Electrolyte for high voltage and lithium ion battery

Abstract

The invention relates to an electrolyte for high voltage and a lithium ion battery. The electrolyte for high voltage comprises an electrolyte salt, an organic solvent and an additive, the additive comprises a first additive, the first additive is a compound represented by the following formula (I): # imgabs0 # formula (I), and n is 0-5; and the additive accounts for 0.1-5% of the total mass of the electrolyte for the high voltage. According to the electrolyte provided by the invention, the high-temperature cycling stability of the lithium ion battery under high voltage is improved.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a high-voltage electrolyte and a lithium-ion battery. Background Art

[0002] With the widespread application of lithium-ion batteries in electric vehicles, electronic products and other fields, users have higher and higher requirements for the performance of lithium-ion batteries, especially for higher energy density. In traditional processes, increasing the charging voltage of positive electrode materials is one of the main methods to improve the energy density of lithium-ion batteries. However, increasing the charging voltage will cause instability of positive electrode active materials and electrolytes, leading to decomposition of electrolytes, which will seriously reduce the cycle stability of lithium-ion batteries.

[0003] Therefore, how to provide an electrolyte that can improve the cycle performance of batteries under high voltage has become a technical problem that needs to be solved urgently. Summary of the invention

[0004] Based on the above technical problems, the present application provides a high voltage electrolyte and a lithium ion battery. The electrolyte can improve the high temperature cycle stability of the lithium ion battery under high voltage, so that the lithium ion battery can work stably at a high voltage above 4.3V.

[0005] The first aspect of the present application provides a high voltage electrolyte, comprising an electrolyte salt, an organic solvent and an additive, wherein the additive comprises a first additive, and the first additive is a compound represented by the following formula (I):

[0006]

[0007] Formula (I),

[0008] Where n is 0~5;

[0009] The first additive accounts for 0.1% to 5% of the total mass of the high voltage electrolyte.

[0010] In some embodiments, the additive further includes a second additive, and the second additive includes at least one of a sultone compound, a cyclic sulfate ester compound, a phosphate ester compound, and a borate ester compound.

[0011] In some embodiments, the second additive accounts for 1% to 10% of the total mass of the high-voltage electrolyte.

[0012] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, and lithium bis(trifluoromethanesulfonyl)imide.

[0013] In some embodiments, the electrolyte salt accounts for 0.5% to 20% of the total mass of the high voltage electrolyte.

[0014] In some embodiments, the organic solvent includes a carbonate compound and / or a carboxylate compound.

[0015] In some embodiments, the organic solvent accounts for 1% to 90% of the total mass of the high voltage electrolyte.

[0016] In some embodiments, the carbonate compound includes at least one of fluoroethylene carbonate, difluoropropylene carbonate, trifluoroethyl methyl carbonate, trifluoromethylethylene carbonate, 4-trifluoromethylethylene carbonate, chloroethylene carbonate, di(2,2,2-trifluoroethyl) carbonate or 1,1,1,3,3,3-hexafluoroisopropyl acrylate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0017] In some embodiments, the carboxylate compound includes at least one of propyl fluorobutyrate, propyl fluoroacetate, ethyl fluoroacetate, isopropyl fluoroacetate, butyl fluoropropionate, isopropyl fluoropropionate, ethyl fluorobutyrate, methyl fluoropropionate, ethyl fluoropropionate, propyl fluoropropionate, ethyl acetate, methyl acetate, propyl butyrate, propyl acetate, isopropyl acetate, butyl propionate, isopropyl propionate, ethyl butyrate, methyl propionate, ethyl propionate, and propyl propionate.

[0018] The second aspect of the present application provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte is the high-voltage electrolyte provided in the first aspect.

[0019] In some embodiments, the positive electrode includes a positive electrode material, and the positive electrode material includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel manganese oxide, lithium-rich manganese-based materials, lithium vanadium phosphate, and a ternary material.

[0020] The present application adds an appropriate amount of a compound of the structure of formula (I) to the electrolyte. The compound of the structure has a good solvation effect with lithium ions, so that it can enter the solvation layer of lithium ions, which is beneficial for the compound of the structure of formula (I) to approach the electrode interface. At the interface between the positive and negative electrodes, the unsaturated groups contained in the compound of the structure of formula (I) can form a film on the positive and negative electrodes, avoiding direct contact between the electrodes and the electrolyte, and greatly reducing the occurrence of side reactions. In addition, the trifluoromethyl group contained in the compound of the structure of formula (I) can participate in the film-forming reaction to generate an interface layer rich in lithium fluoride, ensuring that the interface layer is dense, stable and has good ion conductivity. The high-voltage electrolyte provided in the present application improves the high-temperature cycle stability of lithium-ion batteries under high voltages, allowing lithium-ion batteries to operate stably at high voltages above 4.3V. DETAILED DESCRIPTION

[0021] References to embodiments of the present application will now be provided in detail, one or more embodiments of which are described below. Each embodiment is provided as an explanation rather than a limitation of the present application. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present application without departing from the scope or spirit of the present application. For example, a feature described or described as part of one embodiment may be used in another embodiment to produce a further embodiment.

[0022] Therefore, it is intended that the present application covers such modifications and variations that fall within the scope of the appended claims and their equivalents. Other objects, features and aspects of the present application are disclosed in or are apparent from the following detailed description. It will be appreciated by those of ordinary skill in the art that this discussion is merely a description of exemplary embodiments and is not intended to limit the broader aspects of the present application.

[0023] In the present application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0024] In this application, when it comes to numerical ranges, unless otherwise specified, the above numerical ranges are deemed to be continuous and include the minimum and maximum values ​​of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0025] In this article, when referring to the unit of a data range, if there is a unit only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 100~150 nm means that the units of the left endpoint "100" and the right endpoint "150" are both nm (nanometers).

[0026] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0027] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0028] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, mentioning that the method may also include step (c) means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0029] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0030] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0031] The first aspect of the present application provides a high voltage electrolyte, comprising an electrolyte salt, an organic solvent and an additive, wherein the additive comprises a first additive, and the first additive is a compound represented by the following formula (I):

[0032]

[0033] Formula (I),

[0034] Where n is 0~5;

[0035] The first additive accounts for 0.1% to 5% of the total mass of the high voltage electrolyte.

[0036] In this application, "high voltage" refers to a potential above 4.3 V to lithium.

[0037] The present application adds an appropriate amount of a compound of the structure of formula (I) to the electrolyte. The compound of the structure has a good solvation effect with lithium ions, so that it can enter the solvation layer of lithium ions, which is beneficial for the compound of the structure of formula (I) to approach the electrode interface. At the interface between the positive and negative electrodes, the unsaturated groups contained in the compound of the structure of formula (I) can form a film on the positive and negative electrodes. In addition, the trifluoromethyl group contained in the compound of the structure of formula (I) can participate in the film-forming reaction to generate an interface layer rich in lithium fluoride, ensuring that the interface layer is dense, stable and has good ion conductivity. The above is only a possible guess about the mechanism of the present application and does not constitute a limitation on the scope of protection of the present application.

[0038] In some embodiments, the additive further includes a second additive, and the second additive includes at least one of a sultone compound, a cyclic sulfate ester compound, a phosphate ester compound, and a borate ester compound.

[0039] In some embodiments, the second additive accounts for 1% to 10% of the total mass of the high voltage electrolyte, including but not limited to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, and 10%.

[0040] The present application adds a second additive to the electrolyte, which can capture transition metal ions dissolved from the positive electrode, reduce the deposition and reduction of transition metal ions at the negative electrode, reduce the consumption of lithium ions, and thus improve the cycle performance of the lithium-ion battery.

[0041] In some embodiments, the sultone compound includes at least one of 1,3-propane sultone, 1,4-butane sultone, and propenyl-1,3-sultone.

[0042] In some embodiments, the cyclic sulfate ester compound includes at least one of vinyl sulfate, 4-methylvinyl sulfate, and propylene sulfate.

[0043] In some embodiments, the cyclic sulfate ester compound includes at least one of the compounds having the following structural formula:

[0044]

[0045] .

[0046] In some embodiments, the phosphate compound is selected from at least one of a saturated phosphate compound and an unsaturated phosphate compound. Among them, the saturated phosphate compound includes tris(trimethylsilyl)phosphate. The unsaturated phosphate compound includes at least one of the compounds shown in formula (III):

[0047]

[0048] Among them, R 41 , R 42 , R 43 are independently selected from C1-C5 saturated hydrocarbon groups, unsaturated hydrocarbon groups, halogenated hydrocarbon groups, -Si(C m H 2m+1 )3, m is a natural number from 1 to 3, and R 41 , R 42 , R 43 At least one of them is an unsaturated hydrocarbon group.

[0049] In some embodiments, the borate compound includes at least one of tris(trimethylsilyl)borate (TMSB) and tris(triethylsilyl)borate.

[0050] In some embodiments, the electrolyte salt includes at least one of lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), lithium perchlorate (LiClO4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium tetrafluoroborate (LiBF4), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0051] In some embodiments, the electrolyte salt accounts for 0.5% to 20% of the total mass of the high voltage electrolyte, including but not limited to 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 12%, 14%, 16%, 18%, and 20%.

[0052] In some embodiments, the organic solvent includes a carbonate compound and / or a carboxylate compound.

[0053] In some embodiments, the organic solvent accounts for 1% to 90% of the total mass of the high voltage electrolyte, including but not limited to 1%, 20%, 40%, 60%, 80%, and 90%.

[0054] In some embodiments, the carbonate compound includes a halogenated carbonate compound and / or a non-halogenated carbonate compound.

[0055] The halogenated carbonate compounds include, but are not limited to, at least one of fluoroethylene carbonate, bisfluoropropylene carbonate, trifluoroethyl methyl carbonate, trifluoromethylethylene carbonate, 4-trifluoromethylethylene carbonate, chloroethylene carbonate, di(2,2,2-trifluoroethyl) carbonate, and 1,1,1,3,3,3-hexafluoroisopropyl acrylate.

[0056] The non-halogenated carbonate compound includes, but is not limited to, at least one of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate.

[0057] In some embodiments, the carboxylate compound includes a halogenated carboxylate compound and / or a non-halogenated carboxylate compound.

[0058] The halogenated carboxylic acid ester compound includes, but is not limited to, at least one of propyl fluorobutyrate, propyl fluoroacetate, ethyl fluoroacetate, isopropyl fluoroacetate, butyl fluoropropionate, isopropyl fluoropropionate, ethyl fluorobutyrate, methyl fluoropropionate, ethyl fluoropropionate, and propyl fluoropropionate.

[0059] The non-halogenated carboxylic acid ester compound includes, but is not limited to, at least one of ethyl acetate, methyl acetate, propyl butyrate, propyl acetate, isopropyl acetate, butyl propionate, isopropyl propionate, ethyl butyrate, methyl propionate, ethyl propionate, and propyl propionate.

[0060] The second aspect of the present application provides a lithium-ion battery, comprising a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte is the high-voltage electrolyte provided in the first aspect.

[0061] In some embodiments, the positive electrode includes a positive electrode material, a positive electrode binder, and a positive electrode conductor.

[0062] The positive electrode material includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel manganese oxide, lithium-rich manganese-based materials, lithium vanadium phosphate, and ternary materials.

[0063] It is understood that in the present application, the types of ternary materials are not particularly limited. Without violating the overall inventive concept of the present application, any known types of ternary materials can be used in the present application. The following is only exemplary, and the ternary material is selected from lithium nickel cobalt manganese oxide and lithium nickel cobalt aluminum oxide. The positive electrode binder includes but is not limited to polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene ethylene butylene styrene copolymer (SEBS), styrene butadiene styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate. It is used to bond components such as positive electrode active materials, positive electrode conductive materials, and positive electrode current collectors together.

[0064] The positive electrode conductive agent is mainly used to assist and improve the conductivity in the secondary battery, and there is no particular limitation on it in the embodiments of the present application, as long as it has conductivity without causing chemical changes. The following is only exemplary, the positive electrode conductive agent includes graphite, such as natural graphite or artificial graphite; carbon materials, such as super-P, acetylene black, Ketjen black, channel black, furnace black, lamp black and thermal black; conductive fibers, such as carbon fibers and metal fibers; conductive tubes, such as carbon nanotubes; metal powders, such as fluorocarbon powders, aluminum powders and nickel powders; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and polyphenylene derivatives.

[0065] In some embodiments, the negative electrode includes a negative electrode material, a negative electrode binder, and a negative electrode conductor.

[0066] The negative electrode material includes but is not limited to at least one of graphite, soft carbon, hard carbon, a composite material of single crystal silicon and graphite, a composite material of silicon oxide and graphite, lithium titanate, and niobium pentoxide.

[0067] The negative electrode binder includes, but is not limited to, one or more of polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), polyoxymethylene (POM), polycarbonate (PC), polyamide (PA), acrylic plastics, other polyolefins and copolymers thereof, polysulfone, polyphenylene ether (PPO), styrene-butadiene rubber (SBR) and carboxymethyl cellulose (CMC).

[0068] Negative electrode conductive agents include, but are not limited to, carbon-based materials, powdered nickel or other metal particles or conductive polymers. Carbon-based materials may include, for example, particles of carbon black, graphite, super-P, acetylene black (such as KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene) polystyrene sulfonate, and the like.

[0069] It is understood that the above examples of positive and negative electrodes are only illustrative, and any known positive electrode materials, positive electrode binders, positive electrode conductors, negative electrode materials, negative electrode binders, and negative electrode conductors can be used in the present application without violating the inventive concept of the present application. And the addition of known additives based on actual use requirements should also be considered within the scope of protection of the present application.

[0070] The separator separates the negative electrode from the positive electrode and provides a path for the movement of lithium ions. Any separator can be used without particular limitation, as long as it is a commonly used separator. It is preferred to have an excellent electrolyte moisture content and a separator with low resistance to ion movement in the electrolyte. A porous polymer film can be used, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure having two or more layers thereof. A typical porous non-woven fabric can also be used, for example, a non-woven fabric formed of glass fibers, polyethylene terephthalate fibers, etc. having a high melting point. In addition, a coated separator containing a ceramic component or a polymer material can also be used to ensure heat resistance or mechanical strength, and can be selectively used in a single-layer or multilayer structure.

[0071] It can also be understood that the method for preparing the battery is not particularly limited in the present application. Without violating the inventive concept of the present application, any known process method for preparing the battery can be applied to the present application.

[0072] The present application will be further described below with reference to specific embodiments and comparative examples.

[0073] Example 1

[0074] Preparation of electrolyte:

[0075] The electrolyte salt, organic solvent, first additive and second additive are weighed and set aside in a mass ratio of 13:83:1:3. The electrolyte salt is LiPF6. The organic solvent is a combination of fluoroethylene carbonate (FEC), ethylene carbonate (EC) and diethyl carbonate (DEC) in a ratio of 2:1:7. The first additive is a compound represented by formula (I) (n=1), and the second additive is 1,3-propane sultone (PS) and tris(trimethylsilyl) phosphate (TMSP) (the mass ratio of PS to TMSP is 2:1).

[0076] In a drying room, electrolyte salt is added to an organic solvent, and then additives are added and mixed evenly to obtain an electrolyte.

[0077] Preparation of positive electrode:

[0078] The positive electrode material lithium nickel manganese oxide, the positive electrode binder polyvinylidene fluoride (PVDF), and the positive electrode conductive agent super-P are mixed in a mass ratio of 95:2:3, and dispersed in a solvent N-methylpyrrolidone (NMP) to prepare a positive electrode slurry; the positive electrode slurry is coated on an aluminum foil and dried at 80°C to prepare a positive electrode.

[0079] Preparation of negative electrode:

[0080] The negative electrode material graphite, the negative electrode binder styrene-butadiene rubber SBR and carboxymethyl cellulose CMC, and the negative electrode conductive agent super-P are mixed in a mass ratio of 96:1:3, and dispersed in deionized water to prepare a negative electrode slurry; the negative electrode slurry is coated on a copper foil and dried at 80°C to prepare a negative electrode.

[0081] Preparation of lithium-ion batteries:

[0082] The positive electrode, negative electrode and isolation membrane are stacked into a shell, and an electrolyte is injected to prepare a lithium-ion battery.

[0083] Example 2

[0084] This embodiment is different from Embodiment 1 in that the first additive accounts for 5% of the total mass of the high-voltage electrolyte; and the organic solvent accounts for 79% of the total mass of the high-voltage electrolyte.

[0085] Example 3

[0086] This embodiment is different from Embodiment 1 in that the first additive accounts for 0.1% of the total mass of the high-voltage electrolyte; and the organic solvent accounts for 83.9% of the total mass of the high-voltage electrolyte.

[0087] Example 4

[0088] This embodiment is different from Embodiment 1 in that the first additive is a compound represented by formula (I) (n=0).

[0089] Example 5

[0090] This embodiment is different from Embodiment 1 in that the first additive is a compound represented by formula (I) (n=5).

[0091] Example 6

[0092] This embodiment is different from Embodiment 1 in that the additive includes only the first additive but not the second additive.

[0093] Example 7

[0094] This embodiment is different from Embodiment 1 in that the second additive is tris(trimethylsilyl)borate (TMSB).

[0095] Comparative Example 1

[0096] The difference between this comparative example and Example 1 is that no additive is added to the electrolyte.

[0097] Comparative Example 2

[0098] The difference between this comparative example and Example 1 is that the first additive accounts for 0.08% of the total mass of the high-voltage electrolyte; and the organic solvent accounts for 83.92% of the total mass of the high-voltage electrolyte.

[0099] Comparative Example 3

[0100] The difference between this comparative example and Example 1 is that the first additive accounts for 10% of the total mass of the high-voltage electrolyte; and the organic solvent accounts for 74% of the total mass of the high-voltage electrolyte.

[0101] Comparative Example 4

[0102] The difference between this comparative example and Example 1 is that the first additive is a compound represented by the following formula (II).

[0103]

[0104] Formula (II),

[0105] Test Case

[0106] The batteries in the above embodiments and comparative examples were tested for battery capacity and high temperature cycle retention rate.

[0107] High temperature cycle stability test (55°C): charge and discharge potential range is 3.5V~4.9V, charge to 4.9V at 1C constant current, charge to cut-off current ≤0.05C at 4.9V constant voltage, let stand for 5 minutes, discharge to 3.5V at 1C. Repeat 100 times.

[0108] The test parameters of the embodiments and comparative examples are summarized in Table 1 below:

[0109] Table 1

[0110] Battery capacity / Ah 100-cycle cycle retention rate (%) Example 1 12.5 90.2 Example 2 10.4 87.9 Example 3 12.3 82.1 Example 4 12.2 88.7 Example 5 12.0 85.5 Example 6 12.3 88.7 Example 7 12.2 89.6 Comparative Example 1 11.1 78.2 Comparative Example 2 12.0 79.3 Comparative Example 3 9.3 77.2 Comparative Example 4 11.6 83.2

[0111] By comparing the experimental results of Examples 1-3 and Comparative Examples 2-3, it can be seen that controlling the appropriate mass percentage of the additive has a significant impact on the performance of the lithium-ion battery, and too low or too high mass percentage will lead to a decrease in the electrochemical performance of the lithium-ion battery.

[0112] It can be seen from the experimental results of Examples 1 and 4-5 that the length of the methyl segment connected to the carboxyl oxygen in the first additive can affect the quality of film formation, thereby affecting the high-temperature cycle stability of the battery.

[0113] It can be seen from the experimental results of Example 6 that by adding only the first additive to the electrolyte without the assistance of other additives, the lithium-ion battery can have excellent high-temperature and high-pressure cycle stability.

[0114] By comparing the experimental results of Example 1 and Examples 6-7, it can be seen that, on the basis of adding the first additive to the electrolyte, the additional addition of the second additive further improves the high-voltage and high-temperature cycle stability of the lithium-ion battery.

[0115] By comparing the experimental results of Example 1 and Comparative Example 4, it can be seen that after the trifluoromethyl group in the molecular structure of the first additive is converted into a difluoromethyl group, the effect of improving the battery cycle stability is greatly reduced.

[0116] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above 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.

[0117] The above 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 patent application. 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 application shall be subject to the attached claims.

Claims

1. A high voltage electrolyte, characterized in that: The invention comprises an electrolyte salt, an organic solvent and an additive, wherein the additive comprises a first additive, and the first additive is a compound represented by the following formula (I): Formula (I), Where n is 0~5; The first additive accounts for 0.1% to 5% of the total mass of the high voltage electrolyte.

2. The high voltage electrolyte according to claim 1, characterized in that: The additive further includes a second additive including at least one of a sultone compound, a cyclic sulfate ester compound, a phosphate ester compound, and a borate ester compound.

3. The high voltage electrolyte according to claim 2, characterized in that: The second additive accounts for 1% to 10% of the total mass of the high voltage electrolyte.

4. The high voltage electrolyte according to claim 1, characterized in that: The electrolyte salt includes at least one of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium bis(fluorosulfonyl)imide, lithium tetrafluoroborate, and lithium bis(trifluoromethanesulfonyl)imide.

5. The high voltage electrolyte according to claim 4, characterized in that: The electrolyte salt accounts for 0.5% to 20% of the total mass of the high voltage electrolyte.

6. The high voltage electrolyte according to claim 1, characterized in that: The organic solvent includes a carbonate compound and / or a carboxylate compound; Preferably, the organic solvent accounts for 1% to 90% of the total mass of the high voltage electrolyte.

7. The high voltage electrolyte according to claim 6, characterized in that: The carbonate compound includes at least one of fluoroethylene carbonate, difluoropropylene carbonate, trifluoroethyl methyl carbonate, trifluoromethylethylene carbonate, 4-trifluoromethylethylene carbonate, chloroethylene carbonate, di(2,2,2-trifluoroethyl) carbonate, 1,1,1,3,3,3-hexafluoroisopropyl acrylate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate.

8. The high voltage electrolyte according to claim 6, characterized in that: The carboxylate compound includes at least one of propyl fluorobutyrate, propyl fluoroacetate, ethyl fluoroacetate, isopropyl fluoroacetate, butyl fluoropropionate, isopropyl fluoropropionate, ethyl fluorobutyrate, methyl fluoropropionate, ethyl fluoropropionate, propyl fluoropropionate, ethyl acetate, methyl acetate, propyl butyrate, propyl acetate, isopropyl acetate, butyl propionate, isopropyl propionate, ethyl butyrate, methyl propionate, ethyl propionate, and propyl propionate.

9. A lithium ion battery, characterized in that: The invention comprises a positive electrode, a negative electrode, a separator and an electrolyte, wherein the electrolyte is the high voltage electrolyte according to any one of claims 1 to 8.

10. The lithium ion battery according to claim 9, characterized in that: The positive electrode includes a positive electrode material, and the positive electrode material includes at least one of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel manganese oxide, lithium-rich manganese-based materials, lithium vanadium phosphate, and ternary materials.

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