Metal battery, battery device, and electric device

Abstract

The metal battery cell, the battery device and the electric device provided by the present disclosure have good high-temperature cycle performance and high-temperature storage performance.

Description

Technical Field

[0001] This disclosure relates to a metal battery cell, a battery device, and an electrical device. Background Technology

[0002] Lithium-ion battery cells have been widely used in consumer electronics, electric vehicles, and energy storage technologies, but their energy density is approaching its theoretical limit. To meet the higher energy density demands of future high-range electric vehicles and electric aircraft, it is necessary to develop metal battery cells using lithium metal anodes. Lithium metal possesses a high theoretical specific capacity (3860 mAh / g) and a low redox potential (-3.04 V vs. standard hydrogen electrode), making metal battery cells one of the most promising next-generation battery systems. However, the performance of metal battery cells needs further improvement. Summary of the Invention

[0003] This disclosure provides a metal battery cell, a battery device, and an electrical device. The metal battery cell has good high-temperature cycle performance and high-temperature storage performance.

[0004] In a first aspect, this disclosure provides a metal battery cell, including an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator located between the positive and negative electrode. The electrolyte includes an organic solvent, an electrolyte salt, a diluent, and a boron-based additive. The boron-based additive is an organic compound centered on boron and contains at least one of F atoms, B-O bonds, and B-B bonds. The charge / discharge temperature of the metal battery cell is 40°C-70°C.

[0005] The charge / discharge temperature of the metal battery cell disclosed herein is 40℃-70℃. Increasing the operating temperature of the metal battery cell is beneficial for improving lithium metal deposition at the negative electrode and reducing negative electrode volume expansion. Less negative electrode volume expansion results in higher stability of the negative electrode interface film and less electrolyte consumption. The electrolyte of the metal battery cell disclosed herein includes boron-based additives, which are boron-centered organic compounds containing at least one of F atoms, B-O bonds, and B-B bonds. The boron-based additives disclosed herein exhibit good compatibility with lithium metal. The boron-based additives disclosed herein can form an interfacial film at the positive electrode, reducing the surface activity of the delithiated positive electrode active material, improving the stability of the positive electrode / electrolyte interface, and reducing side reactions at the positive electrode / electrolyte interface. This stabilizes the structure of the delithiated positive electrode active material, reduces the dissolution of transition metal ions, and decreases the high-temperature gas production of the metal battery cell. The boron-based additives of this disclosure possess electron-deficient centers, allowing them to combine with electrolyte salt anions and F, thereby stabilizing anions in the electrolyte, reducing electrolyte acidity, and minimizing the impact of acidic substances on the stability of the electrolyte and the positive electrode active material. Furthermore, boron atoms can form B-F and B-O bonds with LiF, Li₂O, and Li₂O₂ in the positive and negative electrode interfacial film, thereby providing the interfacial film with good ion transport kinetics and resulting in lower interfacial impedance for both the positive and negative electrodes, thus reducing the polarization of the metal battery cell. Therefore, by adjusting the composition of the electrolyte and the charge / discharge temperature of the metal battery cell, this disclosure can stabilize the positive electrode and lithium metal negative electrode, reduce the high-temperature gas production of the metal battery cell, and enable the metal battery cell to exhibit good high-temperature cycle performance and high-temperature storage performance.

[0006] In some embodiments, the boron-based additive includes at least one of the following compounds.

[0007]

[0008] p and q independently represent integers from 0 to 6, R 1 Each independently represents F, C1-C3 alkyl, or C1-C3 fluoroalkyl, R 2 Each can be independently represented as F, C1-C3 alkyl, or C1-C3 fluoroalkyl.

[0009] m and n independently represent integers from 0 to 4, R 3 Each independently represents F, C1-C3 alkyl, or C1-C3 fluoroalkyl, R 4 Each can be independently represented as F, C1-C3 alkyl, or C1-C3 fluoroalkyl.

[0010] R 5 R 6 R 7Each of the following can be independently represented as C1-C3 alkyl, C1-C3 fluoroalkyl, C1-C3 alkoxy, C1-C3 fluoroalkoxy, phenyl, fluorophenyl, methylphenyl or fluoromethylphenyl.

[0011] s represents an integer from 1 to 5, R 8 Each of these groups independently represents F, C1-C3 alkyl, C1-C3 fluoroalkyl, cyano, or carboxyl, and R... 8 At least one of them represents a cyano or a carboxyl group.

[0012] R 9 R 10 R 11 Each of these can independently represent a C1-C3 alkyl, a C1-C3 fluoroalkyl, a phenyl, a fluorophenyl, a methylphenyl, or a fluoromethylphenyl, and R 9 R 10 R 11 At least one of them represents a C1-C3 fluoroalkyl, fluorophenyl, or fluoromethylphenyl.

[0013] R 12 R 13 R 14 Each of these can independently represent phenyl, fluorophenyl, methylphenyl, or fluoromethylphenyl, and R 12 R 13 R 14 At least one of them represents fluorophenyl or fluoromethylphenyl.

[0014] The use of the aforementioned boron-based additives helps reduce the dissolution of transition metal ions and the high-temperature gas production of metal battery cells, thereby further improving the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0015] In some embodiments, the boron-based additives include at least one of the compounds of Formula 1 and Formula 2. By including at least one of the compounds of Formula 1 and Formula 2 in the boron-based additives, the dissolution of transition metal ions can be further reduced, the high-temperature gas production of the metal battery cell can be reduced, and the high-temperature cycle performance and high-temperature storage performance of the metal battery cell can be improved.

[0016] In some embodiments, the boron-based additive includes at least one of the compounds of formula 1, formula 2, and formula 3. By including at least one of the compounds of formula 1, formula 2, and formula 3 in the boron-based additive, the dissolution of transition metal ions can be further reduced, the high-temperature gas production of the metal battery cell can be reduced, and the high-temperature cycle performance and high-temperature storage performance of the metal battery cell can be improved.

[0017] In some embodiments, p and q independently represent integers from 1 to 4.

[0018] In some embodiments, R 1 Each can be independently represented as either F or C1-C3 fluoroalkyl.

[0019] In some embodiments, R 2 Each can be independently represented as either F or C1-C3 fluoroalkyl.

[0020] In some embodiments, m and n independently represent integers from 1 to 4.

[0021] In some embodiments, R 3 Each can be independently represented as either F or C1-C3 fluoroalkyl.

[0022] In some embodiments, R 4 Each can be independently represented as either F or C1-C3 fluoroalkyl.

[0023] In some embodiments, R 5 R 6 R 7 Each can be independently represented as a C1-C3 fluoroalkyl, C1-C3 fluoroalkoxy, fluorophenyl, or fluoromethylphenyl.

[0024] In some embodiments, R 5 R 6 R 7 same.

[0025] In some embodiments, s represents an integer from 1 to 3.

[0026] In some embodiments, R 9 R 10 R 11 Each can be independently represented as a C1-C3 fluoroalkyl, fluorophenyl, or fluoromethylphenyl.

[0027] In some embodiments, R 9 R 10 R 11 same.

[0028] In some embodiments, R 12 R 13 R 14 They can be used independently to represent fluorophenyl or fluoromethylphenyl.

[0029] In some embodiments, R 12 R 13 R 14 same.

[0030] In some embodiments, the boron-based additive includes at least one of the following compounds.

[0031]

[0032]

[0033]

[0034]

[0035]

[0036]

[0037] In some embodiments, the boron-based additives constitute 0.1%-1% of the electrolyte by mass. Within this range, the boron-based additives can form a better-performing interfacial film without affecting the electrolyte viscosity, thereby further improving the high-temperature cycle performance and high-temperature storage performance of the metal battery cells.

[0038] In some embodiments, the electrolyte further includes a silicon-containing acid-removing additive. This additive can reduce the acidity of the electrolyte, minimizing the impact of acidic substances on the stability of the interfacial film and the positive electrode active material.

[0039] In some embodiments, the silicon-containing acid-removing additive includes one or more of tris(trimethylsilane) phosphate, silazane, N-trimethylsilylimidazolium, and tris(trimethylsilane)borate. These silicon-containing acid-removing additives can reduce the acidity of the electrolyte and also participate in the formation of the positive and negative electrode interface films.

[0040] In some embodiments, the mass percentage of the silicon-containing acid-removing additive in the electrolyte is 0.01%-0.5%. When the mass percentage of the silicon-containing acid-removing additive is within the above range, it can reduce the acidity of the electrolyte while forming an interface film with low impedance at the positive and negative electrodes.

[0041] In some embodiments, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate.

[0042] Optionally, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide.

[0043] In some embodiments, the organic solvent includes ether compounds.

[0044] Optionally, the organic solvent includes one or more of methyl n-butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, 1,2-dimethoxypropane, 1,3-dimethoxypropane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

[0045] In some embodiments, the diluent includes one or more of fluoroether diluents, aromatic diluents, and fluoroaromatic diluents.

[0046] Optionally, the diluent includes 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl, 1-(1,1,2,2-tetrafluoroethoxy)propane, 1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, 2,2, One or more of the following: 3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ester, bis-(1,2,2,2-tetrafluoroethyl) ether, 1,1,2,3,3,3-pentafluoropropyl difluoromethyl ether, 1,1,2,3,3,3-pentafluoropropyl-2,2,2-trifluoroethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, benzene, 3-fluorobenzene, m-difluorobenzene, 1,3,5-trifluorobenzene, and anisole.

[0047] In some embodiments, the molar ratio of electrolyte salt, organic solvent and diluent is 1:(0.8-3):(0.5-5).

[0048] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a lithium transition metal oxide. The lithium transition metal oxide includes Ni, and the molar percentage of Ni in the transition metal elements of the lithium transition metal oxide is more than 80%. This helps to improve the energy density of the metal battery cell.

[0049] In some embodiments, the volume distribution particle size Dv50 of the positive electrode active material is 2μm-12μm.

[0050] In some embodiments, the positive electrode active material comprises a single-crystal lithium transition metal oxide, and the area of ​​the single-crystal lithium transition metal oxide is 20%-100% of the total area of ​​the positive electrode active material. The single-crystal lithium transition metal oxide has no grain boundaries or contains only a small number of grain boundaries, making it less prone to particle breakage during charge-discharge cycles. It exhibits higher structural stability and particle integrity, enabling the metal battery cell to have better high-temperature cycle performance and high-temperature storage performance.

[0051] In some embodiments, the porosity of the positive electrode film is 13%-26%. High porosity results in good electrolyte wettability, thereby improving the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0052] In some embodiments, the negative electrode sheet includes a negative current collector and a lithium metal layer located on at least one side of the negative current collector. The lithium metal layer includes elemental lithium metal or an alloy formed by lithium metal and other metal elements and / or non-metal elements. Alternatively, the negative electrode sheet includes a negative current collector but does not include a lithium metal layer.

[0053] In a second aspect, this disclosure provides a battery device comprising a plurality of metal battery cells as described in the first aspect.

[0054] Thirdly, this disclosure provides an electrical device that includes a metal battery cell (as described in the first aspect) or a battery device (as described in the second aspect). Attached Figure Description

[0055] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the accompanying drawings used in the embodiments of this disclosure will be briefly described below. Obviously, the drawings described below are merely some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on the drawings without any creative effort.

[0056] Figure 1 A schematic diagram of a metal battery cell provided in some embodiments of this disclosure is shown.

[0057] Figure 2 A schematic diagram of an electrical device provided in some embodiments of this disclosure is shown.

[0058] The accompanying drawings are not necessarily drawn to scale. Detailed Implementation

[0059] The following detailed description, with appropriate reference to the accompanying drawings, specifically discloses embodiments of the metal battery cell, battery device, and power-consuming device of this disclosure. 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 to enable those skilled in the art to fully understand this disclosure and are not intended to limit the subject matter of the claims.

[0060] The "range" disclosed in this disclosure is defined by a lower limit and an upper limit, whereby a given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the 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 expected. Furthermore, if minimum range values ​​1 and 2 are listed, and if maximum range values ​​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 disclosure, 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.

[0061] Unless otherwise specified, all embodiments and optional embodiments of this disclosure may be combined with each other to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0062] Unless otherwise specified, all technical features and optional technical features of this disclosure can be combined to form new technical solutions, and such technical solutions should be considered as included in the disclosure of this disclosure.

[0063] Unless otherwise specified, all steps in this disclosure 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.

[0064] Unless otherwise specified, in this disclosure, the terms "first," "second," etc., are used to distinguish different objects, rather than to describe a specific order or primary / secondary relationship.

[0065] In this disclosure, the terms "multiple" or "a variety" refer to two or more kinds.

[0066] In the description of the embodiments of this disclosure, unless otherwise specified, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0067] In this disclosure, 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, n-propyl, and isopropyl. For example, C1-C3 alkyl groups, i.e., alkyl groups, may contain 1 to 3 carbon atoms.

[0068] In this disclosure, the term "alkoxy group" refers to a saturated hydrocarbon group containing an oxygen atom, including both straight-chain and branched structures. Examples of alkoxy groups include, but are not limited to, methoxy, ethoxy, and propoxy groups. For example, C1-C3 alkoxy groups, i.e., alkoxy groups, may contain 1 to 3 carbon atoms.

[0069] In this disclosure, a "fluorinated" group refers to a group obtained by replacing at least one hydrogen atom in a group with an F atom. A fluorinated group can be a partially fluorinated group or a fully fluorinated group.

[0070] Throughout this specification, substituents of compounds are disclosed by groups or ranges. It is expressly intended that such description include each individual subcombination of members of these groups and ranges. For example, it is expressly intended that the term "C1-C3 alkyl" individually discloses C1, C2, C3, C1-C3, C1-C2, and C2-C3 alkyl groups.

[0071] Unless otherwise stated, the test temperature for all parameters mentioned in this disclosure is 25°C.

[0072] The metal battery cells mentioned in the embodiments of this disclosure are capable of charging and discharging independently. The metal battery cells may be cylindrical, cuboid, or other shapes, and this disclosure does not limit this. Figure 1 The example is a rectangular metal battery cell 5.

[0073] The battery apparatus mentioned in the embodiments of this disclosure may include one or more metal battery cell assemblies for providing voltage and capacity. The metal battery cell assembly may include multiple metal battery cells, which are connected in series, parallel, or mixed connections via busbars.

[0074] In some embodiments, a metal battery cell assembly is typically formed by arranging multiple metal battery cells.

[0075] As an example, a metal battery cell assembly can be a battery module, which is formed by arranging and fixing multiple metal battery cells together to form an independent module. As another example, a battery module can be formed by bundling multiple metal battery cells together with cable ties.

[0076] In some embodiments, the battery device may be a battery pack, which includes a housing and one or more metal battery cell assemblies housed within the housing.

[0077] As an example, the metal battery cell assembly can be a battery module, which can be housed in a housing by fixing the battery module in the housing.

[0078] As an example, metal battery cell assemblies can also be housed in a housing by directly fixing multiple metal battery cells to the housing.

[0079] As an example, the enclosure may include a first enclosure and a second enclosure. The first enclosure and the second enclosure are fastened together to form a closed space inside the enclosure to house the metal battery cell assembly. Here, "closed" refers to covering or closing, which can be either sealed or unsealed. The first enclosure may be a top cover or a bottom plate.

[0080] As an example, the enclosure may include a top cover, a frame, and a bottom plate. The top cover and bottom plate are connected to the frame, creating an enclosed space inside the enclosure to house the individual metal battery cells.

[0081] In some embodiments, the housing may be part of the vehicle's chassis structure. For example, a portion of the housing may be at least a part of the vehicle's floor, or a portion of the housing may be at least a part of the vehicle's crossbeams and longitudinal beams.

[0082] The technical solutions described in this disclosure are applicable to various electrical devices that use metal battery cells or battery devices, such as, but not limited to, mobile devices (e.g., mobile phones, tablets, 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 aircraft, electric trains, ships and satellites, energy storage systems, etc. Metal battery cells and battery devices are used to store or provide electrical energy.

[0083] Figure 2 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, etc.

[0084] The metal battery cells provided in this disclosure can be lithium metal battery cells, negative electrode-free lithium metal battery cells, etc. Negative electrode-free lithium metal battery cells typically refer to lithium metal battery cells in which a negative electrode active material layer is not actively formed on the negative electrode side during the manufacturing process. For example, during the manufacturing process, a negative electrode active material layer formed from carbonaceous materials is not formed at the negative electrode through processes such as coating or deposition. During the first charge, lithium ions gain electrons on the negative electrode side and deposit on the surface of the negative electrode current collector to form lithium metal. During discharge, the lithium metal can be converted back into lithium ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other lithium metal battery cells, negative electrode-free lithium metal battery cells can achieve higher energy density because they lack a negative electrode active material layer. In some embodiments, to improve the performance of the battery cell, some conventional materials that can be used as negative electrode active materials, such as carbon materials, can also be provided on the negative electrode side of the negative electrode-free lithium metal battery cell. Although these materials possess a certain capacity, their content is low, and they are not used as the primary negative electrode active material in the battery cell. Therefore, a battery cell constructed in this way can still be considered a negative electrode-free lithium metal battery cell. The CB (Cell Balance) value of a negative electrode-free lithium metal battery cell is typically very small; for example, in some embodiments, the CB value of a negative electrode-free lithium metal battery cell can be less than or equal to 0.1. The CB value is the area capacity per unit area of ​​the negative electrode divided by the area capacity per unit area of ​​the positive electrode in the battery cell. Because a negative electrode-free lithium metal battery cell contains no or only a small amount of negative electrode active material, the area capacity per unit area of ​​the negative electrode is small, and consequently, the CB value is very small, typically less than or equal to 0.1.

[0085] High energy density and long lifespan are common goals for metal battery cells. Increasing electrolyte concentration is one of the effective means to improve the lifespan of metal battery cells. Currently, locally concentrated high-concentration electrolytes (LHCE) are often used to match lithium metal anodes. This electrolyte can form a relatively dense interfacial film at the anode, reducing side reactions at the anode / electrolyte interface; this electrolyte also has good oxidation-reduction resistance due to its unique solvation structure. However, during the charge-discharge process of a metal battery cell, the continuous damage and regeneration of the anode interfacial film mainly consumes electrolyte salts rather than organic solvents. At room temperature, the anode of a metal battery cell suffers from severe infinite volume expansion during cyclic charge-discharge. This volume expansion leads to continuous damage and regeneration of the anode interfacial film, continuously consuming electrolyte and active lithium. At the same time, the anode interfacial film also thickens, which can increase the polarization of the battery cell. In addition, lithium metal is highly reactive and readily undergoes chemical and electrochemical reactions with the electrolyte. Therefore, during the charging and discharging process of a metal battery cell, the negative electrode expands significantly, resulting in greater consumption of electrolyte and active lithium. This leads to a rapid decrease in electrolyte concentration, which in turn affects the performance of the metal battery cell.

[0086] Based on this, the present disclosure provides a metal battery cell and a battery device and an electrical device containing the same. By adjusting the composition of the electrolyte and the charging and discharging temperature of the metal battery cell, the positive electrode and the lithium metal negative electrode can be stabilized, the high-temperature gas production of the metal battery cell can be reduced, and the metal battery cell can have good high-temperature cycle performance and high-temperature storage performance.

[0087] The metal battery cell provided in this disclosure includes an electrode assembly and an electrolyte. The electrode assembly includes a positive electrode, a negative electrode, and a separator, with the separator located between the positive and negative electrodes. The electrolyte includes an organic solvent, an electrolyte salt, a diluent, and a boron-based additive. The boron-based additive is an organic compound centered on boron and contains at least one of F atoms, B-O bonds, and B-B bonds. The charge / discharge temperature of the metal battery cell is 40°C-70°C.

[0088] The charge / discharge temperature of the metal battery cell disclosed herein is 40℃-70℃. The charge / discharge temperature of the metal battery cell refers to its actual operating temperature. Increasing the operating temperature of the metal battery cell is beneficial for improving lithium metal deposition on the negative electrode and reducing negative electrode volume expansion. Less negative electrode volume expansion results in higher stability of the negative electrode interface film and less electrolyte consumption. In some embodiments, a heating module can be provided on the outside of the metal battery cell to regulate its charge / discharge temperature.

[0089] However, at high charge and discharge temperatures, the structural stability of delithiated cathode active materials, especially high-nickel cathode active materials, deteriorates, making them prone to oxygen release. Furthermore, the high surface activity of delithiated cathode active materials makes them susceptible to side reactions with the electrolyte, leading to increased gas production in the metal battery cells. Conventional electrolyte additives, such as 1,3-propenesulfonate lactone, tripropynyl phosphate, vinyl sulfite, and 2-fluoropyridine, suffer from high film-forming impedance and poor compatibility with lithium metal, thus hindering the improvement of metal battery cell lifespan.

[0090] The electrolyte of the metal battery cell disclosed herein includes boron-based additives, which are boron-centered organic compounds containing at least one of F atoms, B-O bonds, and B-B bonds. The boron-based additives disclosed herein exhibit good compatibility with lithium metal. The boron-based additives disclosed herein can form an interfacial film at the positive electrode, reducing the surface activity of the delithiated positive electrode active material, improving the stability of the positive electrode / electrolyte interface, and reducing side reactions at the positive electrode / electrolyte interface. This stabilizes the structure of the delithiated positive electrode active material, reduces the dissolution of transition metal ions, and reduces the high-temperature gas production of the metal battery cell. The boron-based additives disclosed herein have electron-deficient centers that can combine with electrolyte salt anions and F, thereby stabilizing anions in the electrolyte, reducing electrolyte acidity, and reducing the impact of acidic substances on the stability of the electrolyte and the positive electrode active material. B atoms can also form B-F bonds and B-O bonds with LiF, Li2O, Li2O2, etc. in the positive and negative electrode interfacial film, thereby giving the interfacial film good ion transport kinetics and giving the positive and negative electrodes low interfacial impedance, thus reducing the polarization of the metal battery cell.

[0091] Therefore, by adjusting the composition of the electrolyte and the charging and discharging temperature of the metal battery cell, this disclosure can stabilize the positive electrode and the lithium metal negative electrode, reduce the high-temperature gas production of the metal battery cell, and enable the metal battery cell to have good high-temperature cycle performance and high-temperature storage performance.

[0092] In some embodiments, boron-based additives contain B-B bonds.

[0093] B-B bonds are easier to break to form a thin and uniform cathode interface film. Furthermore, the cathode interface film exhibits a certain degree of nucleophilicity after being attacked by O. This can further reduce the surface activity of the delithiated cathode active material, improve the stability of the cathode / electrolyte interface, and reduce side reactions at the cathode / electrolyte interface. Consequently, it can stabilize the structure of the delithiated cathode active material, reduce the dissolution of transition metal ions, and reduce the high-temperature gas production of metal battery cells.

[0094] Optionally, boron-based additives contain B-B bonds and also contain F atoms.

[0095] F atoms help improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cell, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0096] In some embodiments, the boron-based additives contain a boron-oxygen six-membered heterocycle and a benzene ring.

[0097] The boron-oxygen six-membered heterocycle can open the ring, giving the interfacial film good flexibility, while the benzene ring can also give the interfacial film mechanical rigidity, thus helping to further reduce the high-temperature gas production of metal battery cells and improve the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0098] Optionally, the boron-based additives contain a boron-oxygen six-membered heterocycle and a benzene ring, and the boron-based additives also contain F atoms.

[0099] F atoms help improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cell, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0100] In some embodiments, the boron-based additive includes at least one of the following compounds.

[0101]

[0102] p and q independently represent integers from 0 to 6, R 1 Each independently represents F, C1-C3 alkyl, or C1-C3 fluoroalkyl, R 2 Each can be independently represented as F, C1-C3 alkyl, or C1-C3 fluoroalkyl.

[0103] m and n independently represent integers from 0 to 4, R 3 Each independently represents F, C1-C3 alkyl, or C1-C3 fluoroalkyl, R 4 Each can be independently represented as F, C1-C3 alkyl, or C1-C3 fluoroalkyl.

[0104] R 5 R 6 R 7 Each of the following can be independently represented as C1-C3 alkyl, C1-C3 fluoroalkyl, C1-C3 alkoxy, C1-C3 fluoroalkoxy, phenyl, fluorophenyl, methylphenyl or fluoromethylphenyl.

[0105] s represents an integer from 1 to 5, R 8 Each of these groups independently represents F, C1-C3 alkyl, C1-C3 fluoroalkyl, cyano, or carboxyl, and R... 8 At least one of them represents a cyano or a carboxyl group.

[0106] R9 R 10 R 11 Each of these can independently represent a C1-C3 alkyl, a C1-C3 fluoroalkyl, a phenyl, a fluorophenyl, a methylphenyl, or a fluoromethylphenyl, and R 9 R 10 R 11 At least one of them represents a C1-C3 fluoroalkyl, fluorophenyl, or fluoromethylphenyl.

[0107] R 12 R 13 R 14 Each of these can independently represent phenyl, fluorophenyl, methylphenyl, or fluoromethylphenyl, and R 12 R 13 R 14 At least one of them represents fluorophenyl or fluoromethylphenyl.

[0108] The use of the aforementioned boron-based additives helps reduce the dissolution of transition metal ions and the high-temperature gas production of metal battery cells, thereby further improving the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0109] The representation of a single key passing through a single ring means that the single key can be connected to any accessible position on the single ring.

[0110] When p and q are 0, it means that the hydrogen atoms on the ring have not been substituted.

[0111] When m and n are 0, it means that the hydrogen atoms on the ring have not been substituted.

[0112] Optionally, p and q can each independently represent an integer from 1 to 4. More alternatively, p and q can each independently represent an integer from 2 to 4.

[0113] Optionally, R 1 Each can be independently represented as either F or C1-C3 fluoroalkyl. Alternatively, R... 1 Each can be used independently to represent either F or fluoromethyl.

[0114] Optionally, R 2 Each can be independently represented as either F or C1-C3 fluoroalkyl. Alternatively, R... 2 Each can be used independently to represent either F or fluoromethyl.

[0115] Replacing hydrogen atoms with F or C1-C3 fluoroalkyl groups helps to improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cells, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cells.

[0116] Optionally, m and n can each independently represent an integer from 1 to 4. More alternatively, m and n can each independently represent an integer from 2 to 4.

[0117] Optionally, R 3 Each can be independently represented as either F or C1-C3 fluoroalkyl. Alternatively, R... 3 Each can be used independently to represent either F or fluoromethyl.

[0118] Optionally, R 4 Each can be independently represented as either F or C1-C3 fluoroalkyl. Alternatively, R... 4 Each can be used independently to represent either F or fluoromethyl.

[0119] Replacing hydrogen atoms with F or C1-C3 fluoroalkyl groups helps to improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cells, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cells.

[0120] Optionally, R 5 R 6 R 7 Each can be independently represented as a C1-C3 fluoroalkyl, C1-C3 fluoroalkoxy, fluorophenyl, or fluoromethylphenyl.

[0121] Replacing hydrogen atoms with C1-C3 fluoroalkyl, C1-C3 fluoroalkoxy, fluorophenyl, or fluoromethylphenyl can help improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cell, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0122] Optionally, R 5 R 6 R 7 They can be used independently to represent fluorophenyl or fluoromethylphenyl.

[0123] The compound of Formula 3 contains a boron-oxygen six-membered heterocycle, which can be ring-opened, giving the interfacial film good flexibility. The benzene ring can also give the interfacial film mechanical rigidity, thereby helping to reduce the high-temperature gas production of metal battery cells and improve the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0124] Optionally, R 5 R 6 R 7 same.

[0125] Optionally, s represents an integer from 1 to 3.

[0126] Optionally, R 9 R 10 R 11Each can be independently represented as a C1-C3 fluoroalkyl, fluorophenyl, or fluoromethylphenyl.

[0127] Replacing hydrogen atoms with C1-C3 fluoroalkyl, fluorophenyl, or fluoromethylphenyl compounds helps improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cells, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cells.

[0128] Optionally, R 9 R 10 R 11 They can be used independently to represent fluorophenyl or fluoromethylphenyl.

[0129] Optionally, R 9 R 10 R 11 same.

[0130] Optionally, R 12 R 13 R 14 They can be used independently to represent fluorophenyl or fluoromethylphenyl.

[0131] Optionally, R 12 R 13 R 14 same.

[0132] In some embodiments, the boron-based additives include at least one of the compounds of Formula 1 and Formula 2.

[0133] Compounds of Formula 1 and Formula 2 contain both B-B and B-O bonds. The B-B bonds are more easily broken to form a thin and uniform cathode interface film. Furthermore, the cathode interface film exhibits nucleophilicity after being attacked by O, thereby further reducing the surface activity of the delithiated cathode active material, improving the cathode / electrolyte interface stability, and reducing side reactions at the cathode / electrolyte interface. This stabilizes the structure of the delithiated cathode active material, reduces transition metal ion dissolution, and decreases the high-temperature gas generation of the metal battery cell. Therefore, by including at least one of the boron-based additives from Formula 1 and Formula 2, the dissolution of transition metal ions can be further reduced, the high-temperature gas generation of the metal battery cell can be decreased, and the high-temperature cycle performance and high-temperature storage performance of the metal battery cell can be improved.

[0134] In some embodiments, the boron-based additives include at least one of the compounds of Formula 1 and Formula 2, where p and q independently represent integers from 1 to 4, and R 1 Each independently represents either F or C1-C3 fluoroalkyl, R 2 Each independently represents F or C1-C3 fluoroalkyl, m and n independently represent integers from 1 to 4, R 3Each independently represents either F or C1-C3 fluoroalkyl, R 4 Each can be independently represented as either F or C1-C3 fluoroalkyl.

[0135] Replacing hydrogen atoms with F or C1-C3 fluoroalkyl groups helps to improve the ion transport kinetics of the interfacial membrane, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cells, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cells.

[0136] Optionally, p and q can each independently represent integers from 2 to 4.

[0137] Optionally, R 1 Each can be used independently to represent either F or fluoromethyl.

[0138] Optionally, R 2 Each can be used independently to represent either F or fluoromethyl.

[0139] Optionally, m and n can represent integers from 2 to 4 independently.

[0140] Optionally, R 3 Each can be used independently to represent either F or fluoromethyl.

[0141] Optionally, R 4 Each can be used independently to represent either F or fluoromethyl.

[0142] In some embodiments, boron-based additives include at least one of the compounds of formula 1, formula 2, and formula 3.

[0143] Compounds of Formula 1 and Formula 2 contain both B-B and B-O bonds. The B-B bonds are more easily broken to form a thin and uniform cathode interface film. Furthermore, the cathode interface film exhibits nucleophilicity after being attacked by O, thereby further reducing the surface activity of the delithiated cathode active material, improving the stability of the cathode / electrolyte interface, and reducing side reactions at the cathode / electrolyte interface. This stabilizes the structure of the delithiated cathode active material, reduces transition metal ion dissolution, and decreases the high-temperature gas generation of the metal battery cell. Compound of Formula 3 contains a boron-oxygen six-membered heterocycle, which can undergo ring-opening, giving the interface film good flexibility. Therefore, by including at least one of Compounds 1 and 2, as well as Compound 3, boron-based additives can further reduce transition metal ion dissolution, decrease the high-temperature gas generation of the metal battery cell, and improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0144] In some embodiments, the boron-based additives include at least one of the compounds of formula 1 and formula 2, and a compound of formula 3, wherein p and q independently represent integers from 1 to 4, and R 1 Each independently represents either F or C1-C3 fluoroalkyl, R 2Each independently represents F or C1-C3 fluoroalkyl, m and n independently represent integers from 1 to 4, R 3 Each independently represents either F or C1-C3 fluoroalkyl, R 4 Each independently represents either F or C1-C3 fluoroalkyl, R 5 R 6 R 7 Each can be independently represented as a C1-C3 fluoroalkyl, C1-C3 fluoroalkoxy, fluorophenyl, or fluoromethylphenyl.

[0145] By further incorporating F atoms into compounds of formula 1, formula 2, and formula 3, it is helpful to improve the ion transport kinetics of the interfacial film, reduce the interfacial impedance of the positive and negative electrodes, reduce the polarization of the metal battery cell, and further improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0146] Optionally, p and q can each independently represent integers from 2 to 4.

[0147] Optionally, R 1 Each can be used independently to represent either F or fluoromethyl.

[0148] Optionally, R 2 Each can be used independently to represent either F or fluoromethyl.

[0149] Optionally, m and n can represent integers from 2 to 4 independently.

[0150] Optionally, R 3 Each can be used independently to represent either F or fluoromethyl.

[0151] Optionally, R 4 Each can be used independently to represent either F or fluoromethyl.

[0152] Optionally, R 5 R 6 R 7 They can be used independently to represent fluorophenyl or fluoromethylphenyl.

[0153] The compound of Formula 3 contains a boron-oxygen six-membered heterocycle, which can be ring-opened, giving the interfacial film good flexibility. The benzene ring can also give the interfacial film mechanical rigidity, thereby helping to further reduce the high-temperature gas production of metal battery cells and improve the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0154] Optionally, R 5 R 6 R 7 same.

[0155] In some embodiments, the boron-based additive includes at least one of the following compounds.

[0156]

[0157]

[0158]

[0159]

[0160]

[0161]

[0162] In some embodiments, the boron additives are present in the electrolyte at a mass ratio of 0.1% to 1%, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any range of the above values.

[0163] When the mass ratio of boron-based additives is within the above range, a better interfacial film can be formed without affecting the electrolyte viscosity, thereby further improving the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0164] Optionally, the boron-based additives account for 0.2%-0.6% of the mass of the electrolyte.

[0165] In some embodiments, the electrolyte may also include a silicon-containing acid-removing additive.

[0166] Silicon-containing acid-removing additives can capture protonated hydrogen in the electrolyte and react with acidic substances in the electrolyte, such as HF, thereby reducing the acidity of the electrolyte and minimizing the impact of acidic substances on the stability of the interfacial film and the positive electrode active material.

[0167] Optionally, the silicon-containing deacidifying additive includes one or more of tris(trimethylsilane) phosphate (TMSP), silazane, N-trimethylsilylimidazolium, and tris(trimethylsilane)borate.

[0168] The aforementioned silicon-containing acid-removing additives can reduce the acidity of the electrolyte and also participate in the formation of the positive and negative electrode interface films.

[0169] Optionally, the mass percentage of the silicon-containing acid-removing additive in the electrolyte is 0.01%-0.5%, for example, it can be 0.01%, 0.02%, 0.05%, 0.08%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, or any range of the above values.

[0170] When the mass ratio of silicon-containing acid-removing additives is within the above range, it can reduce the acidity of the electrolyte while forming an interface film with low impedance at the positive and negative electrodes.

[0171] The aforementioned mass percentages of boron-based additives and silicon-containing deacidifying additives refer to the mass percentages obtained by testing the free electrolyte after disassembling the metal battery cell.

[0172] The mass percentage of boron-based additives and silicon-containing acid-removing additives in the electrolyte of a metal battery cell can be obtained by the following method: After disassembling the metal battery cell, take a sample of the free electrolyte in the residual space. Separate the components such as organic solvents, diluents, boron-based additives, and silicon-containing acid-removing additives from the electrolyte salt components by gas chromatography. Then, the specific structure of each component can be confirmed by high-precision mass spectrometry and nuclear magnetic resonance spectroscopy. Finally, the content of each component is quantitatively analyzed by ion chromatography.

[0173] In the above tests, metal battery cells refer to fresh metal battery cells, such as metal battery cells that have been manufactured (e.g., those that have not been charged and discharged after formation) or metal battery cells that have been assembled on electrical devices and have fewer than 10 cycles.

[0174] In some embodiments, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium trifluoromethanesulfonate (LiOTF), lithium difluorophosphate (LiDFP), lithium dioxolaneborate (LiBOB), lithium difluorooxolaneborate (LiDFOB), lithium difluorodioxolane phosphate, and lithium tetrafluorooxolane phosphate.

[0175] Optionally, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide.

[0176] Lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide have a wide electrochemical window, high thermal stability and high ionic conductivity, which can provide less electrolyte high-pressure decomposition and faster ion transport rate.

[0177] Optionally, the electrolyte salt includes lithium bis(fluorosulfonyl)imide.

[0178] Fluorosulfonamide anion FSI - It has better compatibility with lithium metal and can form a better interface film on the surface of lithium metal, thereby further improving the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0179] In some embodiments, the organic solvent includes ether compounds.

[0180] Optionally, the organic solvent includes one or more of methyl n-butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, 1,2-dimethoxypropane, 1,3-dimethoxypropane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether.

[0181] The electrolyte disclosed herein is a locally high-concentration electrolyte. A locally high-concentration electrolyte is a high-concentration electrolyte with the addition of a diluent that is miscible with organic solvents but does not dissolve electrolyte salts or has extremely poor electrolyte salt dissolving ability. The addition of the diluent does not affect the unique solvation structure of the high-concentration electrolyte and can improve the viscosity and ionic conductivity of the electrolyte, thereby improving the electrolyte wettability of the electrode assembly.

[0182] In some embodiments, the diluent includes one or more of fluoroether diluents, aromatic diluents, and fluoroaromatic diluents.

[0183] Optionally, the diluent includes 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl, 1-(1,1,2,2-tetrafluoroethoxy)propane, 1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, 2,2, One or more of the following: 3,3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ester, bis-(1,2,2,2-tetrafluoroethyl) ether, 1,1,2,3,3,3-pentafluoropropyl difluoromethyl ether, 1,1,2,3,3,3-pentafluoropropyl-2,2,2-trifluoroethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, benzene, 3-fluorobenzene, m-difluorobenzene, 1,3,5-trifluorobenzene, and anisole.

[0184] In some embodiments, the molar ratio of electrolyte salt, organic solvent, and diluent is 1:(0.8-3):(0.5-5). This forms a locally high-concentration electrolyte, which can give the electrolyte a good solvation structure, good resistance to oxidation and reduction, and also give the electrolyte both high ionic conductivity and low viscosity, thereby improving the electrolyte wettability of the electrode assembly.

[0185] The molar ratio of electrolyte salt to organic solvent can be 1:(0.8-3), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, 1:2.1, 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3, or any range of the above values.

[0186] The molar ratio of electrolyte salt to diluent can be 1:(0.5-5), for example, it can be 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:3, 1:4.2, 1:4.4, 1:4.6, 1:4.8, 1:5, or any range of the above values.

[0187] The electrolyte can be prepared using methods known in the art.

[0188] The metal battery cell includes an electrode assembly, which can be a wound structure or a stacked structure, and the embodiments disclosed herein are not limited to this.

[0189] The number of electrode components contained in a metal battery cell can be one or more, and this disclosure does not limit this.

[0190] The electrode assembly includes a positive electrode, a negative electrode, and a separator, which will be described in detail below.

[0191] [Positive electrode plate]

[0192] In some embodiments, the positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The positive electrode film layer includes a positive active material, which includes a lithium transition metal oxide (LiMeO). The LiMeO includes Ni, and the molar percentage of Ni in the transition metal elements of the LiMeO is more than 80%. The positive current collector has two surfaces opposite 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.

[0193] Lithium transition metal oxides have a layered structure.

[0194] The positive electrode active material disclosed herein includes lithium transition metal oxides with high Ni content. Higher Ni content in lithium transition metal oxides results in higher theoretical specific capacity, thus contributing to improved energy density of metal battery cells. However, higher Ni content also leads to increased surface activity and structural instability of the delithiated positive electrode active material, making it more prone to structural collapse and oxygen release at high temperatures. This disclosure addresses this by including boron-based additives in the electrolyte, which can form an interfacial film at the positive electrode, reducing the surface activity of the delithiated positive electrode active material, improving the stability of the positive electrode / electrolyte interface, and reducing side reactions at the positive electrode / electrolyte interface. This stabilizes the structure of the delithiated positive electrode active material, reduces transition metal ion dissolution, decreases high-temperature gas generation in metal battery cells, and fully leverages the high specific capacity advantage of the positive electrode active material.

[0195] Optionally, the molar percentage of Ni in the transition metal elements of the lithium transition metal oxide is above 83%, above 84%, above 85%, above 86%, above 87%, or above 90%.

[0196] In some embodiments, the positive electrode active material may include Li a Ni b Co c M d O e D f The lithium transition metal oxide, 0.8≤a≤1.2, 0.8≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M can be one or more of Ge, Mo, Sn, Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and D can be one or more of N, F, S and Cl.

[0197] As an example, positive electrode active materials may include, but are not limited to, LiNi. 0.8 Co 0.1 Mn 0.1 O2(NCM811), LiNi 0.80 Co 0.15 Al 0.05 O2, LiNi 0.9 Co 0.05 Mn 0.05 O2(Ni90), LiNi 0.92 Co 0.04 Mn 0.04 O2(Ni92), LiNi 0.93 Co 0.035 Mn 0.035 O2(Ni93), LiNi 0.96 Co 0.02Mn 0.02 One or more of O2 (Ni96).

[0198] During the charging and discharging process, lithium (Li) is deintercalated and consumed in metal battery cells, resulting in varying molar Li content at different discharge states. In the examples of positive electrode active materials in this disclosure, the molar Li content represents the initial state of the material, i.e., the state before feeding. When the positive electrode active material is applied to a metal battery cell, the molar Li content changes after charge-discharge cycles. Similarly, in the examples of positive electrode active materials in this disclosure, the molar O content is only a theoretical value. Lattice oxygen release causes changes in the molar O content, and the actual molar O content will also fluctuate.

[0199] In some embodiments, the volume distribution particle size Dv50 of the positive electrode active material is 2μm-12μm, for example, it can be 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, or any range of the above values.

[0200] In some embodiments, the lithium transition metal oxide includes a single-crystal lithium transition metal oxide, and the area of ​​the single-crystal lithium transition metal oxide is 20%-100% of the total area of ​​the positive electrode active material, for example, it can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, 100%, or any range of the above values.

[0201] In some embodiments, the lithium transition metal oxide includes a single-crystal lithium transition metal oxide, and the area of ​​the single-crystal lithium transition metal oxide is 100% of the total area of ​​the positive electrode active material.

[0202] Lithium transition metal oxides with single-crystal morphology have no grain boundaries or contain only a small number of grain boundaries. They are less prone to particle breakage during cyclic charging and discharging, and have higher structural stability and particle integrity. This allows metal battery cells to have better high-temperature cycling performance and high-temperature storage performance.

[0203] In some embodiments, the lithium transition metal oxide includes single-crystal lithium transition metal oxide and polycrystalline lithium transition metal oxide, wherein the area of ​​single-crystal lithium transition metal oxide is 20%-99% of the total area of ​​the positive electrode active material, and the area of ​​polycrystalline lithium transition metal oxide is 1%-80% of the total area of ​​the positive electrode active material.

[0204] For example, the area of ​​a single-crystal lithium transition metal oxide can be 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 99%, or any combination of the above values, representing the total area of ​​the cathode active material.

[0205] For example, the area of ​​the polycrystalline lithium transition metal oxide can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or any combination of the above values, representing 1% of the total area of ​​the positive electrode active material.

[0206] The area ratio of single-crystal lithium transition metal oxides and the area ratio of polycrystalline lithium transition metal oxides in the positive electrode active material can be tested as follows: Using a scanning electron microscope (SEM) according to JY / T 010-1996, obtain SEM images of the positive electrode sheet. Randomly select a test sample (e.g., 50mm x 100mm). Randomly select multiple test areas (e.g., 5) in the test sample. At a certain magnification (e.g., 500x or more), calculate the sum of the areas of all single-crystal lithium transition metal oxides, the sum of the areas of all polycrystalline lithium transition metal oxides, and the sum of the areas of all positive electrode active materials in each test area. Obtain the area ratio of single-crystal lithium transition metal oxides and the area ratio of polycrystalline lithium transition metal oxides. Then, take the average value of the test results of multiple test areas as the area ratio of single-crystal lithium transition metal oxides and the area ratio of polycrystalline lithium transition metal oxides in the positive electrode active material. To ensure the accuracy of the test results, multiple test samples (e.g., 10) can be taken for the above test, and the average value of each test sample can be taken as the final test result. The testing instrument can be a ZEISS Sigma300.

[0207] Lithium transition metal oxides with single-crystal morphology have no grain boundaries or contain only a small number of grain boundaries. They are less prone to particle breakage during cyclic charging and discharging, and have higher structural stability and particle integrity. This allows metal battery cells to have better high-temperature cycling performance and high-temperature storage performance.

[0208] Polycrystalline lithium transition metal oxides exhibit higher electrochemical activity and higher specific capacity, which helps improve the rate performance and energy density of metal battery cells. By incorporating a small amount of polycrystalline lithium transition metal oxides into the cathode active material, metal battery cells can achieve good rate performance while maintaining good high-temperature cycling and high-temperature storage performance.

[0209] The average particle size of polycrystalline lithium transition metal oxides is larger than that of single-crystal lithium transition metal oxides. By including a small amount of polycrystalline lithium transition metal oxides in the positive electrode active material, it is also helpful to improve the energy density of the metal battery cell.

[0210] In some embodiments, the positive electrode film may further include a positive electrode conductive agent, which may include, but is not limited to, one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor-grown carbon fibers (VGCF).

[0211] In some embodiments, the positive electrode film layer may further include a positive electrode binder, which may include, but is not limited to, one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene-propylene terpolymer, ethylene-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resins.

[0212] In some embodiments, the porosity of the positive electrode film is 13%-26%, for example, it can be 13%, 13.5%, 14%, 14.5%, 15%, 15.5%, 16%, 16.5%, 17%, 17.5%, 18%, 18.5%, 19%, 19.5%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, or any range of the above values.

[0213] The high porosity and good electrolyte wettability of the positive electrode film can improve the high-temperature cycle performance and high-temperature storage performance of the metal battery cell.

[0214] The porosity of the positive electrode film can be tested as follows: After fully disassembling the metal battery cell, remove the positive electrode sheet. Immerse the positive electrode sheet in an organic solvent (e.g., dimethyl carbonate) for a period of time (e.g., 2-10 hours). Then, remove the positive electrode sheet and dry it at a certain temperature and time (e.g., 60°C for more than 4 hours). After drying, remove the positive electrode sheet. Take a single-sided coated positive electrode sheet (if it is a double-sided coated positive electrode sheet, wipe off the positive electrode film layer on one side first), and cut it into small circular samples of a certain area. Calculate the apparent volume V1 of the positive electrode sheet. Referring to GB / T 24586-2009, using an inert gas (such as helium or nitrogen) as a medium, use the gas displacement method and a true density meter to measure the true volume V2 of the positive electrode sheet. The porosity of the positive electrode film = (V1-V2) / V1×100%. Multiple samples (e.g., 30 pieces) with good appearance and no powder shedding at the edges can be tested, and the average value of the results should be taken, which can improve the accuracy of the test results. The testing instrument can be a Micromeritics AccuPyc II 1340 true density meter.

[0215] In some embodiments, the positive current collector can be a metal foil or a composite current collector. The metal foil can be a pure metal, an alloy, or a surface-treated metal. For example, the metal foil can be carbon-coated aluminum foil, aluminum foil, nickel foil, or titanium foil. The composite current collector can include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. For example, the metal material can be one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer substrate can be one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0216] 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 positive electrode active materials, positive electrode conductive agents, positive electrode binders, and any other components in a solvent and mixing them thoroughly. The solvent can be N-methylpyrrolidone (NMP), but is not limited to this.

[0217] [Negative electrode plate]

[0218] In some embodiments, the negative electrode includes a negative current collector and a lithium metal layer located on at least one side of the negative current collector, thereby enabling the assembly of a lithium metal battery cell. The lithium metal layer includes elemental lithium or an alloy of lithium metal with other metallic and / or non-metallic elements. Other metallic elements may include one or more of Sn, Zn, Al, Mg, Ag, Au, Ga, In, and Pt. Non-metallic elements may include one or more of B, C, and Si. Optionally, the total mass percentage of other metallic and / or non-metallic elements in the lithium metal layer may be less than or equal to 5%, preferably less than or equal to 3%.

[0219] In some embodiments, the negative electrode may include a negative current collector but not a lithium metal layer, thereby enabling the assembly of a negative electrode-free lithium metal battery cell. Optionally, the surface of the negative current collector of the negative electrode-free lithium metal battery cell may also be provided with an interface modification layer that can improve lithium metal deposition behavior.

[0220] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. The metal foil may be a pure metal, an alloy, or a surface-treated metal. For example, the metal foil may be copper foil. The composite current collector may include a polymer substrate and a metal material layer formed on at least one surface of the polymer substrate. For example, the metal material may include, but is not limited to, one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer substrate may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0221] [Isolation membrane]

[0222] The separator is located between the positive and negative electrodes and primarily serves to prevent internal short circuits. This disclosure does not impose any particular limitation on the type of separator; any known porous membrane with good chemical and mechanical stability can be selected.

[0223] In some embodiments, the material of the separator may include, but is not limited to, one or more of glass fiber, nonwoven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and polyimide. 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.

[0224] The separator can be a single component located between the positive and negative electrodes, or it can be attached to the surfaces of the positive and negative electrodes. Inorganic particle coatings, organic particle coatings, or organic / inorganic composite coatings can also be applied to the surface of the separator.

[0225] Metal battery cells also include an outer packaging for housing the electrode assembly and electrolyte. The outer packaging can be a rigid shell, such as a hard plastic shell, aluminum shell, or steel shell. It can also be a flexible package, such as a pouch. The flexible package can be made of plastic, such as aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), or polybutylene succinate (PBS).

[0226] Methods for preparing metal 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 metal 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 and settling, a metal battery cell is obtained.

[0227] Example

[0228] The following embodiments describe the disclosure of this disclosure 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 this disclosure. 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.

[0229] Example 1

[0230] Preparation of electrolyte

[0231] A locally concentrated electrolyte was prepared in a glove box filled with high-purity argon gas and containing water and oxygen concentrations below 1 ppm. The electrolyte salt was lithium bis(fluorosulfonyl)imide (LiFSI), the organic solvent was dimethyl ethylene glycol (DME), and the diluent was 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE). The molar ratio of LiFSI, DME, and TTE was 1:1.2:3. Boron additives as shown in Table 1 were then added, and the mixture was stirred thoroughly in the glove box to obtain the electrolyte. The mass percentage of boron additives in the electrolyte was 0.6%.

[0232] Preparation of positive electrode sheet

[0233] LiNi, the positive electrode active material 0.8 Co 0.1 Mn 0.1 O2, carbon black (positive electrode conductive agent), and polyvinylidene fluoride (PVDF) (positive electrode binder) were mixed evenly in N-methylpyrrolidone (NMP) solvent at a solid mass ratio of 97:2:1 to obtain a positive electrode slurry. The positive electrode slurry was then uniformly coated onto a positive electrode current collector, dried, cold-pressed, and slit to obtain the positive electrode sheet. The positive electrode active material is LiNi. 0.8 Co 0.1 Mn 0.1 O2 includes both single-crystal and polycrystalline morphologies.

[0234] Preparation of negative electrode sheet

[0235] Lithium foil is rolled onto the surface of copper foil to serve as the negative electrode.

[0236] Separating membrane

[0237] Polypropylene porous membrane is used as the separator.

[0238] Preparation of metal battery cells

[0239] The positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to provide isolation. The electrode assembly is then wound up and placed in an outer packaging with a receiving cavity. The prepared electrolyte is injected into the receiving cavity, and after vacuum sealing and settling, a metal battery cell is obtained.

[0240] Performance testing

[0241] (1) High-temperature cycling performance test

[0242] The metal battery cells were placed in a 60°C constant temperature chamber and charged at a constant current of 0.2C to 4.3V. Then, they were charged at a constant voltage of 4.3V to a current of 0.05C, and finally discharged at a constant current of 1C to 2.8V. This constitutes one charge-discharge cycle. The discharge capacity at this point was recorded as the initial discharge capacity. The metal battery cells were then subjected to cyclic charge-discharge tests using the same method. The capacity retention rate of the metal battery cell was calculated as (discharge capacity after cycles / initial discharge capacity) × 100%. The number of cycles required for the metal battery cell to retain 80% of its capacity was recorded.

[0243] (2) High-temperature circulating gas production test

[0244] The high-temperature circulating gas production was tested using the Yuaneng in-situ gas generator.

[0245] The metal battery cells were placed in a 60°C constant-temperature silicone oil bath, and their initial weight was recorded. The cells were then charged at a constant current of 0.2C to 4.3V, followed by constant-voltage charging at 4.3V to a current of 0.05C, and then discharged at a constant current of 1C to 2.8V. This constituted one charge-discharge cycle, and the initial discharge capacity was recorded. The metal battery cells were then subjected to cyclic charge-discharge tests using the same method, and the weight changes were recorded to calculate the gas production during the cycle. The ratio of gas production to capacity was used to characterize the high-temperature cyclic gas production performance of the metal battery cells. The capacity retention rate of the metal battery cells was calculated as (discharge capacity after cycles / initial discharge capacity) × 100%, and the gas production rate was recorded when the capacity retention rate was 80%.

[0246] (3) Transition metal dissolution test

[0247] A metal battery cell, cycled at 60°C to 80% capacity retention, is discharged at a constant current of 0.1C to 2.8V; then the metal battery cell is disassembled, and the negative electrode is removed; 30 unit areas (e.g., 1540.25 mm²) are randomly selected from the negative electrode. 2The discs were subjected to inductively coupled plasma atomic emission spectrometry (ICP) using an Agilent ICP-OES730. The amounts of Ni, Co, and Mn were calculated based on the ICP results, thus determining the leaching amounts of Ni, Co, and Mn after high-temperature cycling. The testing standard was based on EPA-6010D-2014.

[0248] (4) High-temperature storage performance test

[0249] A single metal battery cell was charged at 25°C with a constant current of 0.2C to 4.3V, then charged at 4.3V with a constant voltage until the current reached 0.05C, and finally discharged at 1C with a constant current until 2.8V. This constitutes one charge-discharge cycle, and the discharge capacity at this point is recorded as the initial discharge capacity C0. The single metal battery cell was then charged again with a constant current of 0.2C to 4.3V, and then charged at 4.3V with a constant voltage until the current reached 0.05C. At this point, the single metal battery cell was fully charged. The fully charged single metal battery cell was placed in a 60°C constant temperature chamber and stored for 30 days. After that, the single metal battery cell was removed and allowed to stand at 25°C for 3 hours, then discharged at 1C with a constant current until 2.8V, and the discharge capacity at this point was recorded as C1. The capacity retention rate of the single metal battery cell after 30 days of high-temperature storage is calculated as (C1 / C0) × 100%.

[0250] (5) Gas production test after high-temperature storage

[0251] The volume of a single metal battery cell is tested as follows: Place a beaker containing deionized water on an electronic balance and record the balance reading m1. Fix the metal battery cell in mid-air using the clamps of an iron stand, and slowly immerse it in the beaker containing deionized water until the metal battery cell is completely submerged. Record the balance reading m2. The volume V of the metal battery cell can be calculated using the formula mg = ρVP. V = (m2 - m1) × g / (ρ × P), where ρ is the density of deionized water, g is the gravitational coefficient, and P is one standard atmosphere.

[0252] Using the volume testing method described above, the volume V1 of the metal battery cell before high-temperature storage was calculated, and then the volume V2 of the metal battery cell after 30 days of high-temperature storage was calculated. The gas production of the metal battery cell after 30 days of high-temperature storage is calculated as V2 - V1. The ratio of (V2 - V1) to the capacity of the metal battery cell is used to characterize the gas production performance of the metal battery cell during high-temperature storage.

[0253] Examples 2 to 17

[0254] Except for the use of boron-based additives in the electrolyte as shown in Table 1, the preparation method and performance testing method of the metal battery cell are the same as in Example 1.

[0255] Comparative Example 1

[0256] Except that the electrolyte does not contain boron additives, the preparation method and performance testing method of the metal battery cell are the same as in Example 1.

[0257] Comparative Example 2

[0258] Except that the electrolyte does not contain boron additives and the cycle charge / discharge temperature of the metal battery cell is 25°C, the preparation method and performance testing method of the metal battery cell are the same as in Example 1.

[0259] Comparative Example 3

[0260] Except for the use of boron-based additives in the electrolyte as shown in Table 1 and the cyclic charge-discharge temperature of the metal battery cell being 25°C, the preparation method and performance testing method of the metal battery cell are the same as in Example 1.

[0261] Table 1

[0262]

[0263]

[0264]

[0265] As can be seen from the test results in Table 1, by including the boron-based additives disclosed in the electrolyte and setting the charge / discharge temperature of the metal battery cell to 40℃-70℃, the positive electrode and lithium metal negative electrode can be stabilized, the high-temperature gas production of the metal battery cell can be reduced, and the amount of transition metal dissolution can be reduced, thus enabling the metal battery cell to have good high-temperature cycle performance and high-temperature storage performance.

[0266] As can be seen from the test results of Examples 1 to 10, the fluorinated compounds of Formula 1 and Formula 2 can better improve the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0267] The test results of Examples 1, 5 and 11 show that by using two different boron-based additives, the high-temperature cycle performance and high-temperature storage performance of metal battery cells can be further improved.

[0268] Example 1-1

[0269] Except for the cycle charge / discharge temperature of the metal battery cell being 70°C and the storage temperature of the metal battery cell being 70°C, the performance testing method for the metal battery cell is the same as in Example 1.

[0270] Examples 1-2

[0271] Except for the cyclic charge-discharge temperature of the metal battery cell being 50°C and the storage temperature of the metal battery cell being 50°C, the performance testing method for the metal battery cell is the same as in Example 1.

[0272] Examples 1-3

[0273] Except for the cyclic charge-discharge temperature of the metal battery cell being 40°C and the storage temperature of the metal battery cell being 40°C, the performance testing method for the metal battery cell is the same as in Example 1.

[0274] Table 2

[0275]

[0276] As can be seen from the test results in Table 2, by setting the charge and discharge temperature of the metal battery cell to 40℃-70℃, the metal battery cell can have good cycle performance.

[0277] Examples 2-1 to 2-6

[0278] Except for the different mass ratio of boron additives in the electrolyte, the preparation method and performance testing method of the metal battery cell are the same as in Example 1.

[0279] Table 3

[0280]

[0281] The test results in Table 3 show that an appropriate amount of boron additives is beneficial for forming a stable interfacial film, reducing high-temperature gas generation and transition metal dissolution in metal battery cells, and contributing to good high-temperature cycle performance and high-temperature storage performance of the metal battery cells. However, higher boron additive content increases the negative electrode interfacial reaction, resulting in lower capacity retention of the metal battery cells.

[0282] Example 3-1

[0283] Except that the electrolyte also contains 0.2% tris(trimethylsilane) phosphate (TMSP), the preparation method and performance testing method of the metal battery cell are the same as in Example 1.

[0284] Table 4

[0285]

[0286] As can be seen from the test results in Table 4, an appropriate amount of silicon-containing deacidifying additives helps to reduce the acidity of the electrolyte, reduce the damage of acidic substances to the interfacial film, thereby helping to reduce the amount of transition metal leaching, reduce the gas production of metal battery cells, and improve the high-temperature cycle performance and high-temperature storage performance of metal battery cells.

[0287] Examples 4-1 to 4-4

[0288] Except for the different molar ratios of LiFSI, DME, and TTE in the electrolyte, the preparation method and performance testing method of the metal battery cells are the same as in Example 1.

[0289] Table 5

[0290]

[0291] As can be seen from the test results in Table 5, further adjusting the molar ratio of electrolyte salt, organic solvent, and diluent can help to further improve the performance of metal battery cells.

[0292] It should be noted that this disclosure 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 disclosure are included within the technical scope of this disclosure. 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, are also included within the scope of this disclosure without departing from the spirit of this disclosure.

Claims

1. A metal battery cell, comprising an electrode assembly and an electrolyte, wherein the electrode assembly comprises a positive electrode, a negative electrode, and a separator, the separator being located between the positive electrode and the negative electrode, characterized in that, The electrolyte comprises an organic solvent, an electrolyte salt, a diluent, and a boron-based additive. The boron-based additive is an organic compound centered on boron and contains at least one of F atoms, B-O bonds, and B-B bonds. The charge / discharge temperature of the metal battery cell is 40℃-70℃.

2. The metal battery cell according to claim 1, characterized in that, The boron-based additives include at least one of the following compounds. p and q independently represent integers from 0 to 6, R 1 Each independently represents F, C1-C3 alkyl, or C1-C3 fluoroalkyl, R 2 Each can be independently represented as F, C1-C3 alkyl, or C1-C3 fluoroalkyl; m and n independently represent integers from 0 to 4, R 3 Each independently represents F, C1-C3 alkyl, or C1-C3 fluoroalkyl, R 4 Each can be independently represented as F, C1-C3 alkyl, or C1-C3 fluoroalkyl; R 5 R 6 R 7 Each of the following can be independently represented as C1-C3 alkyl, C1-C3 fluoroalkyl, C1-C3 alkoxy, C1-C3 fluoroalkoxy, phenyl, fluorophenyl, methylphenyl or fluoromethylphenyl; s represents an integer from 1 to 5, R 8 Each of these groups independently represents F, C1-C3 alkyl, C1-C3 fluoroalkyl, cyano, or carboxyl, and R... 8 At least one of them represents a cyano or a carboxyl group; R 9 R 10 R 11 Each of these can independently represent a C1-C3 alkyl, a C1-C3 fluoroalkyl, a phenyl, a fluorophenyl, a methylphenyl, or a fluoromethylphenyl, and R 9 R 10 R 11 At least one of them represents a C1-C3 fluoroalkyl, fluorophenyl or fluoromethylphenyl; R 12 R 13 R 14 Each of these can independently represent phenyl, fluorophenyl, methylphenyl, or fluoromethylphenyl, and R 12 R 13 R 14 At least one of them represents fluorophenyl or fluoromethylphenyl.

3. The metal battery cell according to claim 2, characterized in that, The boron-based additives include at least one of the compounds of Formula 1 and Formula 2.

4. The metal battery cell according to claim 3, characterized in that, The boron-based additives include at least one of the compounds of formula 1, formula 2, and formula 3.

5. The metal battery cell according to any one of claims 2-4, characterized in that, The boron additives satisfy at least one of the following conditions (1) to (13): (1) p and q represent integers from 1 to 4 independently; (2)R 1 Each can be independently represented as either F or C1-C3 fluoroalkyl; (3)R 2 Each can be independently represented as either F or C1-C3 fluoroalkyl; (4) m and n represent integers from 1 to 4 independently; (5)R 3 Each can be independently represented as either F or C1-C3 fluoroalkyl; (6)R 4 Each can be independently represented as either F or C1-C3 fluoroalkyl; (7)R 5 R 6 R 7 Each can be independently represented as a C1-C3 fluoroalkyl, C1-C3 fluoroalkoxy, fluorophenyl, or fluoromethylphenyl. (8)R 5 R 6 R 7 same; (9) s represents an integer from 1 to 3; (10)R 9 R 10 R 11 Each can be independently represented as a C1-C3 fluoroalkyl, fluorophenyl, or fluoromethylphenyl. (11)R 9 R 10 R 11 same; (12)R 12 R 13 R 14 Each can be used independently to represent either fluorophenyl or fluoromethylphenyl; (13)R 12 R 13 R 14 same.

6. The metal battery cell according to any one of claims 2-5, characterized in that, The boron-based additives include at least one of the following compounds.

7. The metal battery cell according to any one of claims 1-6, characterized in that, The boron-based additive accounts for 0.1%-1% of the mass of the electrolyte.

8. The metal battery cell according to any one of claims 1-7, characterized in that, The electrolyte also includes a silicon-containing acid-removing additive.

9. The metal battery cell according to claim 8, characterized in that, The silicon-containing deacidifying additive includes one or more of tris(trimethylsilane) phosphate, silazane, N-trimethylsilylimidazolium, and tris(trimethylsilane)borate; and / or, The silicon-containing acid-removing additive accounts for 0.01%-0.5% of the mass of the electrolyte.

10. The metal battery cell according to any one of claims 1-9, characterized in that, The electrolyte salt comprises one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium dioxalate borate, lithium difluorooxalate borate, lithium difluorodioxalate phosphate, and lithium tetrafluorooxalate phosphate; and / or, The organic solvent includes ether compounds; and / or, The diluent includes one or more of fluoroether diluents, aromatic diluents, and fluorinated aromatic diluents.

11. The metal battery cell according to claim 10, characterized in that, The electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide and lithium bis(trifluoromethanesulfonyl)imide; and / or, The organic solvent includes one or more of methyl n-butyl ether, tetrahydrofuran, ethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol diethyl ether, 1,2-dimethoxypropane, 1,3-dimethoxypropane, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether; and / or, The diluent includes 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl, 1-(1,1,2,2-tetrafluoroethoxy)propane, 1,1,2,2-tetrafluoroethyl ether, bis(2,2,2-trifluoroethyl) ether, difluoromethyl 2,2,3,3-tetrafluoropropyl ether, heptafluoropropyl 1,2,2,2-tetrafluoroethyl ether, 2,2,3 One or more of the following: 3,3-pentafluoropropyl-1,1,2,2-tetrafluoroethyl ester, bis-(1,2,2,2-tetrafluoroethyl) ether, 1,1,2,3,3,3-pentafluoropropyl difluoromethyl ether, 1,1,2,3,3,3-pentafluoropropyl-2,2,2-trifluoroethyl ether, 1H,1H,5H-octafluoropentyl-1,1,2,2-tetrafluoroethyl ether, benzene, 3-fluorobenzene, m-difluorobenzene, 1,3,5-trifluorobenzene, and anisole.

12. The metal battery cell according to any one of claims 1-11, characterized in that, The molar ratio of the electrolyte salt, the organic solvent, and the diluent is 1:(0.8-3):(0.5-5).

13. The metal battery cell according to any one of claims 1-12, characterized in that, The positive electrode includes a positive current collector and a positive electrode film layer located on at least one side of the positive current collector. The positive electrode film layer includes a positive electrode active material, which includes a lithium transition metal oxide. The lithium transition metal oxide includes Ni element, and the molar percentage of Ni element in the transition metal elements of the lithium transition metal oxide is more than 80%.

14. The metal battery cell according to claim 13, characterized in that, The volumetric particle size Dv50 of the positive electrode active material is 2μm-12μm; and / or, The positive electrode active material comprises a single-crystal lithium transition metal oxide, and the area of ​​the single-crystal lithium transition metal oxide is 20%-100% of the total area of ​​the positive electrode active material.

15. The metal battery cell according to claim 13 or 14, characterized in that, The porosity of the positive electrode film is 13%-26%.

16. The metal battery cell according to any one of claims 1-15, characterized in that, The negative electrode sheet includes a negative current collector and a lithium metal layer located on at least one side of the negative current collector. The lithium metal layer includes elemental lithium metal or an alloy formed by lithium metal and other metal elements and / or non-metal elements. Alternatively, the negative electrode sheet includes a negative current collector but does not include a lithium metal layer.

17. A battery device, characterized in that, It includes the metal battery cells described in any one of claims 1-16.

18. An electrical appliance, characterized in that, Includes the metal battery cell as described in any one of claims 1-16 or the battery device as described in claim 17.

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