Lithium ion battery, preparation method thereof, electrolyte and electric device

Abstract

The invention provides a lithium ion battery, a preparation method thereof, an electrolyte and an electric device. The lithium ion battery comprises an electrolyte; the electrolyte comprises an additive, and the additive comprises a compound shown in the formula (1), a phosphate additive and a sulfate additive. The electrolyte adopted by the lithium ion battery can enhance the film-forming protection and high-temperature stability of the surfaces of the positive electrode and the negative electrode through the synergistic effect of the additives, the problem that the film-forming protection of the positive electrode and the negative electrode is insufficient is solved, and the high-temperature circulation and high-temperature storage performance of the lithium ion battery is further improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a lithium-ion battery and a preparation method thereof, an electrolyte and an electrical device. Background Art

[0002] In recent years, as the application scope of lithium-ion batteries such as lithium-ion batteries has become more and more extensive, lithium-ion batteries are widely used in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields. As lithium-ion batteries have made great progress, higher requirements have been put forward for their high-temperature cycle and high-temperature storage performance. Summary of the invention

[0003] In order to achieve the above-mentioned objectives, the present application provides a lithium-ion battery and a preparation method thereof, an electrolyte and an electrical device.

[0004] A first aspect of the present application provides a lithium ion battery, comprising an electrolyte, wherein the electrolyte comprises an additive, wherein the additive comprises a compound represented by formula 1), a phosphate additive, and a sulfate additive;

[0005] 1);

[0006] wherein X1 and X2 are phosphorus, Y1 to Y4 are each independently oxygen or sulfur, L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0007] The study found that if only the compound shown in formula 1) and sulfate additives are used, although the sulfate additive can decompose and participate in the interface film formation before the compound shown in formula 1), without the phosphate additive, it cannot play a good role in stabilizing the electrolyte salt, which is not conducive to improving the high-temperature stability of the interface. Therefore, it is difficult to achieve a good repair interface film and maintain passivation effect in the later stage of battery operation using the compound shown in formula 1), and therefore it is impossible to effectively improve the high-temperature cycle and storage performance.

[0008] The electrolyte used in the above lithium-ion battery contains the above three additives at the same time, among which the sulfate additives are preferentially decomposed into film before the compound shown in formula 1), and the sulfate additives participate in the interface film formation to generate sulfates and sulfites that are more stable than carbonates, thereby improving the high-temperature stability of the interface. Phosphate additives can stabilize PF6 -Anions such as lithium salts can inhibit the hydrolysis of electrolyte salts such as lithium salts, thereby inhibiting the damage of the interface film by the acid produced by hydrolysis. In addition, phosphate additives help to form an interface film rich in inorganic components at the positive and negative electrodes, with good film formation stability, which can improve the high-temperature stability of the interface and thus improve the high-temperature performance of the battery. The compound shown in Formula 1) can repair the interface film and maintain the passivation effect in the later stage of battery operation, thereby inhibiting the side reactions between the electrode and the electrolyte. The electrolyte used in the above-mentioned lithium-ion battery can enhance the film protection and high-temperature stability of the positive and negative electrode surfaces through the synergistic effect of additives, improve the problem of insufficient film protection of the positive and negative electrodes, and enhance the high-temperature cycle and high-temperature storage performance of the battery.

[0009] In some of these embodiments, one or more of the following features are met:

[0010] (1) The mass proportion of the compound represented by formula 1) in the electrolyte is 0.1% to 10%;

[0011] (2) The mass proportion of the phosphate additive in the electrolyte is 0.01% to 2%;

[0012] (3) The mass proportion of the sulfate ester additive in the electrolyte is 0.01% to 10%.

[0013] By controlling the mass proportion of the compound represented by formula 1) in the electrolyte within the above range, the additive of the compound represented by formula 1) can play a good role in post-repairing the interface film and maintaining the passivation effect, thereby enabling the battery to have better high-temperature cycling and high-temperature storage performance.

[0014] By controlling the mass proportion of the phosphate additive in the electrolyte within the above range, the phosphate additive can play a good role in stabilizing the interface film, thereby enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0015] Controlling the mass proportion of sulfate ester additives in the electrolyte within the above range can enable the sulfate ester additives to play a good role in early film formation and improve the stability of the film formation interface, thereby enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0016] When the mass proportion of the above three types of additives in the electrolyte is within the above range, an interface film with appropriate thickness and good stability can be formed on the surface of the positive and negative electrodes, so that the battery can have better high-temperature cycle and high-temperature storage performance.

[0017] In some of these embodiments, one or more of the following features are met:

[0018] (1) The mass proportion of the compound represented by formula 1) in the electrolyte is 0.5% to 5%;

[0019] (2) The mass proportion of the phosphate additive in the electrolyte is 0.05% to 1%;

[0020] (3) The mass proportion of the sulfate ester additive in the electrolyte is 0.05% to 5%.

[0021] When the mass proportion of the above three types of additives in the electrolyte is within the above range, they can not only form an interface film with appropriate thickness and good stability on the surface of the positive and negative electrodes, but also take into account the moderate internal resistance of the battery cell without deteriorating the lithium ion transmission at the interface of the positive and negative electrodes, so that the battery can take into account better high-temperature cycle and high-temperature storage performance.

[0022] In some of the embodiments, the mass ratio of the phosphate additive to the sulfate additive is (0.02~20):1.

[0023] In some of the embodiments, the ratio of the sum of the mass of the sulfate additive and the phosphate additive to the mass of the compound represented by formula 1) is (0.1-20):1.

[0024] When the ratio of the sum of the masses of sulfate additives and phosphate additives to the mass of the compound shown in Formula 1 is further controlled to be within the above range, the compound shown in Formula 1 can repair the interface film in the later stage of battery operation to maintain the passivation effect, and the thickness of the interface film formed by controlling the additive to be moderate makes the impedance of the battery cell moderate, which is conducive to the transmission of lithium ions and at the same time helps to reduce side reactions, thereby improving the cycle life of the battery cell and enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0025] In some embodiments, the sulfate ester additive includes one or more of a cyclic sulfate ester and a chain sulfate ester. Optionally, the sulfate ester additive includes a cyclic sulfate ester. The cyclic sulfate ester has a stronger reaction activity than the chain sulfate ester, which helps it to react and form a film before the solvent, thereby improving the film-forming components, inhibiting the side reaction between the electrolyte and the negative electrode, and improving the high-temperature cycle storage performance.

[0026] In some embodiments, the cyclic sulfate includes one or more of vinyl sulfate and its derivatives.

[0027] In some embodiments, the cyclic sulfate comprises one or more of the following compounds (c-1) to (c-17):

[0028]

[0029]

[0030]

[0031] .

[0032] In some embodiments, the chain sulfate ester includes a chain sulfate ester having a carbon number of 1 to 20. The chain sulfate ester may optionally include one or more of ethyl hydrogen sulfate, dimethyl sulfate, diethyl sulfate, dipropyl sulfate, dibutyl sulfate and diisopropyl sulfate.

[0033] In some embodiments, the phosphate additive includes one or more of dihalogenated lithium phosphate and dihalogenated (bisoxalate) lithium phosphate. Optionally, the phosphate additive includes dihalogenated lithium phosphate.

[0034] Phosphate additives can stabilize PF6 in the electrolyte - Anions such as lithium salts inhibit the decomposition of electrolyte salts such as lithium salts and help form an interfacial film with good stability at the positive and negative electrodes, thereby improving the high temperature performance of the battery.

[0035] In some embodiments, the halogen in the dihalogenated lithium phosphate and the dihalogenated (bisoxalate) lithium phosphate is independently F or Cl.

[0036] Optionally, the lithium dihalophosphate includes lithium difluorophosphate.

[0037] Dihalogenated lithium phosphates include but are not limited to lithium difluorophosphate (LiPO2F2). Dihalogenated lithium phosphates such as lithium difluorophosphate decompose to form inorganic SEI containing lithium, which has a small film-forming impedance and can improve the lithium ion conductivity of the interface. In addition, since the film-forming impedance of dihalogenated lithium phosphate is small, the amount of dihalogenated lithium phosphate added can be appropriately increased to obtain a thicker interface film, thereby improving the high-temperature stability of the interface film, thereby improving the high-temperature cycle and high-temperature storage performance of lithium-ion batteries.

[0038] In some embodiments, the divalent hydrocarbon group having 1 to 10 carbon atoms and the monovalent hydrocarbon group having 1 to 20 carbon atoms are substituted with R5 or are unsubstituted;

[0039] R5 includes one or more of an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

[0040] In some embodiments, the compound represented by Formula 1) includes one or more of the compound of Formula 1a and the compound of Formula 1b:

[0041] 1a;

[0042] 1b.

[0043] The compound of formula 1a or formula 1b can stabilize the surface of the positive electrode by decomposing to form an interfacial film, and can rely on the oxygen in the structure to be adsorbed on the surface of the positive electrode to inhibit the side reaction between the positive electrode and the electrolyte to improve the life of the battery. During the charge and discharge of the battery, the compound of formula 1a or formula 1b can form a stable SEI on the surface of the negative electrode, which can improve the high-temperature cycle storage performance of the battery.

[0044] In some embodiments, the electrolyte also includes a solvent, and the solvent includes one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

[0045] In some of these embodiments, the electrolyte further comprises a lithium salt;

[0046] The lithium salt includes one or more of LiPF6, LiClO4, LiBF4, LiAsF6, LiSbF6, LiAlO2, LiAlCl4, LiN(FSO2)2, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiCl and LiI.

[0047] In some of the embodiments, the lithium-ion battery further comprises a positive electrode plate, the positive electrode plate comprises a positive electrode active material, and the positive electrode active material comprises one or more of an olivine-structured lithium-containing phosphate, a lithium transition metal oxide, and their respective modified compounds.

[0048] In some embodiments, the lithium-ion battery further comprises a negative electrode plate, the negative electrode plate comprises a negative electrode active material, the negative electrode active material comprises one or more of graphite, soft carbon, hard carbon, mesophase carbon microbeads, carbon fibers, carbon nanotubes, silicon-based materials, tin-based materials and lithium titanate.

[0049] In a second aspect of the present application, a method for preparing a lithium ion battery is also provided, comprising the following steps:

[0050] Injecting an electrolyte into the electrode assembly; the electrolyte includes an additive, and the additive includes a compound shown in Formula 1), a phosphate additive, and a sulfate additive;

[0051] 1);

[0052] wherein X1 and X2 are phosphorus, Y1 to Y4 are each independently oxygen or sulfur, L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0053] In some embodiments, the electrolyte is the electrolyte in the lithium-ion battery provided in the first aspect of the present application.

[0054] In a third aspect of the present application, an electrolyte is provided, the electrolyte comprising an additive, the additive comprising a compound represented by formula 1), a phosphate additive and a sulfate additive;

[0055] 1);

[0056] wherein X1 and X2 are phosphorus, Y1 to Y4 are each independently oxygen or sulfur, L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0057] In some embodiments, the electrolyte is the electrolyte in the lithium-ion battery provided in the first aspect of the present application.

[0058] The fourth aspect of the present application provides an electrical device, comprising at least one of the lithium-ion battery provided in the first aspect of the present application, the lithium-ion battery prepared by the preparation method provided in the second aspect of the present application, and the electrolyte provided in the third aspect of the present application.

[0059] The electric device of the present application includes the lithium-ion battery provided by the present application, and thus has at least the same advantages as the lithium-ion battery.

[0060] The details of one or more embodiments of the present application are set forth in the following drawings and description. Other features, objects, and advantages of the present application will become apparent from the description, drawings, and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] In order to better describe and illustrate the embodiments or examples provided by the present application, reference may be made to one or more drawings. The additional details or examples used to describe the drawings should not be considered as limiting the scope of the disclosed application, the embodiments or examples currently described, and any of the best modes of these applications currently understood. Moreover, the same reference numerals are used throughout the drawings to represent the same components. In the drawings:

[0062] Figure 1 FIG. 1 is a schematic diagram of a lithium-ion battery according to an embodiment of the present application.

[0063] Figure 2 yes Figure 1 An exploded view of a lithium-ion battery according to an embodiment of the present application is shown.

[0064] Figure 3 is a schematic diagram of a lithium-ion battery according to one embodiment of the present application.

[0065] Figure 4 is a schematic diagram of a lithium-ion battery according to one embodiment of the present application.

[0066] Figure 5 yes Figure 4 An exploded view of a lithium-ion battery according to an embodiment of the present application is shown.

[0067] Figure 6 Schematic diagram of an electrical device using a lithium-ion battery as a power source according to an embodiment of the present application.

[0068] Description of reference numerals:

[0069] 1. Battery pack; 2. Upper box; 3. Lower box; 4. Battery module; 5. Battery cell; 51. Shell; 52. Electrode assembly; 53. Cover plate. DETAILED DESCRIPTION

[0070] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0071] "Scope" disclosed in the present application can be limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or excluding end values, and any end value can be included or not included independently, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 listed, and if the maximum range values ​​3,4 and 5 are also listed, the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc. For example, when a parameter is expressed as an integer selected from "2-10", it is equivalent to listing the integers 2, 3, 4, 5, 6, 7, 8, 9 and 10.

[0072] In the present application, "plurality", "multiple" and the like, unless otherwise specified, refer to a number greater than or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0073] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0074] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment or implementation of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments. The "implementation methods" mentioned herein have a similar understanding.

[0075] Those skilled in the art will appreciate that, in the methods of each embodiment or example, the order in which each step is written does not mean a strict order of execution and does not constitute any limitation on the implementation process, and the detailed order of execution of each step should be determined by its function and possible internal logic. If there is no special explanation, all steps of the present application can 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 steps (b) and (a) performed sequentially. For example, the method may also include step (c), indicating that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0076] In this application, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0077] In this application, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If there are multiple "options" in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "option" is independent.

[0078] Herein, "alkyl" includes one or more of straight chain, branched chain and cyclic alkyl. The carbon number of the alkyl can be 1 to 50, 1 to 30, 1 to 20, 1 to 10 or 1 to 6. A phrase containing this term, for example, "C1~C10 alkyl" refers to an alkyl containing 1 to 10 carbon atoms, and each occurrence can be independently C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl, C9 alkyl or C10 alkyl.

[0079] Non-limiting examples of alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, isobutyl, 2-ethylbutyl, 3,3-dimethylbutyl, n-pentyl, isopentyl, neopentyl, tert-pentyl, cyclopentyl, 1-methylpentyl, 3-methylpentyl, 2-ethylpentyl, 4-methyl-2-pentyl, n-hexyl, 1-methylhexyl, 2-ethylhexyl, 2-butylhexyl, cyclohexyl, 4-methylcyclohexyl, 4-tert-butylcyclohexyl, n-heptyl, 1-methylheptyl, 2,2-dimethylheptyl, 2-ethylheptyl, 2-butylheptyl, n-octyl, tert-octyl, 2-ethyloctyl, 2-butyloctyl, 2-hexyloctyl, 3,3 ... 2-butylheptyl, 2-ethylheptyl, 2-butylheptyl, 2-butylheptyl, 2-ethylheptyl, 2-butylheptyl, 2-butylheptyl, 2-butylheptyl, 2-ethylheptyl, 2-butylheptyl, 2-butylheptyl, 2-butylheptyl, 2-ethylheptyl, 2-butylheptyl, 2-butylheptyl, 2-ethylheptyl, 2-butylheptyl, 2-butylheptyl, 2-ethylheptyl, 2-butylheptyl, 2-butyl ,7-dimethyloctyl, cyclooctyl, n-nonyl, n-decyl, adamantyl, 2-ethyldecyl, 2-butyldecyl, 2-hexyldecyl, 2-octyldecyl, n-undecyl, n-dodecyl, 2-ethyldodecyl, 2-butyldodecyl, 2-hexyldodecyl, 2-octyldodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, 2-ethylhexadecyl, 2-butylhexadecyl, 2-hexylhexadecyl, 2-octylhexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, 2-ethyleicosyl, 2-butyleicosyl, 2-hexyleicosyl, 2-octyleicosyl, n-heneicosyl, n-docosyl, n-tricosyl, n-tetracosyl, n-pentacosyl, n-hexacosyl, n-heptacosyl, n-octacosyl, n-nonacosyl, n-triacontyl, adamantane, etc.

[0080] Herein, the alkyl group in "alkoxy" has the same definition as the alkyl group in the above text. As an example, the alkoxy group includes, but is not limited to, methoxy, ethoxy, propoxy, and the like.

[0081] Herein, "halogen" includes one or more of F, Cl, Br, and I.

[0082] As used herein, "alkylene" is a divalent alkyl group which has lost one hydrogen from an alkyl group. The definition of alkyl is as defined above. As examples, alkylene includes, but is not limited to, -CH2-, -CH2CH2-, -CH2CH2CH2-, -CH2(CH2)CH-, -CH(CH2)CH2-, and -CH(CH2)CH2CH2-.

[0083] As used herein, "alkenyl" includes both straight chain and branched chain alkenyl chemical groups.

[0084] As used herein, "alkynyl" includes both straight and branched chain alkynyl chemical groups.

[0085] Herein, "aryl" refers to a hydrocarbon group with aromaticity, including monocyclic aromatic groups and condensed aromatic groups. Condensed aromatic groups refer to a group formed by connecting two or more monoaromatic rings through two common adjacent ring atoms, i.e., a condensed ring. Further: the π electrons of the aromatic group should satisfy 4n+2 (Huckel's rule). "Aryl" includes aromatic groups and heteroaromatic groups that do not contain heteroatoms. "Heteroaromatic" refers to a group in which at least one ring-forming atom is a heteroatom and has aromaticity. Heteroatoms include, but are not limited to, N, P, O, and S.

[0086] Non-limiting examples of “aromatic groups” in the present application include benzene, naphthalene, anthracene, fluoranthene, phenanthrene, triphenylene, perylene, tetracene or fluorene, etc.; non-limiting examples of “heteroaromatic groups” include pyridine, pyrimidine, pyrazine, triazine, imidazole, furan, thiophene, benzofuran, benzothiophene, indole, carbazole, pyrroloimidazole, pyrrolopyrrole, thienopyrrole, thienothiophene, furopyrrole, furanofuran, thienofuran, benzisoxazole, benzisothiazole, benzimidazole, quinoline, isoquinoline, o-naphthylidene, quinoxaline, phenanthridine, primary idine, quinazoline, quinazolinone, dibenzofuran, dibenzothiophene, carbazole, etc.; non-limiting examples of “aromatic amine groups” include substituted or unsubstituted aniline, substituted or unsubstituted diphenylamine or substituted or unsubstituted triphenylamine.

[0087] The high-temperature cycling and high-temperature storage performance of lithium-ion batteries have long been a concern in the battery field.

[0088] Based on this technical problem, the research found that the stability of the positive and negative electrode interface films of lithium-ion batteries is greatly affected at high temperatures. For example, at high temperatures, the solid electrolyte interface film (SEI film) on the surface of the negative electrode may be destroyed and reorganized. The destruction of the SEI film will cause the electrolyte to continue to react with the negative electrode, consume active lithium ions, increase internal resistance, and reduce battery capacity and cycle life.

[0089] Therefore, the present application provides a lithium-ion battery and its preparation method, electrolyte and power-consuming device. The electrolyte used in the battery can enhance the film protection and high-temperature stability of the positive and negative electrode surfaces through the synergistic effect of additives, improve the problem of insufficient film protection of the positive and negative electrodes, and thus improve the high-temperature cycle and high-temperature storage performance of the lithium-ion battery.

[0090] An embodiment of the present application provides a lithium ion battery and a method for preparing the same. The lithium ion battery includes an electrolyte. The electrolyte includes an additive, and the additive includes a compound shown in Formula 1), a phosphate additive, and a sulfate additive.

[0091] The structural formula of the compound shown in formula 1) is as follows:

[0092] 1);

[0093] Wherein, X1 and X2 are phosphorus (P), Y1 to Y4 are each independently oxygen (O) or sulfur (S), L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group, or a monovalent hydrocarbon group having 1 to 20 carbon atoms. When L is a single bond, it means that Y1 and Y4 are directly bonded through a single bond.

[0094] Further, the divalent hydrocarbon group having 1 to 10 carbon atoms and the monovalent hydrocarbon group having 1 to 20 carbon atoms are substituted or unsubstituted. Further, the substituent is denoted as R5, and R5 includes a group consisting of one or more of an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

[0095] Furthermore, L is a substituted or unsubstituted alkylene group having 1 to 10 carbon atoms.

[0096] Furthermore, R1 to R4 are each independently a halogen atom, or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0097] Furthermore, R1 to R4 are halogen atoms, and R1 to R4 are each independently one of F, Cl, Br, and I. Furthermore, R1 to R4 may be the same or different, and further all are F.

[0098] Furthermore, L is a substituted or unsubstituted alkylene group having 1 to 5 carbon atoms.

[0099] The electrolyte used in the above lithium-ion battery contains the above three additives at the same time, among which the sulfate additives are preferentially decomposed into film before the compound shown in formula 1), and the sulfate additives participate in the interface film formation to generate sulfates and sulfites that are more stable than carbonates, thereby improving the high-temperature stability of the interface. Phosphate additives can stabilize PF6 - Anions inhibit the hydrolysis of electrolyte salts such as lithium salts, thereby inhibiting the damage of the interface film by the acid produced by hydrolysis. In addition, phosphate additives help to form an interface film rich in inorganic components at the positive and negative electrodes, with good film formation stability, which can improve the high-temperature stability of the interface and thus improve the high-temperature performance of the battery. The compound shown in Formula 1) can repair the interface film and maintain the passivation effect in the later stage of battery operation, thereby inhibiting the side reactions between the electrode and the electrolyte. The electrolyte used in the above-mentioned lithium-ion battery can enhance the film protection and high-temperature stability of the positive and negative electrode surfaces through the synergistic effect of additives, improve the problem of insufficient film protection of the positive and negative electrodes, and enhance the high-temperature cycle and high-temperature storage performance of the battery.

[0100] In some of the embodiments, the mass proportion of the compound represented by Formula 1) in the electrolyte is 0.1% to 10%. Controlling the mass proportion of the compound represented by Formula 1) in the electrolyte within the above range can enable the additive of the compound represented by Formula 1) to play a good post-repair interface film maintenance passivation effect, thereby enabling the battery to have better high-temperature cycle and high-temperature storage performance. As an example, the mass proportion of the compound represented by Formula 1) in the electrolyte can be 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or within the range consisting of any two of the above point values ​​as end values, optionally 0.1% to 5%, more optionally 0.5% to 5%, or optionally 2% to 3%. By controlling the mass proportion of the compound represented by formula 1) in the electrolyte to be within the above range, the additive of the compound represented by formula 1) can play a good role in maintaining the passivation effect of the post-repair interface film, while also taking into account a moderate internal resistance of the battery cell, without deteriorating the lithium ion transmission at the positive and negative electrode interfaces, thereby enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0101] In some embodiments, the mass proportion of phosphate additives in the electrolyte is 0.01% to 2%. Controlling the mass proportion of phosphate additives in the electrolyte within the above range can make the phosphate additives play a good role in stabilizing the interface film, so that the battery can take into account better high-temperature cycle and high-temperature storage performance. As an example, the mass proportion of phosphate additives in the electrolyte can be 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, or any two of the above points as the end value The range is optionally 0.05% to 2%, and more optionally 0.05% to 1%. Controlling the mass proportion of phosphate additives in the electrolyte within the above range can make the phosphate additives play a good role in stabilizing the interface film, and can also take into account the moderate internal resistance of the battery cell, without deteriorating the lithium ion transmission at the positive and negative electrode interfaces, so that the battery can take into account better high-temperature cycle and high-temperature storage performance.

[0102] In some of the embodiments, the mass proportion of sulfate ester additives in the electrolyte is 0.01% to 10%. Controlling the mass proportion of sulfate ester additives in the electrolyte within the above range can make the sulfate ester additives play a good role in early film formation and improve the stability of the film formation interface, so that the battery can take into account better high-temperature cycle and high-temperature storage performance. As an example, the mass proportion of sulfate ester additives in the electrolyte can be 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any two of the above points as the end value range, optionally 0.05% to 10%, more optionally 0.05% to 5%, or optionally 0.05% to 3%. Controlling the mass proportion of sulfate ester additives in the electrolyte within the above range can enable the sulfate ester additives to play a good role in early film formation and improve the stability of the film formation interface, while also taking into account a moderate internal resistance of the battery cell and not deteriorating the lithium ion transmission at the positive and negative electrode interfaces, thereby enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0103] When the mass proportion of the above three types of additives in the electrolyte is within the above range, an interface film with suitable thickness and good stability can be formed on the surface of the positive and negative electrodes, so that the battery can have better high-temperature cycle and high-temperature storage performance. Furthermore, it can also take into account the moderate internal resistance of the battery cell and not deteriorate the lithium ion transmission at the interface of the positive and negative electrodes, so that the battery can have better high-temperature cycle and high-temperature storage performance.

[0104] In some embodiments, the mass ratio of the phosphate additive to the sulfate additive is (0.02-20): 1, and can be (0.05-16): 1. As an example, the mass ratio can be 0.02: 1, 0.05: 1, 0.08: 1, 0.1: 1, 0.16: 1, 0.2: 1, 0.5: 1, 0.8: 1, 1: 1, 2: 1, 5: 1, 8: 1, 10: 1, 12: 1, 14: 1, 15: 1, 16: 1, 18: 1, 20: 1, or any value within the range formed by any two of the above point values ​​as end values. By further controlling the mass ratio of sulfate additives and phosphate additives within the above range, the two can exert a better synergistic effect. Sulfate additives form a more stable interface film by preferentially forming a film and optimizing the film-forming components. Phosphate additives inhibit the hydrolysis of lithium salts and alleviate the damage of hydrolysis and acid production to the interface film, thereby synergistically strengthening film protection, thereby enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0105] In some embodiments, the ratio of the sum of the mass of the sulfate additive and the phosphate additive to the mass of the compound represented by formula 1) is (0.1-20):1, and can be (0.1-18):1. As an example, the mass ratio can be 0.1:1, 0.18:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.7:1, 0.8:1, 1:1, 2:1, 3:1, 4:1, 5:1, 8:1, 10:1, 12:1, 14:1, 15:1, 16:1, 18:1, 20:1, or any value within the range formed by any two of the above point values ​​as end values. When the ratio of the sum of the masses of sulfate additives and phosphate additives to the mass of the compound shown in Formula 1 is further controlled to be within the above range, the compound shown in Formula 1 can repair the interface film in the later stage of battery operation to maintain the passivation effect, and the thickness of the interface film formed by controlling the additive to be moderate makes the impedance of the battery cell moderate, which is conducive to the transmission of lithium ions and at the same time helps to reduce side reactions, thereby improving the cycle life of the battery cell and enabling the battery to have better high-temperature cycle and high-temperature storage performance.

[0106] In some embodiments, the sulfate ester additive includes one or more of cyclic sulfate esters and chain sulfate esters.

[0107] Furthermore, the chain sulfate includes chain sulfates having 1 to 20 carbon atoms, including but not limited to one or more of ethyl hydrogen sulfate, dimethyl sulfate, diethyl sulfate, dipropyl sulfate, dibutyl sulfate and diisopropyl sulfate.

[0108] Optionally, the sulfate ester additive includes a cyclic sulfate ester. The cyclic sulfate ester has a stronger reactivity than the chain sulfate ester, which is more conducive to reacting to form a film before the solvent, thereby improving the film-forming components, inhibiting the side reaction between the electrolyte and the negative electrode, and improving the high-temperature cycle storage performance.

[0109] In some embodiments, the cyclic sulfate includes one or more of dithiothioate (DTD) and its derivatives. The structural formula of dithiothioate (DTD) is as follows:

[0110] .

[0111] Further, the derivative of vinyl sulfate includes vinyl sulfate substituted with a substituent. The substituent is denoted as R6. It can be understood that the substituent replaces H (hydrogen atom) in vinyl sulfate. Further, the substituent R6 may be one or more, and when there are multiple substituents, they may be the same or different; further, the substituent may be one or two, and the two substituents R6 are respectively connected to two adjacent carbon atoms of vinyl sulfate.

[0112] Further, the substituent R6 independently includes alkyl, alkoxy, halogen, , cyano (-CN) or a combination of one or more. It is attached to the carbon of the vinyl sulfate through a carbon atom in the ring.

[0113] Optionally, diethyl sulfate (DTD) and its derivatives include one or more of the following compounds (c-1) to (c-17):

[0114]

[0115]

[0116]

[0117] .

[0118] In some embodiments, the phosphate additive includes one or more of dihalogenated lithium phosphate and dihalogenated (bis(oxalate)) lithium phosphate. Phosphate additives can stabilize PF6 - Anions such as lithium salts inhibit the decomposition of electrolyte salts such as lithium salts and help form an interfacial film with good stability at the positive and negative electrodes, thereby improving the high temperature performance of the battery.

[0119] The halogen and alkyl in the halogenated group in the phosphate additive have the same definitions as above. Further, the halogen in the dihalogenated lithium phosphate and the dihalogenated (bisoxalate) lithium phosphate is independently F or Cl.

[0120] Optionally, the phosphate additive includes dihalogenated lithium phosphate. Dihalogenated lithium phosphates include but are not limited to lithium difluorophosphate (LiPO2F2). Dihalogenated lithium phosphates such as lithium difluorophosphate decompose to form an inorganic SEI containing lithium, which has a small film-forming impedance and can improve the lithium ion conductivity of the interface. In addition, since the film-forming impedance of dihalogenated lithium phosphate is small, the amount of dihalogenated lithium phosphate added can be appropriately increased to obtain a thicker interface film, thereby improving the high-temperature stability of the interface film, thereby improving the high-temperature cycle and high-temperature storage performance of lithium-ion batteries.

[0121] Furthermore, the dihalogenated (bisoxalate) lithium phosphate includes but is not limited to difluorobisoxalate lithium phosphate (C4F2LiO8P).

[0122] In some embodiments, the compound represented by Formula 1) includes one or more of the compound of Formula 1a and the compound of Formula 1b:

[0123] 1a;

[0124] 1b.

[0125] The compound of formula 1a or formula 1b can stabilize the surface of the positive electrode by decomposing to form an interfacial film, and can rely on the oxygen in the structure to be adsorbed on the surface of the positive electrode to inhibit the side reaction between the positive electrode and the electrolyte to improve the life of the battery. During the charge and discharge of the battery, the compound of formula 1a or formula 1b can form a stable SEI on the surface of the negative electrode, which can improve the high-temperature cycle storage performance of the battery.

[0126] In some embodiments, the electrolyte further includes a solvent, and the solvent includes one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), cyclopentane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and diethyl sulfone (ESE).

[0127] In some embodiments, the electrolyte further comprises a lithium salt. Further, the lithium salt comprises one or more of lithium hexafluorophosphate (LiPF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium hexafluoroantimonate (LiSbF6), lithium aluminate (LiAlO2), lithium tetrachloroaluminate (LiAlCl4), lithium bis(fluorosulfonyl)imide (LiN(FSO2)2), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), lithium bis(pentafluoroethylsulfonyl)imide (LiN(C2F5SO2)2), LiC(CF3SO2)3, lithium chloride (LiCl) and lithium iodide (LiI).

[0128] Further, the lithium salt concentration of the electrolyte is 0.8 mol / L to 2 mol / L. As an example, the lithium salt concentration of the electrolyte may be 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.2 mol / L, 1.5 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, or within a range consisting of any two of the above point values ​​as end values.

[0129] On the other hand, the present application also provides a method for preparing a lithium-ion battery, which comprises the following steps: injecting an electrolyte into an electrode assembly.

[0130] The electrolyte has the same technical features as above and will not be described in detail here.

[0131] It is worth noting that during the formation and charge-discharge cycle of lithium-ion batteries, the lithium salts, additives, etc. in the electrolyte may gradually react and be consumed and change, for example, the composition or content may change.

[0132] Furthermore, the preparation method further comprises the steps of packaging and forming the electrode assembly after the electrolyte is injected. The aforementioned lithium-ion battery may also be a formed lithium-ion battery. The aforementioned lithium-ion battery may also be a battery that has been injected with the electrolyte but not formed.

[0133] Furthermore, in some examples, in the lithium-ion battery after formation: in its electrolyte, the mass content of the compound represented by formula 1) is 0.1%~2.5%; as an example, it can be 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, or within the range formed by any two of the above point values ​​as end values.

[0134] Furthermore, in some examples, in the lithium-ion battery after formation: the mass content of the phosphate additive in the electrolyte is 0.01%~0.5%; as an example, it can be 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, or within the range formed by any two of the above point values ​​as end values.

[0135] Furthermore, in some examples, in the lithium-ion battery after formation: the mass content of the sulfate ester additive in the electrolyte is 0.01%~2.5%; as an example, it can be 0.01%, 0.02%, 0.05%, 0.1%, 0.2%, 0.5%, 1%, 1.5%, 2%, 2.5%, or within the range consisting of any two of the above point values ​​as end values.

[0136] In some embodiments, the electrode assembly includes a positive electrode sheet and a negative electrode sheet, the positive electrode sheet and the negative electrode sheet are arranged opposite to each other, and the positive electrode sheet and the negative electrode sheet are immersed in the above-mentioned electrolyte. Further, the electrode assembly also includes a separator, which is arranged between the positive electrode sheet and the negative electrode sheet.

[0137] Furthermore, the positive electrode sheet, the negative electrode sheet and the separator can be made into an electrode assembly through a winding process or a lamination process.

[0138] On the other hand, the present application also provides an electrolyte, which is the electrolyte in the above preparation method or lithium ion battery.

[0139] On the other hand, the present application also provides an electrical device, comprising a lithium-ion battery prepared by the above preparation method, the above lithium-ion battery and at least one of the above electrolytes.

[0140] The lithium-ion battery and the electrical device of the present application will be described below with reference to the accompanying drawings as appropriate.

[0141] Generally, lithium-ion batteries include a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting ions between the positive electrode sheet and the negative electrode sheet. The separator is set between the positive electrode sheet and the negative electrode sheet, mainly to prevent the positive and negative electrodes from short-circuiting, while allowing ions to pass through.

[0142] Herein, the electrolyte in the lithium-ion battery adopts the above-mentioned electrolyte.

[0143] Positive electrode

[0144] The positive electrode sheet includes a positive electrode current collector and a positive electrode film layer disposed on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material.

[0145] As a non-limiting example, the positive electrode current collector has two surfaces opposite to each other in its thickness direction, and the positive electrode active material layer is disposed on any one or both of the two opposite surfaces of the positive electrode current collector.

[0146] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. For example, aluminum foil may be used as the metal foil. The composite current collector may include a polymer material base layer and a metal layer formed on at least one surface of the polymer material base layer. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the positive electrode current collector, non-limiting examples of the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the positive electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0147] In some of the embodiments, the positive electrode active material may be a positive electrode active material for a battery known in the art. As a non-limiting example, the positive electrode active material may include one or more of the following materials: lithium-containing phosphates with an olivine structure, lithium transition metal oxides, and their respective modified compounds. However, the present application is not limited to these materials, and other traditional materials that can be used as positive electrode active materials for batteries may also be used. These positive electrode active materials may be used alone or in combination of two or more. Among them, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide (such as LiCoO2), lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Non-limiting examples of lithium-containing phosphates with an olivine structure may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon. Among them, the composite materials of lithium iron phosphate and carbon, the composite materials of lithium manganese phosphate and carbon, and the composite materials of lithium manganese iron phosphate and carbon include but are not limited to carbon coatings, such as carbon-coated lithium iron phosphate, carbon-coated lithium manganese phosphate and carbon-coated lithium manganese iron phosphate.

[0148] Non-limiting examples of lithium cobalt oxides may include LiCoO2; non-limiting examples of lithium nickel oxides may include LiNiO2; non-limiting examples of lithium manganese oxides may include LiMnO2, LiMn2O4, etc.; non-limiting examples of lithium nickel cobalt manganese oxides may include LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (also referred to as NCM 333 )、LiNi 0.5 Co 0.2 Mn 0.3 O2 (also referred to as NCM 523 )、LiNi 0.5 Co 0.25 Mn 0.25 O2 (also referred to as NCM 211 )、LiNi 0.6 Co 0.2 Mn 0.2 O2 (also referred to as NCM 622 )、LiNi 0.8 Co 0.1 Mn 0.1 O2 (also referred to as NCM 811 ) etc. Non-limiting examples of lithium nickel cobalt aluminum oxide may include LiNi 0.8 Co 0.15 Al 0.05 O2.

[0149] It is understandable that the battery will be accompanied by lithium (Li) deintercalation and consumption during the charging and discharging process, and the content of Li in the positive electrode active material is different when the battery is discharged to different states. In the enumeration of positive electrode active materials in this application, unless otherwise specified, the content of Li is the initial state of the material. The positive electrode active material is applied to the positive electrode plate in the battery system, and after the charge and discharge cycle, the content of Li in the positive electrode active material contained in the plate usually changes. Among them, the content of Li can be measured by molar content, but is not limited to this. Regarding "the content of Li is the initial state of the material", the initial state of the material refers to the state before the material is added to the positive electrode slurry. It is understandable that the new material obtained by appropriate modification on the basis of the listed positive electrode active materials is also within the scope of positive electrode active materials. The aforementioned appropriate modification refers to the acceptable modification method for the positive electrode active material, and non-limiting examples include coating modification.

[0150] In the list of positive electrode active materials in this application, the content of oxygen (O) is only a theoretical state value. The release of oxygen from the lattice will cause the molar content of oxygen to change, and the actual content of O will fluctuate. Among them, the content of O can be measured by molar content, but is not limited to this.

[0151] In some embodiments, the positive electrode active material layer may further include a binder. As non-limiting examples, the binder may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin.

[0152] In some embodiments, the positive electrode active material layer may further include a conductive agent. As non-limiting examples, the conductive agent may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0153] In some of the embodiments, in the positive electrode active material layer, the mass content of the positive electrode active material is 75% to 98%.

[0154] In some of the embodiments, in the positive electrode active material layer, the mass content of the conductive agent is 0.1% to 15%, and can be optionally 0.5% to 5%.

[0155] In some of the embodiments, in the positive electrode active material layer, the mass content of the binder is 0.5% to 15%, and can be optionally 0.5% to 5%.

[0156] In some of the embodiments, the positive electrode sheet can be prepared in the following manner: the components for preparing the positive electrode sheet, such as the positive electrode active material, the conductive agent, the binder and any other components, are dispersed in a solvent to form a positive electrode slurry; the positive electrode slurry is coated on at least one side of the positive electrode collector, and after drying, cold pressing and other processes, the positive electrode sheet can be obtained. The type of solvent can be selected from but not limited to any one of the aforementioned embodiments, such as N-methylpyrrolidone (NMP). The surface of the positive electrode collector coated with the positive electrode slurry can be on a single surface of the positive electrode collector or on both surfaces of the positive electrode collector.

[0157] Negative electrode

[0158] The negative electrode plate includes a negative electrode current collector. Further, the negative electrode plate may also include a negative electrode active material layer disposed on at least one surface of the negative electrode current collector, wherein the negative electrode active material layer includes a negative electrode active material.

[0159] As a non-limiting example, the negative electrode current collector has two surfaces opposite to each other in its own thickness direction, and the negative electrode active material layer is disposed on any one or both of the two opposite surfaces of the negative electrode current collector.

[0160] In some of the embodiments, 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 base layer and a metal layer formed on at least one surface of the polymer material substrate. The composite current collector may be obtained by forming a metal material on a polymer material substrate. In the negative electrode current collector, non-limiting examples of the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy. In the negative electrode current collector, non-limiting examples of the polymer material substrate may include one or more of substrates such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.

[0161] In some of the embodiments, the negative electrode active material may adopt the negative electrode active material for batteries known in the art. As a non-limiting example, the negative electrode active material may include one or more of the following materials: graphite, soft carbon, hard carbon, mesophase carbon microspheres, carbon fibers, carbon nanotubes, silicon-based materials, tin-based materials, lithium titanate, etc. Graphite includes but is not limited to one or more of artificial graphite and natural graphite. Silicon-based materials may include one or more of elemental silicon, silicon oxide compounds, silicon-carbon composites, silicon-nitrogen composites, and silicon alloys. Tin-based materials may include one or more of elemental tin, tin oxide compounds, and tin alloys. However, the present application is not limited to these materials, and other traditional materials that can be used as negative electrode active materials for batteries may also be used. These negative electrode active materials may be used alone or in combination of two or more.

[0162] In some embodiments, the negative electrode active material layer may further include a binder. The binder may include one or more 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).

[0163] In some embodiments, the negative electrode active material layer may further include a conductive agent, which may include one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0164] In some of the embodiments, the negative electrode active material layer may further include other additives, such as a thickener (eg, sodium carboxymethyl cellulose (CMC-Na)).

[0165] In some of the embodiments, in the negative electrode active material layer, the mass content of the negative electrode active material is 75% to 98%.

[0166] In some of the embodiments, in the negative electrode active material layer, the mass content of the conductive agent is 0.1% to 15%, and can be optionally 0.5% to 5%.

[0167] In some of the embodiments, in the negative electrode active material layer, the mass content of the binder is 0.5% to 15%, and can be optionally 0.5% to 5%.

[0168] In some of the embodiments, in the negative electrode active material layer, the mass content of the thickener is 0.1% to 15%, and can be optionally 0.5% to 5%.

[0169] In some embodiments, the negative electrode sheet can be prepared by the following method: the components for preparing the negative electrode sheet, such as the negative electrode active material, the conductive agent, the binder and any other components are dispersed in a solvent (a non-limiting example of the solvent is deionized water) to form a negative electrode slurry; the negative electrode slurry is coated on at least one side of the negative electrode current collector, and after drying, cold pressing and other processes, the negative electrode sheet can be obtained. The surface of the negative electrode current collector coated with the negative electrode slurry can be on a single surface of the negative electrode current collector or on both surfaces of the negative electrode current collector.

[0170] Isolation film

[0171] In some embodiments, the lithium-ion battery further includes a separator. The present application has no particular limitation on the type of separator, and any known porous separator with good chemical stability and mechanical stability can be selected.

[0172] In some embodiments, the material of the isolation membrane may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene and polyvinylidene fluoride. The isolation membrane may be a single-layer film or a multi-layer composite film, without particular limitation. When the isolation membrane is a multi-layer composite film, the materials of each layer may be the same or different, without particular limitation.

[0173] In some embodiments, the isolation film has a thickness of 6 μm to 40 μm, and may be 12 μm to 20 μm.

[0174] In some of the embodiments, the positive electrode sheet, the negative electrode sheet and the separator can be formed into an electrode assembly by a winding process or a lamination process.

[0175] In some embodiments, the lithium-ion battery may include an outer packaging that can be used to encapsulate the electrode assembly and the electrolyte.

[0176] In some embodiments, the outer packaging of the lithium-ion battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging of the lithium-ion battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0177] A lithium-ion battery includes at least one battery cell. A lithium-ion battery may include one or more battery cells.

[0178] In this application, unless otherwise specified, "battery cell" refers to a basic unit that can realize the mutual conversion of chemical energy and electrical energy, and further, generally speaking, at least includes a positive electrode sheet, a negative electrode sheet and an electrolyte. During the battery charging and discharging process, active ions are embedded and released back and forth between the positive electrode sheet and the negative electrode sheet. The electrolyte plays the role of conducting active ions between the positive electrode sheet and the negative electrode sheet.

[0179] The present application has no particular limitation on the shape of the battery cell, which may be cylindrical, square or any other shape. Figure 1 The lithium-ion battery shown is a battery cell, which is an example of a battery cell with an exemplary square structure.

[0180] In some embodiments, the lithium-ion battery may include an outer package. The outer package may be used to encapsulate the electrode assembly and the electrolyte. In some embodiments, the outer package of the lithium-ion battery may be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer package of the lithium-ion battery may also be a soft package, such as a bag-type soft package. The material of the soft package may be plastic, and further, non-limiting examples of plastic may include one or more of polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0181] In some of these embodiments, reference Figure 2 , the outer packaging may include a shell 51 and a cover plate 53. Among them, the shell 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity. The shell 51 has an opening connected to the receiving cavity, and the cover plate 53 can be covered on the opening to close the receiving cavity. The positive electrode sheet, the negative electrode sheet and the isolation membrane can form an electrode assembly 52 through a winding process or a lamination process. The electrode assembly 52 is encapsulated in the receiving cavity. The electrolyte is infiltrated in the electrode assembly 52. ​​The number of electrode assemblies 52 contained in the battery cell 5 can be one or more, and those skilled in the art can select according to actual needs.

[0182] In some embodiments, the lithium-ion battery may be a battery module or a battery pack. The battery module includes at least one battery cell. The number of battery cells contained in the battery module may be one or more, and those skilled in the art may select a suitable number according to the application and capacity of the battery module.

[0183] Figure 3 4 is an example of a battery module. Figure 3 In the battery module 4, the plurality of battery cells 5 may be arranged in sequence along the length direction of the battery module 4. Of course, they may also be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0184] Optionally, the battery module 4 may further include a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0185] In some of the embodiments, the battery modules may be assembled into a battery pack. The battery pack may contain one or more battery modules. Those skilled in the art may select a suitable number according to the application and capacity of the battery pack.

[0186] Figure 4 and Figure 5 1 is a battery pack 1 as an example. Figure 4 and Figure 5 The battery pack 1 may include a battery box and a plurality of battery modules 4 disposed in the battery box. The battery box includes an upper box body 2 and a lower box body 3. The upper box body 2 can cover the lower box body 3 and form a closed space for accommodating the battery modules 4. The plurality of battery modules 4 can be arranged in the battery box in any manner.

[0187] In some of the embodiments, a plurality of battery cells 5 may also be arranged in a battery box in any manner to directly obtain a secondary battery.

[0188] In addition, one embodiment of the present application further provides an electrical device, which includes the above-mentioned lithium-ion battery provided in the present application. The lithium-ion battery can be used as a power source for the electrical device, and can also be used as an energy storage unit for the electrical device. The electrical device may include mobile devices, electric vehicles, electric trains, ships and satellites, energy storage systems, etc., but are not limited thereto. Among them, the mobile device may be, for example, a mobile phone, a laptop computer, etc.; the electric vehicle may be, for example, a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc., but are not limited thereto.

[0189] As an electrical device, a lithium-ion battery can be selected according to its usage requirements.

[0190] Figure 6 The power consumption device 6 is taken as an example. The power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. In order to meet the power consumption device's requirements for high power and high energy density of lithium-ion batteries, a battery pack or a battery module can be used.

[0191] Another example of a device may be a mobile phone, a tablet computer, a notebook computer, etc. Such a device is usually required to be thin and light, and a lithium-ion battery may be used as a power source.

[0192] In order to make the technical problems, technical solutions and beneficial effects solved by the present application clearer, the present application will be further described in detail below in conjunction with the embodiments and drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its applications. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0193] If no specific techniques or conditions are specified in the examples, the techniques or conditions described in the literature in the field or the product instructions are used. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0194] Example 1

[0195] 1. Positive electrode sheet: The positive electrode active material LiNi 0.5 Co 0.2 Mn 0.3 O2, conductive agent acetylene black, and binder polyvinylidene fluoride are dissolved in a solvent N-methylpyrrolidone in a mass ratio of 98:1:1, and the mixture is fully stirred and mixed to prepare a positive electrode film slurry. The positive electrode film slurry is coated on the positive electrode current collector aluminum foil, and then dried, cold pressed, and cut to obtain a positive electrode sheet.

[0196] 2. Negative electrode sheet: The negative electrode active material graphite, the conductive agent acetylene black, the binder styrene butadiene rubber, and the thickener sodium carboxymethyl cellulose are fully stirred and mixed in a weight ratio of 96:1:2:1 in deionized water to obtain a negative electrode slurry, and the negative electrode slurry is then coated on a copper foil, and then dried, cold pressed, and cut to obtain a negative electrode sheet.

[0197] 3. Isolation film: Polypropylene film is used as the isolation film.

[0198] 4. Electrolyte: Ethylene carbonate (EC) and ethyl methyl carbonate (EMC) are mixed at a mass ratio of 30:70 to obtain an organic solvent. A certain amount of the additive shown in formula 1) (compound of formula 1a), phosphate additive (lithium difluorophosphate LiPO2F2) and sulfate additive (ethylene sulfate DTD) are added to the obtained organic solvent and dissolved in the mixed solvent, and fully dried LiPF6 is dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L.

[0199] Wherein, the structural formula of the compound of formula 1a is as follows:

[0200] 1a.

[0201] The structural formula of vinyl sulfate is as follows:

[0202] .

[0203] The mass contents of the additive represented by formula 1) (the compound of formula 1a), the phosphate additive (lithium difluorophosphate) and the sulfate additive (vinyl sulfate) in the electrolyte are 2.5%, 0.8% and 1% respectively.

[0204] 5. Battery assembly: stack the positive electrode sheet, separator, and negative electrode sheet in order, and obtain the battery cell after winding. Put the battery cell into the outer packaging, add the above-mentioned electrolyte, and obtain the lithium-ion battery after packaging, standing, formation, aging and other processes.

[0205] The following is a performance test.

[0206] (1) Battery high temperature cycle performance test: In a constant temperature environment of 45°C, the lithium-ion battery is charged at a constant current of 0.5C to a voltage of 4.4V, then charged at a constant voltage of 4.4V to a current ≤0.05C, and then the battery is discharged at a constant current of 0.5C to a voltage of 2.5V. This is a charge and discharge process, and the discharge capacity at this time is recorded as the discharge capacity of the battery in the first cycle. Repeat the charge and discharge cycles in this way, and calculate the number of cycles corresponding to the battery cycle when the capacity retention rate is 80%.

[0207] Capacity retention rate after n cycles = discharge capacity after n cycles / discharge capacity of the battery in the first cycle.

[0208] (2) Battery high temperature full charge storage performance test: In a constant temperature environment of 25°C, the battery is charged to 4.4V at a constant current of 0.33C, and then discharged to 2.5V at a constant current of 0.33C, and the discharge capacity D1 is tested; after the battery is charged to 4.4V at a constant current of 0.33C, it is placed in a constant temperature environment of 60°C for storage, and taken out for testing every 30 days. During each test, the battery is cooled to 25°C, and the battery is first charged to 4.4V at a constant current of 0.33C, and then discharged to 2.5V at a constant current of 0.33C, and the discharge capacity Dn after storage for n days is tested. The relationship curve between the storage capacity retention rate and the number of days is obtained, and the storage days at which the storage capacity retention rate is 80% are calculated (rounded to the nearest integer).

[0209] Storage capacity retention rate after storage for n days=discharge capacity Dn after storage for n days / discharge capacity D1.

[0210] (3) Impedance test: An electrochemical workstation (model: CHI660E, Shanghai Chenhua) was used to detect the impedance of the battery cell after formation. The test frequency range was 500 kHz-30 MHz, the disturbance voltage was 5 mV, and the test temperature was 25 °C.

[0211] Comparative Example 1

[0212] Comparative Example 1 is substantially the same as Example 1, except that an equal mass of carbonate (specifically fluoroethylene carbonate FEC) is used in the electrolyte of Comparative Example 1 to replace the sulfate ester additive (DTD) in Example 1.

[0213] Comparative Example 2

[0214] Comparative Example 2 is substantially the same as Example 1, except that an equal mass of sulfate additive (specifically lithium dodecyl sulfate) is used in the electrolyte of Comparative Example 1 to replace the phosphate additive (LiPO2F2) in Example 1.

[0215] Table 1

[0216]

[0217] As can be seen from Table 1, Comparative Example 1 uses fluoroethylene carbonate (FEC) to replace the sulfate additive (DTD) in Example 1, and uses the compound shown in Formula 1) and the phosphate additive LiPO2F2. Although the carbonate additive FEC can participate in the interface film formation, its film-forming interface stability is not good. The use of the phosphate additive LiPO2F2 cannot improve the high-temperature stability of its interface. The compound shown in Formula 1) is also difficult to achieve a good repair interface film to maintain passivation effect in the later stage of battery operation. Therefore, the high-temperature cycle and storage performance of Comparative Example 1 are deteriorated.

[0218] In Comparative Example 2, an equal mass of sulfate additives (specifically, lithium dodecyl sulfate) are used to replace the phosphate additive (LiPO2F2) in Example 1, and the compound represented by Formula 1) and the sulfate ester additive DTD are used at the same time. The sulfate ester additive decomposes preferentially before the compound represented by Formula 1) to participate in the interfacial film formation, while the sulfate additive lithium dodecyl sulfate cannot play a good role in stabilizing the electrolyte salt, which is not conducive to improving the high-temperature stability of the interface. Therefore, it is difficult to achieve a good repair interface film and maintain passivation effect in the later stage of battery operation using the compound represented by Formula 1). Therefore, the high-temperature cycle and storage performance of Comparative Example 2 are deteriorated.

[0219] The electrolyte in Example 1 contains the additive shown in Formula 1, phosphate additives and sulfate additives. The three additives act synergistically. Compared with carbonate additives, sulfate additives decompose into film before the compound shown in Formula 1). Participating in the interface film formation can generate sulfates and sulfites that are more stable than carbonates to improve the high-temperature stability of the interface and inhibit side reactions at the interface at high temperatures. Compared with sulfate additives, phosphate additives can stabilize PF6 in the electrolyte. -Anions inhibit the hydrolysis of lithium salts, thereby inhibiting the damage of the interface film by the acid produced by hydrolysis. In addition, phosphate additives help to form an interface film rich in inorganic components at the negative electrode, which has good film formation stability and can improve the high-temperature stability of the interface, thereby improving the high-temperature cycle and storage performance of the battery. On the basis of the above, the compound shown in formula 1) is used to achieve a good repair interface film to maintain passivation effect in the later stage of battery operation. In this way, Example 1 can enhance the film protection and high-temperature stability of the positive and negative electrode surfaces, improve the problem of insufficient film protection of the positive and negative electrodes, and enhance the high-temperature cycle and high-temperature storage performance of the battery.

[0220] Embodiments 2 to 9

[0221] It is basically the same as Example 1, except that at least one of the mass contents of the additive shown in Formula 1) (the compound of Formula 1a), the phosphate additive (lithium difluorophosphate) and the sulfate additive (vinyl sulfate) in the electrolyte is different, as shown in Table 2.

[0222] Table 2

[0223]

[0224] The electrolytes in Examples 1 to 9 all contain the additives shown in Formula 1, phosphate additives, and sulfate additives. Through the synergistic effect of the additives, the film protection and high-temperature stability of the positive and negative electrode surfaces can be enhanced, the problem of insufficient film protection of the positive and negative electrodes can be improved, and the high-temperature cycle and high-temperature storage performance of the battery can be improved.

[0225] Furthermore, the mass proportion of the compound represented by formula 1) in the electrolyte is 0.5% to 5%, the mass proportion of the phosphate additive in the electrolyte is 0.05% to 1% and / or the mass proportion of the sulfate additive in the electrolyte is 0.05% to 5%, which can form a good interface film on the surface of the positive and negative electrodes, while taking into account a moderate internal resistance of the battery cell, and basically does not deteriorate the lithium ion transmission at the interface of the positive and negative electrodes, so that the battery can obtain a better battery cycle life and storage life.

[0226] Embodiments 10 to 13

[0227] It is basically the same as Example 1, except that at least one of the types of the additives shown in Formula 1), the phosphate additives and the sulfate additives is different, and the amounts of the three additives remain unchanged, as shown in Table 3.

[0228] The structure of the compound of formula 1b is as follows:

[0229] 1b.

[0230] Table 3

[0231]

[0232] The electrolytes in Example 1 and Examples 10 to 13 all contain the additives shown in Formula 1, phosphate additives, and sulfate additives. Through the synergistic effect of the additives, the film protection and high-temperature stability of the positive and negative electrode surfaces can be enhanced, the problem of insufficient film protection of the positive and negative electrodes can be improved, and the high-temperature cycle and high-temperature storage performance of the battery can be improved.

[0233] Among them, compared with Example 1 and Example 10, compared with the use of dihalogenated (bisoxalate) lithium phosphate in Example 10, the film formation impedance of the phosphate additive of the electrolyte in Example 1 using dihalogenated lithium phosphate is smaller, so it is beneficial to obtain a thicker interface film, so as to improve the high-temperature stability of the interface film, thereby improving the high-temperature cycle and high-temperature storage performance of the lithium-ion battery and reducing the impedance of the battery.

[0234] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0235] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims, and the description and drawings may be used to interpret the scope of the claims.

Claims

1. A lithium ion battery, characterized in that: The electrolyte comprises an additive, wherein the additive comprises a compound represented by formula 1), a phosphate additive and a sulfate additive; 1）； wherein X1 and X2 are phosphorus, Y1 to Y4 are each independently oxygen or sulfur, L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

2. The lithium-ion battery according to claim 1, characterized in that Satisfy one or more of the following characteristics: (1) The mass proportion of the compound represented by formula 1) in the electrolyte is 0.1% to 10%; (2) The mass proportion of the phosphate additive in the electrolyte is 0.01% to 2%; (3) The mass proportion of the sulfate ester additive in the electrolyte is 0.01% to 10%.

3. The lithium ion battery according to claim 2, characterized in that Satisfy one or more of the following characteristics: (1) The mass proportion of the compound represented by formula 1) in the electrolyte is 0.5% to 5%; (2) The mass proportion of the phosphate additive in the electrolyte is 0.05% to 1%; (3) The mass proportion of the sulfate ester additive in the electrolyte is 0.05% to 5%.

4. The lithium ion battery according to claim 1, characterized in that The mass ratio of the phosphate additive to the sulfate additive is (0.02-20):

1.

5. The lithium ion battery according to claim 4, characterized in that The ratio of the sum of the masses of the sulfate additive and the phosphate additive to the mass of the compound represented by formula 1) is (0.1-20):

1.

6. The lithium ion battery according to any one of claims 1 to 5, characterized in that: The sulfate ester additive includes one or more of cyclic sulfate ester and chain sulfate ester.

7. The lithium ion battery according to claim 6, characterized in that The cyclic sulfate includes one or more of vinyl sulfate and its derivatives.

8. The lithium ion battery according to claim 7, characterized in that The cyclic sulfate ester includes one or more of the following compounds (c-1) to (c-17): 。 9. The lithium ion battery according to claim 6, characterized in that The chain sulfates include chain sulfates having 1 to 20 carbon atoms.

10. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The phosphate additive includes one or more of dihalogenated lithium phosphate and dihalogenated (bisoxalate) lithium phosphate.

11. The lithium ion battery according to claim 10, characterized in that The halogen in the dihalogenated lithium phosphate and the dihalogenated (bisoxalate) lithium phosphate is independently F or Cl.

12. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The divalent hydrocarbon group having 1 to 10 carbon atoms and the monovalent hydrocarbon group having 1 to 20 carbon atoms are substituted with R5 or are unsubstituted; R5 includes one or more of an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, and an aryl group having 6 to 20 carbon atoms.

13. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The compound represented by formula 1) includes one or more of the compound of formula 1a and the compound of formula 1b: 1a； 1b。 14. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The electrolyte also includes a solvent, and the solvent includes one or more of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, cyclopentane sulfone, dimethyl sulfone, methyl ethyl sulfone and diethyl sulfone.

15. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The electrolyte also includes a lithium salt; The lithium salt includes one or more of LiPF6, LiClO4, LiBF4, LiAsF6, LiSbF6, LiAlO2, LiAlCl4, LiN(FSO2)2, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiC(CF3SO2)3, LiCl and LiI.

16. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The lithium-ion battery further comprises a positive electrode sheet, wherein the positive electrode sheet comprises a positive electrode active material, wherein the positive electrode active material comprises one or more of an olivine-structured lithium-containing phosphate, a lithium transition metal oxide and their respective modified compounds.

17. The lithium ion battery according to any one of claims 1 to 5 and 7 to 9, characterized in that: The lithium-ion battery also includes a negative electrode plate, which includes a negative electrode active material, and the negative electrode active material includes one or more of graphite, soft carbon, hard carbon, mesophase carbon microspheres, carbon fibers, carbon nanotubes, silicon-based materials, tin-based materials and lithium titanate.

18. A method for preparing a lithium ion battery, characterized in that: The steps include: Injecting an electrolyte into the electrode assembly; the electrolyte includes an additive, and the additive includes a compound shown in Formula 1), a phosphate additive, and a sulfate additive; 1）； wherein X1 and X2 are phosphorus, Y1 to Y4 are each independently oxygen or sulfur, L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

19. The method for preparing a lithium ion battery according to claim 18, characterized in that: The electrolyte is the electrolyte in the lithium ion battery according to any one of claims 2 to 17.

20. An electrolyte, characterized in that: The electrolyte includes additives, and the additives include a compound shown in formula 1), a phosphate additive, and a sulfate additive; 1）； wherein X1 and X2 are phosphorus, Y1 to Y4 are each independently oxygen or sulfur, L is a single bond or a divalent hydrocarbon group having 1 to 10 carbon atoms, and R1 to R4 are each independently hydrogen, a halogen atom, a cyano group or a monovalent hydrocarbon group having 1 to 20 carbon atoms.

21. The electrolyte according to claim 20, characterized in that The electrolyte is the electrolyte in the lithium ion battery according to any one of claims 2 to 17.

22. An electrical device, characterized in that: The invention comprises at least one of the lithium ion battery according to any one of claims 1 to 17, the lithium ion battery prepared by the preparation method according to claim 18 or 19, and the electrolyte according to claim 20 or 21.

Images