 20 carbon atoms, alkynoxy group with 2 to 20 carbon atoms, aryloxy group with 6 to 20 carbon atoms, haloalkoxy group with 1 to 20 carbon atoms, haloalkenoxy group with 2 to 20 carbon atoms, haloalkynoxy group with 2 to 20 carbon atoms, and haloaryloxy group with 6 to 20 carbon atoms.

[0115] R 12 R 13 R14 R 15 Each of these can independently include one of the following: hydrogen atom, halogen atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aryl group with 6 to 20 carbon atoms, haloalkyl group with 1 to 20 carbon atoms, haloalkenyl group with 2 to 20 carbon atoms, haloalkynyl group with 2 to 20 carbon atoms, haloaryl group with 6 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, alkenoxy group with 2 to 20 carbon atoms, alkynoxy group with 2 to 20 carbon atoms, aryloxy group with 6 to 20 carbon atoms, haloalkoxy group with 1 to 20 carbon atoms, haloalkenoxy group with 2 to 20 carbon atoms, haloalkynoxy group with 2 to 20 carbon atoms, and haloaryloxy group with 6 to 20 carbon atoms, and R 12 R 13 R 14 R 15 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

[0116] When the electrolyte contains the first additive shown in Formula I, it can increase the inorganic content in the negative electrode SEI film, making the SEI film more dense. This dense SEI film can restrain the expansion of silicon material during cycling. In addition, the first additive shown in Formula I has good compatibility with silicon material, which can reduce the degree of damage to the SEI film on the surface of silicon material during cycling, thereby reducing the loss of active lithium. Therefore, it is beneficial to improve the battery's capacity utilization and rate performance.

[0117] In some embodiments, in formula I above, p can represent 1 or 2.

[0118] In some embodiments, R 11 It can represent an oxygen atom or C(Y) 1 )2, Y 1 Each can independently represent one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, and propoxy.

[0119] In some embodiments, R 12 It can represent one of the following: hydrogen atom, fluorine atom, methyl, ethyl, fluoromethyl, or methoxy.

[0120] In some embodiments, R 13It can represent one of the following: hydrogen atom, fluorine atom, methyl, ethyl, fluoromethyl, or methoxy.

[0121] In some embodiments, R 14 It can represent one of the following: hydrogen atom, fluorine atom, methyl, ethyl, fluoromethyl, or methoxy.

[0122] In some embodiments, R 15 It can represent one of the following: hydrogen atom, fluorine atom, methyl, ethyl, fluoromethyl, or methoxy.

[0123] In some embodiments, R 12 R 13 R 14 R 15 Each can independently represent one of the following: hydrogen atom, fluorine atom, methyl, ethyl, fluoromethyl, methoxy, and R. 12 R 13 R 14 R 15 At least one of them includes a fluorine atom or a fluoromethyl group.

[0124] It is not intended to be limited to any theory or explanation, when in Equation I, p, R 12 R 13 R 14 R 15 When one or more of the above conditions are met, a denser, more stable, and more lithium-ion-conducting SEI film can be formed on the surface of the negative electrode active material. Even after long-term charge and discharge, the SEI film can still effectively inhibit the contact between the negative electrode active material and the electrolyte, thereby effectively reducing the risk of silicon material pulverizing and deactivating due to side reactions with the electrolyte, and further improving the cycle performance and storage performance of the battery.

[0125] In some embodiments, the first additive may include at least one of compounds H1 to H6.

[0126]

[0127]

[0128] Not intended to be limited by any theory or explanation, the aforementioned compounds H1 to H6 can decompose to produce an SEI film with a high content of inorganic matter, thereby improving the cycle performance of the battery.

[0129] In some embodiments, the electrolyte may further include a second additive, which may include one or more boron-containing cyclic compounds.

[0130] In some embodiments, the second additive may include at least one of the compounds shown in Formula II-1 and Formula II-2.

[0131]

[0132] In Equation II-1, R 21 R 22 Each of these can independently include one of the following: hydrogen atom, halogen atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aryl group with 6 to 20 carbon atoms, haloalkyl group with 1 to 20 carbon atoms, haloalkenyl group with 2 to 20 carbon atoms, haloalkynyl group with 2 to 20 carbon atoms, haloaryl group with 6 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, alkenoxy group with 2 to 20 carbon atoms, alkynoxy group with 2 to 20 carbon atoms, aryloxy group with 6 to 20 carbon atoms, haloalkoxy group with 1 to 20 carbon atoms, haloalkenoxy group with 2 to 20 carbon atoms, haloalkynoxy group with 2 to 20 carbon atoms, and haloaryloxy group with 6 to 20 carbon atoms, and R 21 R 22 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

[0133] R 23 R 24 Each can independently represent a carbonyl group C=O or C(Y). 2 )2, Y 2 Each may independently include one of the following: hydrogen atom, halogen atom, alkyl group having 1 to 3 carbon atoms, or haloalkyl group having 1 to 3 carbon atoms, and R 23 R 24 They do not both represent carbonyl C=O.

[0134] In Equation II-2, R 25 R 26Each of these can independently include one of the following: hydrogen atom, halogen atom, alkyl group with 1 to 20 carbon atoms, alkenyl group with 2 to 20 carbon atoms, alkynyl group with 2 to 20 carbon atoms, aryl group with 6 to 20 carbon atoms, haloalkyl group with 1 to 20 carbon atoms, haloalkenyl group with 2 to 20 carbon atoms, haloalkynyl group with 2 to 20 carbon atoms, haloaryl group with 6 to 20 carbon atoms, alkoxy group with 1 to 20 carbon atoms, alkenoxy group with 2 to 20 carbon atoms, alkynoxy group with 2 to 20 carbon atoms, aryloxy group with 6 to 20 carbon atoms, haloalkoxy group with 1 to 20 carbon atoms, haloalkenoxy group with 2 to 20 carbon atoms, haloalkynoxy group with 2 to 20 carbon atoms, and haloaryloxy group with 6 to 20 carbon atoms, and R 25 R 26 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

[0135] R 27 R 28 Each of these can independently include one of the following: hydrogen atom, halogen atom, alkyl group having 1 to 3 carbon atoms, or haloalkyl group having 1 to 3 carbon atoms.

[0136] Not intended to be limited by any theory or explanation, the second additive can preferentially form a denser, more stable, and lithium-ion-conducting interfacial film on the surface of the positive electrode active material compared to organic solvents. This interfacial film helps reduce the charge transfer resistance on the positive electrode side, thereby mitigating the increase in internal resistance during battery cycling and further extending the battery's cycle life.

[0137] In some embodiments, in formula II-1, R 21 It can represent one of hydrogen atom, methyl, ethyl, or fluoromethyl.

[0138] Optionally, R 22 It can represent one of hydrogen atom, methyl, ethyl, or fluoromethyl.

[0139] Optionally, R 23 It can represent one of the following: hydrogen atom, methyl, ethyl, or carbonyl group.

[0140] Optionally, R 24 It can represent one of the following: hydrogen atom, methyl, ethyl, or carbonyl group.

[0141] In some embodiments, in formula II-2, R 25It can represent one of hydrogen atom, methyl, ethyl, or fluoromethyl.

[0142] Optionally, R 26 It can represent one of hydrogen atom, methyl, ethyl, or fluoromethyl.

[0143] Optionally, R 27 It can represent one of hydrogen atoms, methyl, or ethyl.

[0144] Optionally, R 28 It can represent one of hydrogen atoms, methyl, or ethyl.

[0145] Not intended to be limited to any particular theory or explanation, when Formula II-1 and / or Formula II-1 satisfy one or more of the above conditions, a denser, more stable SEI film with stronger lithium-ion conductivity can be formed on the surface of the positive electrode active material. This effectively reduces the oxidation reaction of the electrolyte on the positive electrode surface and further slows down the increase in internal resistance of the battery during cycling. Therefore, it is beneficial to further extend the cycle life of the battery and improve its cycle stability.

[0146] In some embodiments, the second additive may include at least one of the following compounds J1-J4.

[0147]

[0148]

[0149] Not intended to be limited by any theory or explanation, the aforementioned compounds J1 to J4 can form a film on the positive electrode, reducing the risk of the electrolyte being oxidized and decomposed under high voltage, thereby improving the structural stability of the positive electrode active material and thus improving the cycle stability of the battery.

[0150] In some embodiments, the mass content of the second additive in the electrolyte is P2%, where P2 satisfies the relationship: 0.11 + 0.01 × t ≤ P2 ≤ 1.2, where t% is the mass percentage of nickel-cobalt-manganese ternary materials in the positive electrode slurry film layer of the battery cell. This helps to improve the structural stability of the positive electrode active material, thereby improving the cycle stability of the battery.

[0151] In some embodiments, 50 ≤ t < 100.

[0152] It is not intended to be limited by any theory or explanation. When the content of nickel-cobalt-manganese ternary materials in the positive electrode film is within the above-mentioned appropriate range, it is beneficial for the positive electrode active material to have both high capacity performance and high cycle stability, thereby helping to further improve the energy density of the battery and extend the cycle life of the battery.

[0153] In some embodiments, the mass ratio of the second additive in the electrolyte to the mass content of the first additive in the electrolyte can be 1:40 to 1:1, for example, 1:40 to 1:1, 1:30 to 1:1, 1:20 to 1:1, 1:10 to 1:1, 1:5 to 1:1, 1:4 to 1:1, 1:3 to 1:1, 1:2 to 1:1, 1:1.5 to 1:1, 1:1.2 to 1:1.

[0154] Optionally, in some embodiments, the mass ratio of the second additive in the electrolyte to the mass content of the first additive in the electrolyte can be 1:5 to 1:2, 1:4.5 to 1:2, 1:4 to 1:2, 1:3.5 to 1:2, 1:3 to 1:2, 1:2.5 to 1:2, 1:5 to 1:3, 1:4.5 to 1:3, 1:4 to 1:3, 1:4.5 to 1:3, or 1:5 to 1:4.

[0155] This is not intended to be limited to any theory or explanation, but when the contents of the second and first additives in the electrolyte satisfy the given relationship, it is beneficial for the second and first additives to exert a synergistic effect. This not only helps reduce the initial internal resistance of the battery and the increase in internal resistance during cycling, but also helps reduce the amount of gas generated during storage, thus contributing to a longer cycle life and higher reliability.

[0156] In some embodiments, the charging cutoff voltage of a single battery cell can be greater than or equal to 4.2V, for example, it can be 4.2V, 4.25V, 4.3V, 4.35V, 4.4V, 4.45V, 4.5V, or a range of any two of the above values.

[0157] Optionally, in some embodiments, the charging cutoff voltage of a single battery cell may be greater than or equal to 4.3V, for example, it may be 4.3V, 4.35V, 4.4V, 4.45V, 4.5V, or a range of any two of the above values.

[0158] Not intended to be limited to any theory or explanation, the electrolyte of the battery cell provided in this application embodiment includes a first additive, which is beneficial for forming a dense and stable SEI film on the negative electrode surface. Optionally, the electrolyte of the battery cell provided in this application embodiment may further include a second additive, thereby facilitating the formation of a dense and stable interface film on the positive electrode surface. This improves the stability of the electrode active material structure and the stability of the electrode surface interface film, allowing the battery cell to undergo charge-discharge cycles at higher charging cut-off voltages. This, in turn, improves the battery's capacity utilization and cycle stability, thereby increasing the battery's energy density and extending its cycle life.

[0159] In some embodiments, the molar content of Ni in the transition metal elements in the nickel-cobalt-manganese ternary material may be less than or equal to 0.7. For example, the molar content of Ni in the transition metal elements may be 0.7, 0.65, 0.6, 0.55, 0.5, 0.45, 0.4, 0.35, 0.3, 0.25, 0.2, 0.15, 0.1, or a range of any two of the above values. The statement that the molar content of Ni in the transition metal elements is less than or equal to 0.7 indicates that, based on the total molar amount of the transition metal elements, the molar content of Ni in the transition metal elements in the nickel-cobalt-manganese ternary material is less than or equal to 0.7. As an example, when the nickel-cobalt-manganese ternary material is an undoped nickel-cobalt-manganese ternary material, the molar content of Ni in the transition metal elements being less than or equal to 0.7 can be expressed as: the value of the molar amount of Ni / (molar amount of Ni + molar amount of Cobalt + molar amount of Manganese) is less than or equal to 0.7. For example, nickel-cobalt-manganese ternary materials with a Ni molar content of less than or equal to 0.7 in the transition metal elements can include LiNi. 0.6 Co 0.2 Mn 0.2 O2 (NCM622), etc.

[0160] In nickel-cobalt-manganese ternary materials, the molar content of Ni among transition metal elements meets the given range, which is beneficial to further improve the cycle stability of the positive electrode active material, thereby helping to extend the cycle life of the battery.

[0161] In some embodiments, the positive electrode active material may include a first nickel-cobalt-manganese ternary material in which the molar content of Ni in the transition metal element is 0.5 or more. As an example, the first nickel-cobalt-manganese ternary material may include Li… x Ni a Co b Mn c M y O2 and Li x Ni a Co b Mn c M y At least one of the composite materials obtained by doping and / or surface modification of O2, wherein 1.05≥x>0.9, 1>a≥0.5, 0.1≥b>0, 0.5≥c≥0, 0.05≥y≥0, and M includes one or more of Ti, Al, Zr, Mg, Zn, Ba, Mo, and B.

[0162] Optionally, in some embodiments, the positive electrode active material may further include a second nickel-cobalt-manganese ternary material in which the molar content of Ni in the transition metal element is less than 0.5. As an example, the second nickel-cobalt-manganese ternary material may include Li… x1 Nia1 Co b1 Mn c1 M 1 y1 O2 and Li x1 Ni a1 Co b1 Mn c1 M 1 y1 At least one of the composite materials obtained by doping and / or surface modification of O2, wherein 1.05≥x1>0.9, 0.5>a1≥0.2, 0.1≥b1>0, 0.8≥c1≥0.35, 0.05≥y1≥0, M 1 It includes one or more of Ti, Al, Zr, Mg, Zn, Ba, Mo, and B.

[0163] Optionally, in some embodiments, the positive electrode active material may further include a lithium-rich manganese-based positive electrode material. As an example, the lithium-rich manganese-based positive electrode material may include Li... x2 Ni a2 Co b2 Mn c2 M 2 y2 O2 and Li x2 Ni a2 Co b2 Mn c2 M 2 y2 At least one of the composite materials obtained by doping and / or surface modification of O2, wherein 1.25≥x²>1.05, 0.7≥a²≥0, 0.2≥b²≥0, 0.7≥c²>0.4, 0.1≥y²≥0, M 2 It includes one or more of Ti, Al, Nb, Zr, Mg, Zn, W, Na, Cr, Cd, K, Cu, Fe, Ba, Mo, B, F, Cl, and Si, and optionally, 0.5 ≥ a² > 0 and 0.15 ≥ b² ≥ 0.

[0164] Optionally, in some embodiments, the positive electrode active material may further include a lithium phosphate-based positive electrode material. As an example, the lithium phosphate-based positive electrode material may include Li... x3 Fe d Mn c3 M 3 y3 PO4 or Li x3 Fe d Mn c3 M 3 y3At least one of the following composite materials obtained by doping and / or surface modification of PO4, wherein 1 ≥ x3 > 0.9, 1 ≥ c3 ≥ 0, 0.1 ≥ y3 ≥ 0, 1 ≥ d ≥ 0, M 3 It includes one or more transition metal elements other than Fe and Mn, as well as non-transition metal elements.

[0165] The first type of nickel-cobalt-manganese ternary material, the second type of nickel-cobalt-manganese ternary material, the lithium-rich manganese-based cathode material, and the lithium phosphate-containing cathode material mentioned above can be disposed on one or both sides of the current collector by mixing or layering.

[0166] As an example, the positive electrode active material may include LiNi. 0.6 Co 0.2 Mn 0.2 O2 (NCM622). Optionally, the positive electrode active material may further include LiNi. 0.8 Co 0.1 Mn 0.1 O2 (NCM811), Li 1.2 Co 0.13 Ni 0.13 Mn 0.54 O2(LRM114), Li 1.15 Co 0.09 Ni 0.18 Mn 0.55 O2, Li 1.11 Ni 0.3 Mn 0.6 O2, Li 1.15 Co 0.03 Ni 0.18 Mn 0.55 O2, LiFePO4, LiMnPO4, LiMn 1-x4 Fe x4 One or more of PO4, where 1 > x4 > 0.

[0167] It is not intended to be limited by any theory or explanation. When the positive electrode active material contains one or more of the above-mentioned positive electrode materials, it can enable the positive electrode active material to have both high theoretical specific capacity and good cycle stability, which is conducive to further improving the energy density of the battery and extending the cycle life of the battery.

[0168] In some embodiments, the silicon material may include at least one of nano-silicon, silicon oxide, and silicon carbide.

[0169] In some embodiments, the negative electrode active material may further include carbon materials, which may include at least one of artificial graphite, natural graphite, and hard carbon. When the negative electrode active material also includes carbon materials, it is not only beneficial to flexibly adjust parameters such as the compaction density and porosity of the negative electrode film by combining silicon-based negative electrode active material particles with carbon materials, but also beneficial to improve the electron transport performance of the negative electrode, thereby improving the safety and electrochemical performance of the secondary battery.

[0170] In some embodiments, the volume distribution particle size Dv50 of the silicon material can be 3μm to 20μm, for example, it can be 3μm, 5μm, 8μm, 10μm, 12μm, 15μm, 18μm, 20μm, or any range of two of the above values.

[0171] Optionally, in some embodiments, the volume distribution particle size Dv50 of the silicon material can be 3μm to 15μm, for example, it can be 3μm, 4μm, 5μm, 8μm, 10μm, 12μm, 14μm, 15μm, or any range of two of the above values.

[0172] Not intended to be limited by any theory or explanation, when silicon materials have a large volumetric particle size distribution, they generally exhibit higher specific capacity. However, correspondingly, the volume expansion effect of silicon materials is also amplified. In the battery cell provided in this application embodiment, the presence of the first additive helps to form a stable and dense SEI film on the surface of the negative electrode active material. Therefore, when the silicon material undergoes volume expansion, the SEI film can effectively inhibit the contact between the silicon material and the electrolyte, thereby reducing the risk of silicon material pulverizing and deactivating due to side reactions. Thus, the use of the aforementioned silicon material with a larger particle size in the battery cell of this application embodiment is permitted, thereby allowing the battery cell of this application embodiment to possess a high energy density.

[0173] The volumetric particle size distribution (Dv50) of silicon materials has a well-known meaning in the art; it represents the particle size corresponding to the cumulative particle size distribution percentage of silicon materials reaching 50% in a volumetric particle size distribution. The volumetric particle size distribution (Dv50) can be determined using equipment and methods known in the art. For example, it can be determined using a laser particle size analyzer (e.g., Malvern Master Size 3000) according to GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method.

[0174] In some embodiments, the electrolyte may further include cyclic carbonates. When the electrolyte also includes cyclic carbonates, it helps the first additive to form a stable and dense SEI film on the surface of the negative electrode active material, thereby further reducing battery capacity loss and improving battery cycle stability.

[0175] In some embodiments, at 25°C, the conductivity of the electrolyte can be 7 ms / cm to 11 ms / cm, for example, it can be 7 ms / cm, 8 ms / cm, 9 ms / cm, 10 ms / cm, 11 ms / cm, or any range of two of the above values.

[0176] Optionally, in some embodiments, the conductivity of the electrolyte at 25°C can be 8 ms / cm to 9 ms / cm, for example, it can be 8 ms / cm, 8.2 ms / cm, 8.4 ms / cm, 8.6 ms / cm, 8.8 ms / cm, 9 ms / cm, or any range of two of the above values.

[0177] It is not intended to be limited to any theory or explanation. When the conductivity of the electrolyte meets the given range, it is beneficial to improve the cycle performance of the battery and improve the charging capability of the battery.

[0178] The conductivity of an electrolyte has a meaning known in the art and can be determined using equipment and methods known in the art. For example, it can be determined using a conductivity meter, referring to HG / T 4066-4067-2008.

[0179] In some embodiments, at 25°C, the viscosity of the electrolyte can be 2.5 mPa·s / cP to 5 mPa·s / cP, for example, it can be 2.5 mPa·s / cP, 3 mPa·s / cP, 3.5 mPa·s / cP, 4 mPa·s / cP, 4.5 mPa·s / cP, 5 mPa·s / cP, or any range of two of the above values.

[0180] Optionally, in some embodiments, the viscosity of the electrolyte at 25°C can also be 3 mPa·s / cP to 4 mPa·s / cP, 3.2 mPa·s / cP to 4 mPa·s / cP, 3.5 mPa·s / cP to 4 mPa·s / cP, 3.8 mPa·s / cP to 4 mPa·s / cP, 3 mPa·s / cP to 3.8 mPa·s / cP, 3.2 mPa·s / cP to 3.8 mPa·s / cP, 3.5 mPa·s / cP to 3.8 mPa·s / cP, 3 mPa·s / cP to 3.5 mPa·s / cP, 3.2 mPa·s / cP to 3.5 mPa·s / cP, or 3 mPa·s / cP to 3.2 mPa·s / cP.

[0181] It is not intended to be limited to any theory or explanation, but when the viscosity of the electrolyte meets the given range, it is beneficial to improve the cycle performance of the battery and improve the battery's low-temperature charging capability.

[0182] The viscosity of the electrolyte has a meaning known in the art and can be determined using equipment and methods known in the art. For example, it can be determined using a viscometer, such as the DV-2TLV model, in accordance with SJ / T 11723-2018.

[0183] In some embodiments of the present application, the positive electrode of the battery cell may include a positive current collector and a positive electrode film layer disposed on at least one surface of the positive current collector and comprising a positive electrode active material. For example, the positive current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposite surfaces of the positive current collector.

[0184] In some embodiments, the positive electrode film may optionally include a positive electrode conductive agent. This application does not impose any particular limitation on the type of positive electrode conductive agent. As an example, the positive electrode conductive agent includes at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0185] In some embodiments, the positive electrode film layer may optionally include a positive electrode binder. This application does not impose any particular limitation on the type of positive electrode binder. As an example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0186] In some embodiments, the positive current collector may be a metal foil or a composite current collector. An example of a metal foil is aluminum foil. The composite current collector may include a polymer substrate and a metal layer formed on at least one surface of the polymer substrate. An example of a metal material may be at least one selected from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. An example of a polymer substrate may be at least one selected from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0187] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, followed by drying and cold pressing. The positive electrode slurry is usually formed by dispersing the positive electrode active material, optional conductive agent, optional binder, and any other components in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP), but is not limited to it.

[0188] In some embodiments of the present application, in a single battery cell, the negative electrode sheet of the electrode assembly may include a negative electrode current collector and a negative electrode film layer disposed on at least one surface of the negative electrode current collector and comprising a negative electrode active material. For example, the negative electrode current collector has two surfaces opposite to each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposite surfaces of the negative electrode current collector.

[0189] In some embodiments, the negative electrode film layer may optionally include a negative electrode conductive agent. This application does not impose any particular limitation on the type of negative electrode conductive agent. As an example, the negative electrode conductive agent may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0190] In some embodiments, the negative electrode film layer may optionally include a negative electrode binder. This application does not impose any particular limitation on the type of negative electrode binder. As an example, the negative electrode binder may include at least one of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, waterborne acrylic resins (e.g., polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0191] In some embodiments, the negative electrode film may optionally include other additives. As an example, other additives may include thickeners, such as sodium carboxymethyl cellulose (CMC), PTC thermistor materials, etc.

[0192] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As an example of a metal foil, copper foil may be used. The composite current collector may include a polymeric material substrate and a metal material layer formed on at least one surface of the polymeric material substrate. As an example, the metal material may include at least one of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. As an example, the polymeric material substrate may include at least one of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0193] The negative electrode film is typically formed by coating a negative electrode slurry onto a negative electrode current collector, followed by drying and cold pressing. The negative electrode slurry is usually formed by dispersing the negative electrode active material, optional conductive agent, optional binder, and other optional additives in a solvent and stirring until homogeneous. The solvent can be N-methylpyrrolidone (NMP) or deionized water, but is not limited to these.

[0194] The negative electrode sheet does not exclude other additional functional layers besides the negative electrode film layer. For example, in some embodiments, the negative electrode sheet also includes a conductive undercoat layer (e.g., composed of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and disposed on the surface of the negative electrode current collector. In some embodiments, the negative electrode sheet of this application also includes a protective layer covering the surface of the negative electrode film layer.

[0195] In this application embodiment, there are no particular restrictions on the type of separator used in the electrode assembly of the battery cell. Any well-known porous separator with good chemical and mechanical stability can be selected.

[0196] In some embodiments, the material of the separator may include at least one selected from glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different.

[0197] In some embodiments, the positive electrode, the separator, and the negative electrode can be fabricated into an electrode assembly using a winding process or a stacking process.

[0198] In the battery cell of this application embodiment, the electrolyte includes an electrolyte salt and a solvent. The types of electrolyte salt and solvent are not specifically limited and can be selected according to actual needs.

[0199] As an example, the electrolyte salt may include, but is not limited to, at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0200] As an example, the solvent may include, but is not limited to, at least one of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butyl ester carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0201] In some embodiments, the electrolyte may optionally include other additives. For example, the additives may include additives that can improve certain battery performance, such as additives that improve battery overcharge performance, additives that improve battery high-temperature performance, additives that improve battery low-temperature power performance, etc.

[0202] In some embodiments, the positive electrode, the separator, and the negative electrode can be fabricated into an electrode assembly by a winding process and / or a stacking process.

[0203] In some embodiments, the battery cell may include an outer packaging. This outer packaging may be used to encapsulate the electrode assembly and electrolyte described above.

[0204] In some embodiments, the outer packaging of the battery cell can be a rigid shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the battery cell can also be a soft pack, such as a pouch. The material of the soft pack can be plastic, such as at least one of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0205] This application does not impose any particular limitation on the shape of the battery cell; it can be cylindrical, square, or any other arbitrary shape. Figure 1 The example shown is a square-structured battery cell 5.

[0206] In some embodiments, such as Figure 2 As shown, the outer packaging may include a housing 51 and a cover 53. The housing 51 may include a base plate and side plates connected to the base plate, the base plate and side plates enclosing a receiving cavity. The housing 51 has an opening communicating with the receiving cavity, and the cover 53 is used to cover the opening to close the receiving cavity. The positive electrode, negative electrode, and separator may be formed into an electrode assembly 52 by a winding process and / or a stacking process. The electrode assembly 52 is encapsulated in the receiving cavity. Electrolyte is immersed in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 may be one or more, which can be adjusted according to requirements.

[0207] The methods for preparing battery cells are well known. In some embodiments, a positive electrode, a separator, a negative electrode, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode, separator, and negative electrode can be formed into an electrode assembly through a winding process and / or a stacking process. The electrode assembly is placed in an outer packaging, dried, and then injected with an electrolyte. After vacuum sealing, settling, formation, and shaping processes, a battery cell is obtained.

[0208] Battery

[0209] The battery mentioned in the embodiments of this application may be a single physical module comprising one or more battery cells to provide higher voltage and capacity. When there are multiple battery cells, the multiple battery cells are connected in series, parallel, or mixed via a busbar.

[0210] In some embodiments, the battery can be a battery module; when there are multiple battery cells, the multiple battery cells are arranged and fixed to form a battery module. Figure 3 This is a schematic diagram of battery module 4 as an example. Figure 3 As shown, in the battery module 4, multiple battery cells 5 can be arranged sequentially along the length of the battery module 4. Of course, they can also be arranged in any other manner. Furthermore, the multiple battery cells 5 can be fixed in place using fasteners. Optionally, the battery module 4 may also include a housing with a receiving space in which the multiple battery cells 5 are received.

[0211] In some embodiments, the battery can be a battery pack, which includes a housing and individual battery cells. The individual battery cells or battery modules are housed in the housing, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0212] Figure 4 and Figure 5 This is a schematic diagram of battery pack 1 as an example. Figure 4 and Figure 5 As shown, the battery pack 1 may include a battery box and multiple battery modules 4 disposed within the battery box. The battery box includes an upper body 2 and a lower body 3. The upper body 2 covers the lower body 3, forming a closed space for accommodating the battery modules 4. The multiple battery modules 4 can be arranged in any manner within the battery box.

[0213] Electrical appliances

[0214] This application also provides an electrical device, which includes a battery cell or battery provided in the embodiments of this application. The battery cell or battery can be used as a power source for the electrical device or as an energy storage unit for the electrical device. The electrical device can be, but is not limited to, mobile devices (e.g., mobile phones, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0215] Electrical devices can select individual battery cells or batteries according to their usage requirements.

[0216] Figure 6 This is a schematic diagram of an example electrical device. The device could be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the device's requirements for high power and high energy density, a battery pack or battery module can be used.

[0217] Another example of an electrical device could be a mobile phone, tablet, or laptop. These devices typically require a slim and lightweight design and can use a single battery cell as their power source.

[0218] Example

[0219] The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on mass, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0220] Example 1

[0221] Preparation of positive electrode sheet

[0222] LiNi, the positive electrode active material 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiFePO4, conductive carbon black (Super P), and binder polyvinylidene fluoride (PVDF) are mixed evenly in an appropriate amount of solvent N-methylpyrrolidone (NMP) at a mass ratio of 35:61.2:2.7:1.1 to obtain a positive electrode slurry. The positive electrode slurry is coated onto a positive electrode current collector aluminum foil, and the positive electrode sheet is obtained through processes such as drying, cold pressing, slitting, and cutting.

[0223] Preparation of negative electrode sheet

[0224] The negative electrode active material silica, artificial graphite, conductive agent carbon black (Super P), binder styrene-butadiene rubber (SBR) and sodium carboxymethyl cellulose (CMC) are mixed evenly in an appropriate amount of deionized water at a mass ratio of 1.4:95:0.7:1.8:1.1 to obtain a negative electrode slurry. The negative electrode slurry is coated on the negative electrode current collector copper foil, and the negative electrode sheet is obtained through drying, cold pressing, slitting and cutting processes.

[0225] Preparation of the separating membrane

[0226] Polypropylene film is used as the separator.

[0227] Preparation of electrolyte

[0228] An organic solvent was prepared by mixing the first additive H1, ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) in a mass ratio of 1:54:30:15. The fully dried LiPF6 was then dissolved in the organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0229] Preparation of secondary batteries

[0230] The positive electrode, separator, and negative electrode are stacked and wound in sequence to obtain an electrode assembly. The electrode assembly is placed in an outer packaging, dried, and then injected with electrolyte. After vacuum sealing, settling, formation, and shaping, a secondary battery is obtained.

[0231] The secondary batteries in Examples 2-23 and Comparative Examples 1-3 are similar to those in Example 1, except that the electrolyte preparation parameters, the content of NCM811, or the content of silicon suboxide were adjusted, as detailed in Table 1. The first additives H1-H6 and the second additives J1-J4 are shown in the following formulas.

[0232]

[0233]

[0234] Test section

[0235] (1) Room temperature cycling performance test

[0236] At 25°C, the secondary battery is charged to 4.3V at a constant current of 0.33C, then charged to 0.05C at a constant voltage of 4.3V. After resting for 5 minutes, it is discharged to 3.0V at 0.33C. The resulting capacity is recorded as the initial capacity C0. The above steps are repeated for the same battery, and the discharge capacity Cn of the battery after each cycle is recorded. When Cn / C0×100%≤80%, the corresponding number of cycles is recorded.

[0237] (2) Battery DC internal resistance (DCR) test

[0238] At 25℃, the secondary battery was charged at a constant current of 0.33C to 4.3V, then charged at a constant voltage of 4.3V to a current of 0.05C. After resting for 5 minutes, the voltage V1 was recorded in the last second of the resting period. Then, it was discharged at 4C for 30 seconds, and the voltage V2 was recorded in the last second of the discharge period. The initial DCR was calculated as (V2 - V1) / the current corresponding to the 4C rate. The above steps were repeated for the same battery every 100 cycles, and the DCR on the 100th cycle was calculated. Cyclic DCR growth (%) = (DCR on the 100th cycle - Initial DCR) / Initial DCR × 100%.

[0239] The test results are detailed in Table 2.

[0240] Table 1

[0241]

[0242] Table 2

[0243]

[0244] The remaining charge of the battery cells in Examples 1 and 4, as well as the mass fraction of the first additive in the electrolyte, were monitored. When the remaining charge of the battery cell was 70%, the mass fraction of the first additive in the electrolyte (P1% under operating conditions) is shown in Table 3.

[0245] Table 3

[0246]

[0247] The test results in Tables 1 to 3 show that the electrolyte of the battery cell includes the first additive described in the embodiments of this application, and the content of the first additive meets the range given in the embodiments of this application, which can effectively improve the cycle performance of the battery. When the electrolyte also includes the second additive described in the embodiments of this application, it can further suppress the increase of the battery's internal resistance, thereby further improving the battery's cycle performance.

[0248] In contrast, the electrolyte of Comparative Example 1 does not contain the first additive, and its battery cycle performance is far inferior to that of Examples 1-23. In the electrolytes of Comparative Examples 2 and 3, the amount of the first additive added does not meet the range given in the embodiments of this application, and the cycle performance of their batteries is also not ideal.

[0249] It should be noted that this application is not limited to the above-described embodiments. The above embodiments are merely examples, and any embodiments with the same structure and effect as the technical concept within the scope of this application are included in the technical scope of this application. Furthermore, various modifications that can be conceived by those skilled in the art to the embodiments, and other ways of constructing by combining some of the constituent elements of the embodiments, without departing from the spirit of this application, are also included in the scope of this application.

Claims

1. A battery cell, characterized in that, The battery cell includes a positive electrode active material, a negative electrode active material, and an electrolyte, wherein the positive electrode active material includes a nickel-cobalt-manganese ternary material. The negative electrode active material includes silicon material, and the mass fraction of the silicon material in the negative electrode active material is s%% The electrolyte includes a first additive, which includes a halogen-containing cyclic ester compound. The mass fraction of the first additive in the electrolyte is P1%, and P1 satisfies the following relationships: 1≤P1≤0.8×s-0.12, 1.4≤s≤50.

2. The battery cell according to claim 1, characterized in that, The mass fraction s% of silicon material in the negative electrode active material satisfies: 1.4 ≤ s ≤ 25.

3. The battery cell according to claim 1 or 2, characterized in that, The first additive includes at least one of the compounds shown in Formula I: （Ⅰ） p represents 1, 2, or 3; R 11 Represents oxygen atom or C(Y) 1 )2, Y 1 Each of the following is independently represented: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, an alkenylyl group having 2 to 20 carbon atoms, an arylyl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenylyl group having 2 to 20 carbon atoms, a haloalkynylyl group having 2 to 20 carbon atoms, and a haloarylylyl group having 6 to 20 carbon atoms. R 12 R 13 R 14 R 15 Each independently includes one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloalkoxy group having 2 to 20 carbon atoms, a haloalkyneoxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms, and R 12 R 13 R 14 R 15 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms.

4. The battery cell according to claim 3, wherein, The compound represented by Formula I satisfies at least one of the following conditions (1) to (6): (1) p represents 1 or 2; (2) R 11 Represents oxygen atom or C(Y) 1 )2, Y 1 Each of the following can be independently represented: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, and propoxy. (3) R 12 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy; (4) R 13 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy; (5) R 14 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy; (6) R 15 Independently represents one of the following: hydrogen atom, fluorine atom, methyl, ethyl, propyl, fluoromethyl, fluoroethyl, fluoropropyl, methoxy, ethoxy, propoxy.

5. The battery cell according to claim 1, wherein, The first additive includes at least one of the following compounds: H1： H2： H3： H4： H5： H6： 。 6. The battery cell according to claim 1, characterized in that, The electrolyte also includes a second additive, which includes one or more boron-containing cyclic compounds.

7. The battery cell according to claim 6, characterized in that, The second additive includes at least one of the compounds shown in Formula II-1 and Formula II-2: (II-1) (II-2) R 21 R 22 Each independently includes one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloalkoxy group having 2 to 20 carbon atoms, a haloalkyneoxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms, and R 21 R 22 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms; R 23 R 24 Each can independently represent a carbonyl group C=O or C(Y) 2 )2, Y 2 Each independently comprises one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, or a haloalkyl group having 1 to 3 carbon atoms, and R 23 R 24 They do not both represent carbonyl C=O; R 25 R 26 Each independently includes one of the following: a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, an aryl group having 6 to 20 carbon atoms, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloalkoxy group having 2 to 20 carbon atoms, a haloalkyneoxy group having 2 to 20 carbon atoms, an aryloxy group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms, and R 25 R 26 At least one of the following includes a halogen atom, a haloalkyl group having 1 to 20 carbon atoms, a haloalkenyl group having 2 to 20 carbon atoms, a haloalkynyl group having 2 to 20 carbon atoms, a haloaryl group having 6 to 20 carbon atoms, a haloalkoxy group having 1 to 20 carbon atoms, a haloalkenoxy group having 2 to 20 carbon atoms, a haloalkynoxy group having 2 to 20 carbon atoms, and a haloaryloxy group having 6 to 20 carbon atoms; R 27 R 28 Each of the following is independently included: a hydrogen atom, a halogen atom, an alkyl group having 1 to 3 carbon atoms, or a haloalkyl group having 1 to 3 carbon atoms.

8. The battery cell according to claim 7, characterized in that, The compound represented by formula II-1 satisfies at least one of the following conditions (1) to (4): (1) R 21 It represents one of the following: hydrogen atom, methyl group, ethyl group, or fluoromethyl group; (2) R 22 It represents one of the following: hydrogen atom, methyl group, ethyl group, or fluoromethyl group; (3) R 23 It represents one of the following: hydrogen atom, methyl group, ethyl group, or carbonyl group; (4) R 24 It represents one of the following: hydrogen atom, methyl group, ethyl group, or carbonyl group; and / or The compound represented by formula II-2 satisfies at least one of the following conditions (5) to (8): (5) R 25 It represents one of the following: hydrogen atom, methyl group, ethyl group, or fluoromethyl group; (6) R 26 It represents one of the following: hydrogen atom, methyl group, ethyl group, or fluoromethyl group; (7) R 27 It represents one of the hydrogen atom, methyl group, and ethyl group; (8) R 28 It represents one of the following: hydrogen atom, methyl group, or ethyl group.

9. The battery cell according to claim 6, wherein, The second additive includes at least one of the following compounds: J1: J2: J3: J4: 。 10. The battery cell according to claim 6, characterized in that, The second additive has a mass content of P2% in the electrolyte, and P2 satisfies the relationship: 0.11 + 0.01 × t ≤ P2 ≤ 1.2, where t% is the mass percentage content of the nickel-cobalt-manganese ternary material in the positive electrode film of the battery cell.

11. The battery cell according to claim 10, characterized in that, The mass content of the second additive in the electrolyte is in a ratio of 1:40 to 1:1 to the mass content of the first additive in the electrolyte.

12. The battery cell according to claim 10, characterized in that, The mass content of the second additive in the electrolyte is in the ratio of the mass content of the first additive in the electrolyte to 1:5 to 1:

2.

13. The battery cell according to claim 1, characterized in that, The charging cutoff voltage of the battery cell is greater than or equal to 4.2V.

14. The battery cell according to claim 1, characterized in that, The charging cutoff voltage of the battery cell is greater than or equal to 4.3V.

15. The battery cell according to claim 1, characterized in that, In the nickel-cobalt-manganese ternary material, the molar content of Ni element among the transition metal elements is less than or equal to 0.

7.

16. The battery cell according to claim 1, characterized in that, The positive electrode active material includes a first nickel-cobalt-manganese ternary material in which the molar content of Ni in the transition metal elements is 0.5 or more.

17. The battery cell according to claim 16, characterized in that, The positive electrode active material also includes a second nickel-cobalt-manganese ternary material in which the molar content of Ni in the transition metal elements is less than 0.

5.

18. The battery cell according to claim 16, characterized in that, The positive electrode active material also includes lithium-rich manganese-based positive electrode material.

19. The battery cell according to claim 16, characterized in that, The positive electrode active material also includes lithium phosphate-containing positive electrode materials.

20. The battery cell according to claim 1, characterized in that, The silicon material includes at least one of nano-silicon, silicon oxide, and silicon carbide; and / or The negative electrode active material also includes carbon materials, which include at least one of artificial graphite, natural graphite, and hard carbon.

21. The battery cell according to claim 1, characterized in that, The volumetric particle size Dv50 of the silicon material is 3μm~20μm.

22. The battery cell according to claim 1, characterized in that, The volumetric particle size Dv50 of the silicon material is 3μm~15μm.

23. The battery cell according to claim 1, characterized in that, The electrolyte also includes cyclic carbonates.

24. The battery cell according to claim 1, characterized in that, At 25°C, the conductivity of the electrolyte is 7 ms / cm ~ 11 ms / cm.

25. The battery cell according to claim 1, characterized in that, At 25°C, the conductivity of the electrolyte is 8 ms / cm ~ 9 ms / cm.

26. The battery cell according to claim 1, characterized in that, At 25°C, the viscosity of the electrolyte is 2.5 mPa·s to 5 mPa·s.

27. The battery cell according to claim 1, characterized in that, At 25°C, the viscosity of the electrolyte is 3 mPa·s to 4 mPa·s.

28. A battery, characterized in that, The battery comprises a battery cell according to any one of claims 1-27.

29. An electrical appliance, characterized in that, The electrical device includes a battery cell according to any one of claims 1-27 or a battery according to claim 28.

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