Electrolyte, battery, battery pack and electric equipment

Abstract

The invention relates to the technical field of lithium ion batteries, and particularly discloses an electrolyte, a battery, a battery pack and electric equipment. The electrolyte comprises a first additive and a second additive, wherein the first additive comprises a fullerene-containing fluorobenzene solution; the second additive is a boric acid ester film-forming agent, the structural general formula of the boric acid ester film-forming agent is B (OR) 3, and R is an organic group. Therefore, according to the electrolyte, the gas production phenomenon in the battery circulation process is greatly reduced, the battery circulation performance is effectively improved, the circulation life is prolonged, meanwhile, the electrolyte has good adaptability with the ternary-doped lithium iron manganese phosphate battery, the circulation capacity retention rate is high, capacity fading or structural damage cannot be caused, and the service life of the battery is prolonged. On the premise of not sacrificing the core electrical property of the battery, the circulating gas production is reduced, so that the safety performance of the lithium ion battery is remarkably improved, and the key contradiction that the high energy density and the high safety of the lithium battery are difficult to consider is relieved.

Description

Technical Field

[0001] This application relates to the field of battery technology, specifically to an electrolyte, a battery, a battery pack, and an electrical device. Background Technology

[0002] Currently, lithium-ion batteries (LIBs) are being developed towards higher energy densities to meet the extended battery life requirements of electronic devices. High-nickel NCM (LiNi) batteries are a prime example. x Co y Mn 1-x-y (x≥0.8) with up to 200 mA hg -1 The specific capacity of lithium iron phosphate (LFP) has been widely used. However, with the increase of nickel content, its cycle stability and thermal stability decrease significantly. To balance performance and safety, lithium iron phosphate is blended with ternary materials to compensate for the shortcomings of single cathode materials. The cathode system obtained by co-blending lithium iron phosphate with ternary materials (LMFP-NCM) can maintain high voltage (4.4V) and high volumetric energy density (495-628Wh / L) while also having advantages such as low cost, high safety, and long cycle life.

[0003] However, under high-voltage charging conditions, high-nickel ternary cathode materials undergo deep delithiation, resulting in highly oxidized Ni. 4+ Tends to be reduced to Ni 3+ To maintain charge balance, oxygen in the crystal lattice is forced to be released, thereby forming superoxide radicals (O2), which have strong oxidizing properties. - This free radical not only exacerbates the structural degradation of the cathode material but also undergoes violent side reactions with cyclic carbonate solvents (such as EC) in the electrolyte, producing gases such as O2, CO, and CO2 and releasing heat. Particularly dangerous is that the oxygen generated further accelerates the decomposition and oxidation of the electrolyte. The generated gases accumulate on the electrode surface, forming an insulating layer that hinders the normal transport of lithium ions. This not only significantly increases the battery's internal resistance but also continuously consumes active lithium and electrolyte due to the side reactions, ultimately leading to rapid capacity decay and shortened cycle life. Even more dangerous is that gas accumulation increases the internal pressure of the battery, causing battery bulging (especially in pouch cells), and even leading to structural deformation or seal failure. In extreme cases, these flammable gases (such as H2, CO, CH4) may participate in and exacerbate a chain of exothermic reactions inside the battery at high temperatures, significantly increasing the risk of thermal runaway (smoke, fire, explosion), seriously threatening safety. Furthermore, some side reactions may also generate toxic gases such as hydrogen fluoride (HF), which, if leaked, pose a threat to the environment and human health. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in related technologies. To this end, one objective of this application is to provide an electrolyte, a battery, a battery pack, and an electrical device. This application significantly reduces gas generation during battery cycling by introducing fullerenes and borate ester film-forming agents into the electrolyte, effectively improving battery cycle performance and extending cycle life. Simultaneously, the electrolyte of this application exhibits good compatibility with ternary hybrid manganese iron phosphate batteries, maintaining high cycle capacity retention without causing capacity decay or structural damage. This reduces cycle gas generation without sacrificing the core electrical performance of the battery, thereby significantly improving the safety performance of lithium-ion batteries and alleviating the critical contradiction between high energy density and high safety in lithium batteries.

[0005] In a first aspect, this application provides an electrolyte. According to an embodiment of this application, the electrolyte comprises: a first additive, the first additive comprising a fluorobenzene solution containing fullerene (FB-C). 60 (Solution); second additive, the second additive being a borate ester film-forming agent, the borate ester film-forming agent having the general structural formula B(OR)3, where R is an organic group.

[0006] This application significantly reduces battery cycle gas generation by introducing a first additive and a second additive into the electrolyte, effectively improving battery cycle performance and extending cycle life. Among them, the oxygen free radical scavenger FB-C... 60 The solution effectively suppresses gas generation during battery charging and discharging; borate ester film-forming agents, by capturing active oxygen species at the positive electrode and forming a dense CEI film in situ, achieve the effect of suppressing gas generation from electrolyte decomposition. Simultaneously, fullerenes and borate ester film-forming agents have a synergistic effect: borate ester film-forming agents can block oxygen and improve the dispersibility of fullerenes, while fullerenes can remove residual superoxide radicals in the system. Together, they form a full-chain protection, achieving a "1+1>2" effect. Furthermore, the electrolyte of this application exhibits good compatibility with ternary blended manganese iron phosphate batteries, with high battery cycle capacity retention, and does not cause capacity decay or structural damage. It can significantly improve the safety performance of lithium-ion batteries by reducing cycle gas generation without sacrificing the core electrical performance of the battery, alleviating the critical contradiction between high energy density and high safety in lithium batteries.

[0007] In addition, the electrolyte according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the organic group includes C 1-10 Alkyl, C 1-10 Haloalkyl, C 1-10 Silyl, C 2-10 At least one of alkenyl, polyethylene glycol residue, 3-7 membered cycloalkyl, 3-7 membered heterocycloalkyl, 3-7 membered aryl, and 3-7 membered heteroaryl.

[0008] In some embodiments of this application, the mass percentage of fullerene is 1-5% based on the total mass of the fullerene-containing fluorobenzene solution.

[0009] In some embodiments of this application, the borate film-forming agent includes at least one of tris(hexafluoroisopropyl) borate (THFPB), tris(trimethylsilyl) borate (TMSB), and polyethylene glycol borate (BPEs).

[0010] In some embodiments of this application, the mass ratio of the first additive to the second additive is 1:(0.3~30).

[0011] In some embodiments of this application, the first additive accounts for 0.1% to 5% of the mass of the electrolyte.

[0012] In some embodiments of this application, the second additive accounts for 1% to 38.5% of the mass of the electrolyte.

[0013] In some embodiments of this application, the electrolyte further comprises lithium salt and organic solvent.

[0014] In some embodiments of this application, the lithium salt includes at least one of inorganic lithium salt and organic lithium salt.

[0015] In some embodiments of this application, the concentration of the lithium salt in the electrolyte is 1~4 mol / L.

[0016] In some embodiments of this application, the organic solvent is selected from carbonate solvents.

[0017] In some embodiments of this application, the organic solvent accounts for 60-85% of the mass of the electrolyte.

[0018] In a second aspect, this application proposes a battery. According to an embodiment of this application, the battery includes the electrolyte of the first aspect. As described above, the fullerene and borate ester film-forming agent in the electrolyte of this application have a synergistic effect, significantly reducing battery cycle gas generation, electrolyte decomposition, and electrode structure damage through a full-chain protection of "inhibiting reactive oxygen generation—scavenging residual free radicals," thereby extending cycle life. Simultaneously, this electrolyte exhibits good compatibility with ternary blended manganese iron phosphate batteries, significantly improving battery safety performance without sacrificing core electrical performance. Therefore, the battery of this application possesses excellent cycle performance and safety performance.

[0019] In addition, the battery according to the above embodiments of this application may also have the following additional technical features: In some embodiments of this application, the battery further includes: a positive electrode sheet, the positive electrode sheet including a positive electrode active layer, the positive electrode active layer including a positive electrode active material, the positive electrode active material being LiMn. x Fe 1-x PO4-LiNi a Co b Mn 1-a-b O2, where 0.5 ≤ x < 1; 0.8 ≤ a < 1, 0.1 ≤ b ≤ 0.33, LiNi a Co b Mn 1-a-b O2 and LiMn x Fe 1-x The mass ratio of PO4 is ≥0.1%.

[0020] In some embodiments of this application, the nickel content 'a' in the positive electrode active material and the mass ratio 'c' of the additive in the electrolyte satisfy the following relationship: 1.3 ≤ a : c ≤ 6.8; the additive is the first additive and the second additive in the electrolyte described in the first aspect.

[0021] In a third aspect, this application proposes a battery pack. According to embodiments of this application, the battery pack includes the electrolyte described in the first aspect or the battery described in the second aspect. Therefore, the battery pack of this application possesses excellent cycle performance and safety performance. Those skilled in the art will understand that this battery pack possesses all the features and advantages of the electrolyte described above, which will not be elaborated further here.

[0022] In a fourth aspect, this application proposes an electrical device. According to embodiments of this application, the electrical device includes the electrolyte described in the first aspect, the battery described in the second aspect, or the battery pack described in the third aspect. Therefore, the electrical device of this application possesses excellent cycle performance and safety performance. Those skilled in the art will understand that this electrical device possesses all the features and advantages of the electrolyte described above, which will not be elaborated further here.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Detailed Implementation

[0024] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0025] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0026] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0027] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0028] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values ​​of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).

[0029] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.

[0030] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0031] In this application, the term "alkyl" refers to a straight-chain or branched saturated monovalent or divalent hydrocarbon group. For example, "C 1-10 "Alkyl" should be understood as representing a straight-chain or branched saturated monovalent or divalent hydrocarbon group having 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms. The alkyl group includes, but is not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, isopropyl, isobutyl, sec-butyl, tert-butyl, isopentyl, 2-methylbutyl, 1-methylbutyl, 1-ethylpropyl, 1,2-dimethylpropyl, neopentyl, 1,1-dimethylpropyl, 4-methylpentyl, 3-methylpentyl, 2-methylpentyl, 1-methylpentyl, 2-ethylbutyl, 1-ethylbutyl, 3,3-dimethylbutyl, 2,2-dimethylbutyl, 1,1-dimethylbutyl, 2,3-dimethylbutyl, 1,3-dimethylbutyl or 1,2-dimethylbutyl, methylene, ethylidene, propylene, 1-methylpropylene, butylidene, etc.

[0032] In this application, the term "halogenated alkyl" refers to an alkyl group substituted with one or more halogens. For example, "C 1-10 "Halogenated alkyl" should be understood as referring to a C that has been substituted by one or more halogens. 1-10 Alkyl groups. The alkyl halogenated groups include, but are not limited to, trifluoromethyl, difluoromethyl, fluoromethyl, trichloromethyl, pentafluoroethyl, pentachloroethyl, 2,2,2-trifluoroethyl, 1,2-difluoroethyl, 1,2-dibromoethyl, hexafluoroisopropyl, heptafluoropropyl, heptachloropropyl, 3-bromo-2-fluoropropyl, etc.

[0033] In this application, the terms "halogenated group" or "halogen" refer to fluorine, chlorine, bromine, or iodine.

[0034] In this application, the term "silyl group" refers to a monovalent substituent remaining after a primary, secondary, tertiary, or quaternary carbon atom in the corresponding carbon-based skeleton has been replaced by a silicon atom.

[0035] In this application, the term "alkenyl" refers to a straight-chain or branched monovalent hydrocarbon group having at least one carbon-carbon sp2 double bond, including the orientation of "cis" and "trans", or the orientation of "E" and "Z". The alkenyl group may optionally be substituted by one or more substituents described in this invention. In one embodiment, the alkenyl group comprises 2-10 carbon atoms; in another embodiment, the alkenyl group comprises 3-10 carbon atoms; in yet another embodiment, the alkenyl group comprises 2-6 carbon atoms; and in still another embodiment, the alkenyl group comprises 2-4 carbon atoms. Examples of alkenyl groups include, but are not limited to, vinyl (-CH=CH2), allyl (-CH2CH=CH2), etc.

[0036] In this application, the term "polyethylene glycol residue" refers to the monovalent free radical fragment left after removing a hydrogen atom (or other leaving group) from any terminal hydroxyl group or segment of polyethylene glycol.

[0037] In this application, the term "cycloalkyl" refers to a monovalent or polyvalent saturated monocyclic or bicyclic ring containing 3-7 cyclic carbon atoms. In one embodiment, the cycloalkyl group comprises 3-6 cyclic carbon atoms; in another embodiment, the cycloalkyl group comprises 3-5 cyclic carbon atoms; and in yet another embodiment, the cycloalkyl group comprises 3-4 cyclic carbon atoms. The cycloalkyl group may be independently unsubstituted or substituted by one or more substituents described in this invention.

[0038] In this application, the term "heterocyclic alkyl" should be understood to mean a saturated monocyclic or bicyclic ring having 3, 4, 5, 6, or 7 ring atoms, wherein 1, 2, or 3 ring atoms are selected from N, O, and S. Unless otherwise stated, "3- to 7-membered heterocyclic alkyl" may be attached to the remainder of the molecule by a carbon atom or a heteroatom. It should be understood that when the total number of S and O atoms in a heterocyclic group exceeds 1, these heteroatoms are not adjacent to each other. Examples of heterocyclic alkyl groups include, but are not limited to: oxobutyl, dioxopentyl, imidazoalkyl, thiazoalkyl, isothiazolyl, oxazolyl, isoxazolyl, morpholinyl, piperidinyl, piperazine, pyrrolyl, pyrazolyl, tetrahydrofuranyl, tetrahydropyranyl, and tetrahydrothiaranyl.

[0039] In this application, the term "aryl" refers to an aromatic hydrocarbon substituent, which may be a monocyclic or fused together or covalently linked monocyclic or polycyclic (e.g., one to three rings). The term "heteroaryl" refers to a plurality of aryl groups (or rings) comprising one to four heteroatoms selected from N, O, and S (in the case of polycyclic groups, in each monocyclic ring), wherein the nitrogen and sulfur atoms are optionally oxidized, and the nitrogen(s) atoms(s) are optionally quaternized. Heteroaryl groups may be attached to the remainder of the molecule via carbon atoms or heteroatoms. Non-limiting examples of aryl and heteroaryl groups include: phenyl, 1-naphthyl, 2-naphthyl, 4-biphenyl, 1-pyrrole, 2-pyrrole, 3-pyrrole, 3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl, 4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isooxazolyl, 4-isooxazolyl, 5-isooxazolyl, 2-thiazolyl. 4-Thiazolyl, 5-Thiazolyl, 2-furanyl, 3-furanyl, 2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl, 4-pyrimidinyl, 5-benzothiazolyl, purinel, 2-benzimidazolyl, 5-indolyl, 1-isoquinolinyl, 5-isoquinolinyl, 2-quinoxalinyl, 5-quinoxalinyl, 3-quinolinyl, and 6-quinolinyl.

[0040] Ternary materials are widely used as cathode materials for electric vehicle batteries due to their high energy density. However, high-nickel ternary materials suffer from problems such as poor room temperature cycling performance, increased DCIR (direct current resistance under specific load and discharge current) after cycling, severe gas generation after cycling, and poor safety performance. To solve the above problems of high-nickel ternary materials, current technical solutions mainly focus on the following three aspects: (1) Surface coating, such as spinel phase Li4Mn5O 12 (1) Physical barriers are constructed using anti-spinel Mg2TiO4, etc.; (2) Bulk doping, such as doping with B, Zr, Sn, etc., directly stabilizes lattice oxygen by enhancing metal-oxygen bonds or occupying oxygen coordination sites in the lattice, thereby reducing oxygen release; (3) Electrolyte functional additives, compared with the modification of the positive electrode surface by coating or doping to improve interface stability, directly introducing film-forming additives that can improve the oxidation stability of the electrolyte by modifying the electrode interface is a simpler and more efficient way.

[0041] Based on this, this application addresses the technical problem of superoxide emission catalyzing electrolyte solvent oxidation and gas generation in lithium manganese iron phosphate-ternary co-doped cathode (LMFP-NCM) batteries under high voltage conditions, leading to battery capacity decay and safety hazards. It provides an electrolyte containing a free radical scavenging additive. This electrolyte can improve its stability by scavenging superoxide free radicals and suppressing gas generation. It also exhibits good compatibility with lithium batteries, reducing gas generation during battery cycling and thus simultaneously improving the battery's overall electrochemical performance (such as cycle life) and safety performance.

[0042] In a first aspect of the application, this application proposes an electrolyte. According to an embodiment of this application, the electrolyte comprises: a first additive, the first additive comprising a fluorobenzene solution containing fullerene (FB-C) 60 (Solution); second additive, the second additive being a borate ester film-forming agent, the borate ester film-forming agent having the general structural formula B(OR)3, where R is an organic group.

[0043] This application significantly reduces battery cycle gas generation by introducing a first additive and a second additive into the electrolyte, thereby effectively improving battery cycle performance and extending cycle life. The first additive is FB-C. 60 In solution, this additive can act as an oxygen free radical scavenger, effectively suppressing gas generation during battery charging and discharging. The fluorobenzene FB component can simply and efficiently solve the problem of fullerene C… 60 Solubility issues in electrolytes, while controlling C 60 The concentration—too high a concentration will decrease its solubility, while too low a concentration will not meet the requirements for free radical scavenging. From the perspective of the mechanism of action, C 60The molecule possesses numerous conjugated π bonds. When a superoxide radical approaches, its conjugated system can accept unpaired electrons from the radical via electron transfer, transforming the superoxide radical into a relatively stable peroxide ion. Meanwhile, C... 60 It can achieve reversible oxidation on its own; and a single C 60 The molecule can react continuously with multiple superoxide radicals, exhibiting extremely high scavenging efficiency. The second additive is a borate ester film-forming agent. Due to the electron-deficient nature of boron atoms, this type of additive can capture and neutralize superoxide radicals (O2) released from the positive electrode. - Singlet oxygen () 1 Highly reactive oxygen species such as O2 are preferentially oxidized and decomposed on the positive electrode surface, forming a dense and stable cathode electrolyte interface (CEI) film. This effectively blocks direct contact between the positive electrode material and the electrolyte, thereby inhibiting electrolyte decomposition and gas generation. Furthermore, the combined use of fullerene and borate esters achieves a synergistic effect of "1+1>2": borate esters form the interfacial film, reducing the generation of reactive oxygen species at the source and blocking contact between the positive electrode and the electrolyte, thus mitigating electrolyte oxidative decomposition; fullerene, on the other hand, is responsible for scavenging the small amount of residual highly reactive superoxide radicals in the system. Together, they form a complete chain of protection: "inhibition of generation—residual removal." Simultaneously, borate esters improve the compatibility and dispersibility of fullerene in the electrolyte system, ensuring that fullerene fully exerts its free radical scavenging effect.

[0044] In some embodiments of this application, the mass percentage of fullerene in the fluorobenzene solution containing fullerene is 1-5%, based on the total mass of the solution. For example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any range of the above values. Therefore, by keeping the mass percentage of fullerene within the above range, the solubility of fullerene in the electrolyte and its free radical scavenging efficiency can be balanced, ensuring its stable oxygen free radical capture function while guaranteeing the compatibility between the electrolyte and the battery system. If the mass percentage of fullerene is too high, it will exceed the solubilizing ability of the fluorobenzene component, making it difficult for fullerene to disperse uniformly in the electrolyte or even causing it to precipitate, thus failing to effectively scavenge superoxide free radicals. If the mass percentage of fullerene is too low, its effective concentration in the electrolyte is insufficient, the electron transfer ability of the conjugated π bond cannot be fully utilized, and the scavenging efficiency for superoxide free radicals will decrease significantly, failing to achieve the technical effect of suppressing gas generation during battery cycling.

[0045] In some embodiments of this application, the organic group includes C 1-10 Alkyl, C 1-10 Haloalkyl, C 1-10 Silyl, C 2-10The borate ester film-forming agent comprises at least one of alkenyl, polyethylene glycol residue, 3-7 membered cycloalkyl, 3-7 membered heterocycloalkyl, 3-7 membered aryl, and 3-7 membered heteroaryl. In some embodiments of this application, the borate ester film-forming agent includes at least one of tris(hexafluoroisopropyl) borate, tris(trimethylsilyl) borate, and polyethylene glycol borate (BPEs). Therefore, the above-mentioned borate ester film-forming agents, due to their electron-deficient boron atom structure, can efficiently capture and neutralize highly reactive oxygen species released by the positive electrode under high voltage, reducing the inducing factors of electrolyte oxidation and decomposition from the source and directly alleviating the problem of gas generation during battery cycling. Simultaneously, this type of film-forming agent can preferentially oxidize and decompose on the positive electrode surface to form a dense, stable CEI film with high ion conductivity, and exhibits good synergistic compatibility with fullerenes, perfectly meeting the application requirements of high-voltage systems in ternary mixed lithium manganese iron phosphate (LMFP-NCM) batteries.

[0046] In some embodiments of this application, the mass ratio of the first additive to the second additive is 1:(0.3~30). For example, it can be 1:0.3, 1:0.5, 1:1, 1:2, 1:5, 1:8, 1:10, 1:12, 1:15, 1:18, 1:20, 1:22, 1:25, 1:28, 1:30, or any range of the above values. Therefore, by ensuring the mass ratio of the first additive to the second additive is within the above range, it is possible to further ensure that both additives fully exert their synergistic effect in the electrolyte system, achieving full-chain protection of "inhibiting reactive oxygen species generation—removing residual free radicals," ensuring the compatibility of the electrolyte with the target battery system, and improving battery cycle life and safety without sacrificing core electrical performance.

[0047] In some embodiments of this application, the mass percentage of the first additive in the electrolyte is 0.1% to 5%. For example, it can be 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, etc., or it can be any range of the above values. Therefore, by limiting the mass percentage of the first additive in the electrolyte to the above range, its free radical scavenging efficiency and dispersibility in the electrolyte can be further improved, thereby suppressing gas generation during battery cycling, effectively improving the cycle performance of the battery, and further improving the cycle life and safety performance of the battery.

[0048] In some embodiments of this application, the second additive accounts for 1% to 38.5% of the mass of the electrolyte. For example, it can be 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 38.5%, or any range of the above values. Therefore, by limiting the mass percentage of the second additive in the electrolyte to the above range, it is possible to further ensure the formation of a thermally stable CEI film at the positive electrode-electrolyte interface, fully capture highly reactive oxygen species released from the positive electrode, improve the effect of suppressing electrolyte decomposition and gas production, effectively improve the cycle performance of the battery, and further improve the cycle life and safety performance of the battery.

[0049] In some embodiments of this application, the electrolyte further comprises a lithium salt, which serves to provide migratable Li during battery charging and discharging. + This supports the insertion / deintercalation cycle of lithium ions between the positive and negative electrodes, thereby realizing the mutual conversion of chemical energy and electrical energy. In the embodiments of this application, the specific type of lithium salt is not particularly limited, and those skilled in the art can select it according to actual needs. As some specific embodiments, the lithium salt includes at least one of inorganic lithium salts and organic lithium salts. Exemplarily, inorganic lithium salts include one or more of lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), and lithium hexafluorophosphate (LiPF6); exemplarily, organic lithium salts include one or more of lithium bis(oxalato)borate (LiBOB), lithium difluorooxalato)borate (LiDFOB), lithium bis(difluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0050] In some embodiments of this application, the concentration of the lithium salt in the electrolyte is 1~4 mol / L. For example, it can be 1 mol / L, 1.5 mol / L, 2 mol / L, 2.5 mol / L, 3 mol / L, 3.5 mol / L, 4 mol / L, or any range of the above values. Therefore, by limiting the concentration of the lithium salt in the electrolyte within the above range, it is possible to further ensure the provision of a suitable amount of migratable lithium ions, further ensure that the ionic conductivity and viscosity of the electrolyte are within a reasonable range, and further improve the high and low temperature performance and power performance of the battery.

[0051] In some embodiments of this application, the electrolyte further includes an organic solvent, which is a major component of the electrolyte and should have high solubility of the electrolyte salt to ensure high ionic conductivity. The specific type is not particularly limited, and those skilled in the art can select according to actual needs. As some preferred embodiments, the organic solvent includes carbonate solvents. Exemplarily, carbonate solvents include at least one of propylene carbonate, ethylene carbonate (EC), fluoroethylene carbonate, ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate, methyl acetate, and ethyl propionate. All of the above-mentioned carbonate solvents can provide strong dissociation capabilities, ensuring the concentration of sodium ions in the electrolyte. Preferably, at least one of propylene carbonate and ethylene carbonate is preferred. More preferably, the organic solvent includes a mixture of ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0052] In some embodiments of this application, the organic solvent accounts for 60-85% of the mass of the electrolyte. For example, it can be 60%, 62%, 65%, 68%, 70%, 72%, 75%, 78%, 80%, 82%, 85%, etc., or any range of the above values. Therefore, by limiting the mass percentage of the organic solvent in the electrolyte to the above range, the electrolyte can be further ensured to have excellent ionic conductivity, while guiding the formation of a moderately thick, dense, stable, and highly ionicly conductive SEI and CEI film on the electrode surface, further improving the high and low temperature performance and power performance of the battery.

[0053] In a second aspect, this application proposes a battery. According to an embodiment of this application, the battery includes the electrolyte described in the first aspect. As previously stated, the fullerenes and borate ester film-forming agents in the electrolyte of this application have a synergistic effect, significantly reducing battery cycle gas generation, electrolyte decomposition, and electrode structure damage through a full-chain protection mechanism of "inhibiting reactive oxygen generation—scavenging residual free radicals," thereby extending cycle life. Simultaneously, this electrolyte exhibits good compatibility with ternary blended manganese iron phosphate batteries, significantly improving battery safety performance without sacrificing core electrical performance. Therefore, the battery of this application possesses excellent cycle performance and safety performance.

[0054] In some embodiments of this application, the battery further includes: a positive electrode sheet, the positive electrode sheet including a positive electrode active layer, the positive electrode active material layer including a positive electrode active material, the positive electrode active material being LiMn. x Fe 1-x PO4-LiNi a Co b Mn 1-a-b O2, where 0.5 ≤ x < 1; 0.8 ≤ a < 1, 0.1 ≤ b ≤ 0.33, LiNi aCo b Mn 1-a-b O2 and LiMn x Fe 1-x The mass ratio of PO4 is ≥0.1%. Among them, the above-mentioned positive electrode active material is a high-nickel ternary material. The high nickel content can improve the specific capacity and energy density of the positive electrode, which meets the requirements of power batteries for long driving range. At the same time, the high-nickel ternary material has a higher working voltage platform, which can match the high voltage tolerance characteristics of the electrolyte of this application and give full play to the gas suppression and film formation effects of electrolyte additives.

[0055] It should be noted that the "LiMn" described in this application x Fe 1-x PO4-LiNi a Co b Mn 1-a-b "O2" refers to LiNi a Co b Mn 1-a-b O2 and LiMn x Fe 1-x A mixture of PO4.

[0056] In some embodiments of this application, the nickel content *a* in the positive electrode active material and the mass ratio *c* of the additive in the electrolyte satisfy the following relationship: 1.3 ≤ *a* : *c* ≤ 6.8; the additive is the first additive and the second additive in the electrolyte described in the first aspect. Based on this ratio, by selectively adjusting the total mass ratio *c* of the composite additive, different nickel contents (*a* values) of LiMn can be achieved. x Fe 1-x PO4-LiNi a Co b Mn 1-a-b The adaptation of the O2 composite cathode system ensures that the battery maintains excellent cycle stability and safety performance under the full nickel content gradient.

[0057] In some embodiments of this application, the positive electrode sheet further includes a positive current collector, and the positive active layer is disposed on at least one surface of the positive current collector. In some embodiments of this application, the positive current collector may include a metal foil or a composite positive current collector. For example, the metal foil may be aluminum foil. The composite positive current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. For example, the composite negative current collector can be formed by forming a metal material (aluminum, aluminum alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0058] In some embodiments of this application, the positive electrode active layer may optionally include a positive electrode conductive agent. As an example, the positive electrode conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0059] In some embodiments of this application, the positive electrode active layer may optionally include a positive electrode binder. As an example, the positive electrode binder may include at least one of polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyethylene ether, polymethyl methacrylate (PMMA), polyhexamethylene propylene, and styrene-butadiene rubber (SBR).

[0060] In some embodiments of this application, the battery further includes a negative electrode sheet and a separator. In embodiments of this application, the negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on at least one surface of the negative electrode current collector, the negative electrode active layer including a negative electrode active material.

[0061] In some embodiments of this application, the negative electrode current collector may be a metal foil or a composite current collector. For example, copper foil may be used as the metal foil. The composite current collector may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.).

[0062] In some embodiments of this application, the negative electrode active material may be a negative electrode active material known in the art for use in batteries. As an example, the negative electrode active material may include at least one of the following materials: graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, lithium titanate, etc. Silicon-based materials may include at least one of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include at least one of elemental tin, tin oxide compounds, and tin alloys.

[0063] In some embodiments of this application, the negative electrode active layer may optionally include a negative electrode binder. The negative electrode binder may include at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0064] In some embodiments of this application, the negative electrode active layer may optionally include a negative electrode conductive agent. The negative electrode conductive agent may include at least one selected from superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0065] In some embodiments of this application, the negative electrode active layer may optionally include other additives, such as thickeners (e.g., sodium carboxymethyl cellulose (CMC-Na)).

[0066] This application does not impose any particular limitation on the type of separator membrane; any known porous separator membrane with good chemical and mechanical stability can be selected. In some embodiments of this application, the material of the separator membrane may include at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, or polyvinylidene fluoride.

[0067] In a third aspect, this application proposes a battery pack. According to embodiments of this application, the battery pack includes the electrolyte described in the first aspect or the battery described in the second aspect. Therefore, the battery pack of this application possesses excellent cycle performance and safety performance. Those skilled in the art will understand that this battery pack possesses all the features and advantages of the electrolyte described above, which will not be elaborated further here.

[0068] In some embodiments of this application, the battery pack can be a battery module, and the number of battery cells contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0069] In some embodiments of this application, the battery pack can be a battery module, and the number of battery modules contained in the battery module can be one or more. The specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0070] In a fourth aspect, this application proposes an electrical device. According to embodiments of this application, the electrical device includes the electrolyte described in the first aspect, the battery described in the second aspect, or the battery pack described in the third aspect. Therefore, the electrical device of this application possesses excellent cycle performance and safety performance. Those skilled in the art will understand that this electrical device possesses all the features and advantages of the electrolyte described above, which will not be elaborated further here.

[0071] Specifically, the aforementioned electrical equipment can include, but is not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc., and spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0072] The following will explain the solution of this application with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0073] Example 1 1. Preparation of electrolyte Preparation of the first additive: Weigh a certain amount of C 60 FB-C was prepared by dissolving it in fluorobenzene FB to obtain a 3% (w / w) solution. 60 Saturated solution. The second additive is tris(hexafluoroisopropyl) borate (THFPB).

[0074] In a glove box with an oxygen content <10ppm and a moisture content <1ppm, ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC) were mixed in a volume ratio of EC:DMC:EMC = 2:3:5 to obtain a mixed organic solvent. Molecular sieves cooled to 110°C were added to the mixed organic solvent and allowed to stand for 48 hours to remove moisture. LiPF6 was weighed in a high-purity argon glove box and dissolved in the dehydrated organic solvent at a molar concentration of 1 mol / L. Then, the prepared first and second additives were added in proportion, wherein the first additive accounted for 3 wt% of the electrolyte, the mass ratio of the first additive to the second additive was 1:1, and the ratio of the nickel content in the positive electrode active material to the total mass of the two additives was 1.5.

[0075] 2. Preparation of the positive electrode sheet The positive electrode active material (85% LiMn) 0.6 Fe 0.4 PO4+15% LiNi 0.8 Co 0.1 Mn 0.1 O2), conductive agent carbon black, binder PVDF, and dispersant sodium carboxymethyl cellulose (CMC) are mixed evenly in a stirring device at a mass ratio of 97.2:0.9:1.7:0.2. Then, a certain amount of solvent N-methylpyrrolidone (NMP) is added and stirred to form a uniform slurry. The slurry is then coated onto the positive current collector aluminum foil using a coating machine to obtain the positive electrode sheet.

[0076] 3. Preparation of negative electrode sheet The negative electrode active material graphite, conductive agent carbon black, thickener CMC and binder SBR are dispersed in deionized water at a mass ratio of 97:0.6:1.1:1.3 and mixed evenly to obtain a negative electrode slurry. The negative electrode slurry is then coated on both sides of the negative electrode current collector copper foil to obtain a negative electrode sheet.

[0077] 4. Separating membrane A 25μm thick polyethylene diaphragm is used as the diaphragm.

[0078] 5. Battery assembly The prepared positive electrode, separator, and negative electrode are stacked in sequence, with the separator positioned between the positive and negative electrodes to separate them. Electrolyte is injected, and after capacity separation and formation, the cells are assembled into a 505070 type soft-pack battery with a rated capacity of 2.0Ah (1C=2A).

[0079] Example 2 The preparation method in this embodiment is basically the same as that in Example 1, except that: a certain amount of C is weighed. 60 FB-C was prepared by dissolving it in fluorobenzene FB to obtain a mass fraction of 1%. 60 Saturated solution.

[0080] Example 3 The preparation method in this embodiment is basically the same as that in Example 1, except that: a certain amount of C is weighed. 60 FB-C was prepared by dissolving it in fluorobenzene (FB) to obtain a 5% (w / w) solution. 60 Saturated solution.

[0081] Example 4 The preparation method in this embodiment is basically the same as that in Example 1, except that: a certain amount of C is weighed. 60 FB-C was prepared by dissolving it in fluorobenzene (FB) to obtain a mass fraction of 0.5%. 60 Saturated solution.

[0082] Example 5 The preparation method in this embodiment is basically the same as that in Example 1, except that: a certain amount of C is weighed. 60 FB-C was prepared by dissolving it in fluorobenzene (FB) to obtain a 7% (w / w) solution. 60 Saturated solution.

[0083] Example 6 The preparation method of this embodiment is basically the same as that of Example 1, except that the second additive is tris(trimethylsilyl)borate.

[0084] Example 7 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 4.61 wt%, the mass ratio of the second additive in the electrolyte is 1.39 wt%, and the mass ratio of the first additive to the second additive is 1:0.3.

[0085] Example 8 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 2 wt%, the mass ratio of the second additive in the electrolyte is 4 wt%, and the mass ratio of the first additive to the second additive is 1:2.

[0086] Example 9 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 1 wt%, the mass ratio of the second additive in the electrolyte is 5 wt%, and the mass ratio of the first additive to the second additive is 1:5.

[0087] Example 10 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 0.375 wt%, the mass ratio of the second additive in the electrolyte is 5.325 wt%, and the mass ratio of the first additive to the second additive is 1:15.

[0088] Example 11 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 0.1935 wt%, the mass ratio of the second additive in the electrolyte is 5.805 wt%, and the mass ratio of the first additive to the second additive is 1:30.

[0089] Example 12 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 16 wt%, the mass ratio of the second additive in the electrolyte is 4 wt%, and the mass ratio of the first additive to the second additive is 1:0.25.

[0090] Example 13 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 0.6 wt%, the mass ratio of the second additive in the electrolyte is 30 wt%, and the mass ratio of the first additive to the second additive is 1:50.

[0091] Example 14 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 0.1 wt%, the mass ratio of the second additive in the electrolyte is 1.22 wt%, and the mass ratio of the first additive to the second additive is 1:12.2.

[0092] Example 15 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 5 wt%, the mass ratio of the second additive in the electrolyte is 1.9 wt%, and the mass ratio of the first additive to the second additive is 1:2.6.

[0093] Example 16 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 0.05 wt%, the mass ratio of the second additive in the electrolyte is 0.05 wt%, and the mass ratio of the first additive to the second additive is 1:1.

[0094] Example 17 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 6 wt%, the mass ratio of the second additive in the electrolyte is 6 wt%, and the mass ratio of the first additive to the second additive is 1:1.

[0095] Example 18 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 3.46 wt%, the mass ratio of the second additive in the electrolyte is 3.46 wt%, and the ratio of the nickel content in the positive electrode active material to the total mass of the two additives is 1.3.

[0096] Example 19 The preparation method of this embodiment is basically the same as that of Example 1, except that: the mass ratio of the first additive in the electrolyte is 1.5wt%, the mass ratio of the second additive in the electrolyte is 1.5wt%, and the ratio of the nickel content in the positive electrode active material to the total mass of the two additives is 3.

[0097] Example 20 The preparation method of this embodiment is basically the same as that of Example 1, except that: the mass ratio of the first additive in the electrolyte is 0.22wt%, the mass ratio of the second additive in the electrolyte is 1.1wt%, the mass ratio of the first additive to the second additive is 1:5, and the ratio of the nickel content in the positive electrode active material to the total mass of the two additives is 6.8.

[0098] Example 21 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 4.5 wt%, the mass ratio of the second additive in the electrolyte is 4.5 wt%, and the ratio of the nickel content in the positive electrode active material to the total mass of the two additives is 1.

[0099] Example 22 The preparation method of this embodiment is basically the same as that of Example 1, except that the mass ratio of the first additive in the electrolyte is 0.64wt%, the mass ratio of the second additive in the electrolyte is 0.64wt%, and the ratio of the nickel content in the positive electrode active material to the total mass of the two additives is 7.

[0100] Comparative Example 1 The preparation method of this comparative example is basically the same as that of Example 1, except that the electrolyte does not contain the first additive and the second additive.

[0101] Comparative Example 2 The preparation method of this comparative example is basically the same as that of Example 1, except that the electrolyte contains only the first additive.

[0102] Comparative Example 3 The preparation method of this comparative example is basically the same as that of Example 1, except that the electrolyte contains only the second additive (tris(hexafluoroisopropyl) borate).

[0103] Comparative Example 4 The preparation method of this comparative example is basically the same as that of Example 1, except that the electrolyte contains only the second additive (tris(trimethylsilyl)borate).

[0104] The parameters of Examples 1-20 and Comparative Examples 1-4 are shown in Table 1.

[0105] Table 1

[0106] Test example: 1. Electrical performance testing: The experiment used the Wuhan Landian CT2001A battery testing system. The batteries assembled in Examples 1-22 and Comparative Examples 1-4 were placed in a 25℃ constant temperature chamber and allowed to stand for 8 hours before being tested for 1C / 1C charge-discharge cycle performance. The test voltage range was set to 2.4~4.2V (vs. Li+ / Li). The test results are shown in Table 2. The results show that: ① The trend of capacity retention is highly negatively correlated with gas production, meaning that batteries with lower gas production generally exhibit better long-cycle capacity retention. All examples with lower gas production showed significantly better capacity retention than the comparative examples. This indicates that the side reaction (gas production) effectively suppressed by the additives is one of the main causes of capacity decay. ② Optimizing the formulation improves cycle life: The capacity retention of the composite additive system (all examples) is generally better than that of the single additive system. The ratio of the two additives needs to be within a reasonable range to maintain a high capacity retention.

[0107] 2. Gas production test: Using the water displacement method, at room temperature (25℃), the batteries of the examples and comparative examples were completely immersed in deionized water before cycling and after 100, 300, and 500 cycles of 1C / 1C. The change in tension during suspension was measured using a precision balance, and the volume change was calculated according to the formula ΔV = (m1-m2) / ρ (where m1 and m2 are the mass readings corresponding to the tension before and after cycling, and ρ is the water density). This change was the amount of gas produced. Three measurements were taken, and the average value was used. The results are shown in Table 2. The test results show that: ① There is a synergistic effect between the two additives: Comparative Example 1, without any additives, had the highest gas production in all cycling cycles (e.g., 16.8 ml after 500 cycles); Comparative Examples 2-4, with only a single additive, had a lower gas production than Comparative Example 1, but it was still significantly higher than the examples using both additives (e.g., Example 1 had a gas production of only 5.3 ml after 500 cycles). This indicates that the combined use of the first and second additives has a synergistic effect of "1+1>2" in suppressing gas production. ② There is an optimal range for additive content and ratio: Additive ratio: When the total amount added is fixed, the ratio of the two additives needs to be coordinated. When the proportion of the first additive is too high or too low, the gas production will deteriorate.

[0108] To achieve both low gas production and high capacity retention simultaneously, a composite system consisting of a first additive and a second additive is required, with their total content and ratio controlled within an experimentally validated optimal window. No single additive or an unbalanced formulation can achieve the best synergistic protective effect. Table 2

[0109] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An electrolyte, characterized in that, include: The first additive comprises a fluorobenzene solution containing fullerene; The second additive is a borate ester film-forming agent, and the general structural formula of the borate ester film-forming agent is B(OR)3, where R is an organic group.

2. The electrolyte according to claim 1, characterized in that, The organic groups include C. 1-10 Alkyl, C 1-10 Haloalkyl, C 1-10 Silyl, C 2-10 At least one of alkenyl, polyethylene glycol residue, 3-7 membered cycloalkyl, 3-7 membered heterocycloalkyl, 3-7 membered aryl, and 3-7 membered heteroaryl; And / or, based on the total mass of the fullerene-containing fluorobenzene solution, the mass percentage of fullerene is 1-5%; And / or, the borate ester film-forming agent includes at least one of tris(hexafluoroisopropyl) borate, tris(trimethylsilyl) borate, and polyethylene glycol borate.

3. The electrolyte according to claim 1 or 2, characterized in that, The mass ratio of the first additive to the second additive is 1:(0.3~30); And / or, the first additive accounts for 0.1% to 5% of the mass of the electrolyte; And / or, the second additive accounts for 1% to 38.5% of the mass of the electrolyte.

4. The electrolyte according to claim 3, characterized in that, Further includes lithium salts and organic solvents.

5. The electrolyte according to claim 4, characterized in that, The lithium salt includes at least one of inorganic lithium salt and organic lithium salt; And / or, the concentration of the lithium salt in the electrolyte is 1~4 mol / L; And / or, the organic solvent is selected from carbonate solvents; And / or, the organic solvent accounts for 60-85% of the mass of the electrolyte.

6. A battery, characterized in that, The electrolyte includes any one of claims 1 to 5.

7. The battery according to claim 6, characterized in that, Further includes: The positive electrode includes a positive active layer, and the positive active layer includes a positive active material, wherein the positive active material is LiMn. x Fe 1-x PO4-LiNi a Co b Mn 1-a-b O2, where 0.5 ≤ x < 1; 0.8 ≤ a < 1, 0.1 ≤ b ≤ 0.33, LiNi a Co b Mn 1-a-b O2 and LiMn x Fe 1-x The mass ratio of PO4 is ≥0.1%.

8. The battery according to claim 7, characterized in that, The nickel content 'a' in the positive electrode active material and the mass ratio 'c' of the additive in the electrolyte satisfy the following relationship: 1.3 ≤ a : c ≤ 6.8; The additive is the first additive and the second additive in the electrolyte according to any one of claims 1 to 5.

9. A battery pack, characterized in that, It includes the electrolyte of any one of claims 1 to 5 or the battery of any one of claims 6 to 8.

10. An electrical appliance, characterized in that, It includes the electrolyte of any one of claims 1 to 5, the battery of any one of claims 6 to 8, or the battery pack of claim 9.

Images