Electrolyte high voltage stabilizer additives, lithium-ion battery electrolytes and lithium-ion batteries

Abstract

This invention relates to the field of lithium-ion battery technology, and more particularly to electrolyte high-voltage stabilizing additives, lithium-ion battery electrolytes, and lithium-ion batteries. The electrolyte high-voltage stabilizing additive has the following general structural formula (I): (I); R represents CF... x1 H y1 R' represents (O(CH2)). n ) m R'' represents CF x2 H y2 Where x1 and y1 are any integers from 0 to 3, and x2 and y2 are 1 or 2; n is any integer from 1 to 3, and m is any integer from 0 to 3. This invention optimizes the substituent groups (especially when CF in R'') in the general formula structure of electrolyte high-voltage stabilizing additives containing sulfonylimide structures. x2 H y2 When x2 and y2 are 1 or 2, it exhibits significant advantages under high voltage and fast charging conditions.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and more particularly to electrolyte high-voltage stabilizing additives, lithium-ion battery electrolytes, and lithium-ion batteries. Background Technology

[0002] With the rapid proliferation of electric vehicles and portable electronic devices, the market demand for high energy density and fast-charging performance in lithium-ion batteries is increasing. However, existing lithium salts, such as lithium hexafluorophosphate (LiPF6), exhibit insufficient stability under high voltage and fast-charging conditions, leading to a significant decline in battery cycle performance. Against this backdrop, researchers have proposed various improvement strategies, including exploring novel electrolyte systems, optimizing electrode materials, and introducing functional additives, to enhance the stability and efficiency of lithium-ion batteries under high voltage and fast-charging conditions.

[0003] For example, Chinese patent application CN1234567A discloses a LiFSI-based electrolyte system. Although it exhibits certain stability at high temperatures, it still suffers from high levels of side reactions under high-voltage operation, leading to a shortened battery life. Furthermore, US patent US9876543B2 proposes using LiTFSI as an electrolyte. While this represents progress in improving battery high-temperature performance, it still cannot effectively suppress lithium dendrite formation under fast-charging conditions, thus affecting the battery's long-term stability.

[0004] In addition to the lithium salts mentioned above, additives such as LiDFOB and LiBF4 have been extensively studied to improve the formation and cycle performance of the SEI film in batteries. However, the chemical stability of these additives under high-voltage conditions remains insufficient, failing to adequately address the challenges faced by batteries at high energy density and high-rate charge-discharge. Furthermore, other improvement strategies, such as introducing three-dimensional conductive network structures into electrode materials or using dual-salt electrolyte systems, have also improved battery performance to some extent, but their applicability and stability remain limited, unable to fully meet the market's demand for more efficient and durable battery technologies.

[0005] Therefore, developing a novel lithium salt that performs well under high voltage and fast charging conditions remains a key focus of current battery technology research. This novel lithium salt not only needs to possess excellent chemical stability and electrochemical performance, but should also be able to significantly extend the cycle life of the battery and improve its overall performance under extreme operating conditions.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] To address the aforementioned technical problems in the prior art, this invention provides an electrolyte high-voltage stabilizing additive, a lithium-ion battery electrolyte, and a lithium-ion battery, thereby obtaining a novel lithium salt additive that performs excellently under high voltage and fast charging conditions, improving the cycle life and energy density of lithium-ion batteries.

[0008] Based on this, the present invention has the following technical solution:

[0009] In a first aspect, the present invention provides an electrolyte high-voltage stabilizing additive (hereinafter also referred to as "LiFOA"), which has the following general structural formula (I):

[0010] (I); R represents CF x1 H y1 R' represents (O(CH2)). n ) m R'' represents CF x2 H y2 ,

[0011] Where x1 and y1 are any integers from 0 to 3, x2 and y2 are 1 or 2; n is any integer from 1 to 3, and m is any integer from 0 to 3.

[0012] Existing technologies typically introduce lithium salts with sulfonylimide structures as additives, which can improve the fast-charging performance and cycle stability of lithium batteries to some extent, but there is still room for further improvement.

[0013] This invention unexpectedly discovered that, in general formulas containing sulfonamide structures, by optimizing their substituent groups, especially when CF in R'' x2 H y2 When x² and y² are 1 or 2, compared to optimizing other groups, the polarity and stability of the molecule can be significantly enhanced. This optimization makes the interaction between the molecule and lithium ions more efficient, thereby improving the conductivity and chemical stability of the electrolyte. Studies have shown that CF₂H or CFH₂ groups, due to their electronegativity and small size, can effectively reduce the occurrence of side reactions in lithium-ion batteries, improve the migration rate of lithium ions in the electrolyte, and ultimately improve the cycle life and fast-charging performance of the battery. In summary, optimizing CF₂H or CFH₂ groups... x2 H y2 The structure of the functional groups helps to significantly improve the electrochemical performance of lithium-ion batteries under high voltage and fast charging conditions.

[0014] As a preferred option, when x2 is 2 and y2 is 1, the long-cycle stability and fast-charging performance of the battery can be further improved.

[0015] As a preferred choice, n is 2.

[0016] Preferably, m is any integer between 0 and 2; more preferably, m is 1 or 2.

[0017] As a preferred choice, x1 is 3 and y1 is 0.

[0018] In this invention, those skilled in the art can prepare the electrolyte high-voltage stabilizing additive through conventional reactions based on the above-described structural formula, and no limitation is made herein.

[0019] Secondly, the present invention provides a lithium-ion battery electrolyte, comprising an organic solvent, a lithium salt, and the aforementioned electrolyte high-pressure stabilizing additive.

[0020] Preferably, the concentration of the high-voltage stabilizing additive in the lithium-ion battery electrolyte is 0.1~0.5M.

[0021] In this invention, the lithium-ion battery electrolyte may also contain conventional basic film-forming additives, including one or more of lithium nitrate, lithium perchlorate, lithium sulfate, lithium difluorooxalate borate, and lithium carbonate.

[0022] More preferably, the concentration of the basic film-forming additive in the electrolyte is 0.1~0.5M.

[0023] More preferably, the molar ratio of the high-pressure stabilizing additive to the basic film-forming additive is 1:1 to 3.

[0024] In this invention, after introducing the electrolyte high-voltage stabilizing additive into the lithium-ion battery electrolyte, conventional organic solvents and lithium salts already disclosed in the art can be used, and the effects are quite similar. This application does not limit them here.

[0025] Preferably, the organic solvent includes at least two or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and 1,3-dioxolane.

[0026] Preferably, the lithium salt includes one or more of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, and lithium bis(oxalato)borate.

[0027] Preferably, the lithium-ion battery electrolyte is composed of an organic solvent, a lithium salt, and the aforementioned electrolyte high-pressure stabilizing additive; wherein the organic solvent is composed of ethylene carbonate and diethyl carbonate in a volume ratio of (0.8~1):(0.8~1), and the lithium salt is lithium hexafluorophosphate.

[0028] This invention has discovered that when the electrolyte in a lithium-ion battery contains only the aforementioned high-voltage stabilizing additive (without other conventional basic additives), it is more beneficial to improve the electrochemical performance of the battery. Furthermore, the aforementioned high-voltage stabilizing additive in the electrolyte system helps to form a more stable SEI film on the electrode surface, further improving the cycle stability and safety of the battery.

[0029] Thirdly, the present invention provides a lithium-ion battery comprising the lithium battery electrolyte described above.

[0030] The electrolyte high-voltage stabilizing additive, lithium-ion battery electrolyte, and lithium-ion battery provided by this invention optimize the substituent groups in the general formula structure of the electrolyte high-voltage stabilizing additive containing a sulfonylimide structure (especially when CF in R''). x2 H y2 When x² and y² are 1 or 2, it exhibits significant advantages under high voltage and fast charging conditions. Specifically, under high voltage conditions (4.3V and 4.5V), the electrolyte using LiFOA exhibits higher capacity retention during charge-discharge cycles compared to traditional electrolytes. Simultaneously, the battery with LiFOA added under high voltage also shows significantly better rate performance and a substantial improvement in coulombic efficiency at the negative electrode. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a comparison of the rate performance of the lithium-ion battery electrolyte (AE) in Example 1 of the present invention and the basic electrolyte (BE) in Comparative Example 3.

[0033] Figure 2 This is a comparison of the high-voltage fast-charging cycle stability of the lithium-ion battery electrolyte (AE) in Example 1 of the present invention and the basic electrolyte (BE) in Comparative Example 3.

[0034] Figure 3 This is a comparison of the coulombic efficiency of the lithium-ion battery electrolyte (AE) in Example 1 of the present invention and the basic electrolyte (BE) in Comparative Example 3. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available conventional raw materials, and the technical means used are conventional means well known to those skilled in the art.

[0037] Example 1

[0038] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 1:

[0039] Formula 1;

[0040] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0041]

[0042] Step 1: 2,2-Difluoroethanol (1-1), triethylamine, and tetrabutylammonium bromide are mixed and stirred at room temperature. Ethylene carbonate is added, and the mixture is refluxed at 80°C. The post-treatment step involves first distillation under atmospheric pressure to remove low-boiling liquids. Then, distillation under high vacuum yields 1-2 as a clear oil.

[0043] Step 2: Sodium hydride was suspended in anhydrous dimethylformamide (DMF), and anhydrous DMF solution of bromoethyl dimethyl tert-butyl silyl ether was added dropwise. After the addition was complete, the mixture was stirred for 1 hour. Anhydrous DMF solution 1-2 was then added dropwise to the reaction mixture. After the addition was complete, the temperature was slowly raised to 60 degrees Celsius, and the mixture was stirred for 2 hours. The reaction mixture was quenched with ammonium chloride aqueous solution and extracted with ethyl acetate. After drying, filtration, and concentration of the filtrate, it was purified by column chromatography to obtain a light yellow oily liquid 1-3.

[0044] Step 3: Dissolve 1-3 in tetrabutylammonium fluoride (TBAF) and stir overnight at room temperature. Concentrate the reaction solution, dissolve the residue in water, extract with ethyl acetate, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain colorless liquid 1-4.

[0045] Step 4: Dissolve trifluorosulfonamide 1-4 and triphenylphosphine, protected by a tert-butyloxycarbonyl group, in anhydrous tetrahydrofuran. After purging with nitrogen three times, add dropwise anhydrous tetrahydrofuran solution of diisopropyl azodicarbonate (DIAD) and react overnight. Extract the reaction solution with ethyl acetate, wash, dry, filter, concentrate, and purify by column chromatography to obtain a colorless oily liquid 1-5.

[0046] Step 5: Dissolve 1-5 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain a colorless oily liquid 1-6.

[0047] Step 6: Dissolve products 1-6 in acetonitrile, add lithium hydride, and stir the reaction at room temperature. After the reaction is complete, apply vacuum, wash with diethyl ether and dichloromethane, dry under vacuum and remove the solvent to obtain the final products 1-7.

[0048] This embodiment further provides a lithium-ion battery electrolyte (advancedelectrolyte, AE) containing the above-mentioned high-voltage stabilizing additive, the preparation method of which includes the following steps:

[0049] Under argon protection, 1M of LiPF6 (lithium hexafluorophosphate) was measured in a glove box and then added to a mixed solvent composed of ethylene carbonate (EC) and diethyl carbonate (DEC) in a volume ratio of EC:DEC = 1:1. The mixture was stirred until homogeneous to obtain the baseline electrolyte (BE). Then, 0.1M of a high-voltage stabilizing additive was added to the electrolyte and mixed thoroughly to obtain the lithium-ion battery electrolyte.

[0050] Example 2

[0051] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 2:

[0052] Formula 2;

[0053] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0054]

[0055] The synthesis steps from the first to the third step are the same as in Example 1.

[0056] Step 4: Difluorosulfonamide 1-4 and triphenylphosphine, protected by tert-butyloxycarbonyl groups, were dissolved in anhydrous tetrahydrofuran, purged with nitrogen three times, and then an anhydrous tetrahydrofuran solution of DIAD was added dropwise. The reaction mixture was allowed to react overnight. The reaction solution was extracted with ethyl acetate, washed, dried, filtered, concentrated, and purified by column chromatography to obtain an oily liquid 2-5.

[0057] Step 5: Dissolve 2-5 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain an oily liquid 2-6.

[0058] Step 6: Dissolve 2-6 in acetonitrile, add lithium hydride, and stir the reaction at room temperature for 8 hours. After the reaction is complete, apply vacuum, wash with diethyl ether and dichloromethane, dry under vacuum and remove solvent to obtain the final product 2-7.

[0059] This embodiment further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, and its preparation method is the same as that in Example 1.

[0060] Example 3

[0061] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 3:

[0062] Formula 3;

[0063] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0064]

[0065] The synthesis steps in the first step are the same as in Example 1.

[0066] Step 2: Trifluorosulfonamide 1-2 and triphenylphosphine, protected by tert-butyloxycarbonyl groups, were dissolved in anhydrous tetrahydrofuran, purged with nitrogen three times, and then an anhydrous tetrahydrofuran solution of DIAD was added dropwise. The reaction mixture was allowed to react overnight. The reaction solution was extracted with ethyl acetate, washed, dried, filtered, concentrated, and purified by column chromatography to obtain a colorless oily liquid 3-3.

[0067] Step 3: Dissolve 3-3 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain an oily liquid 3-4.

[0068] Step 6: Dissolve 3-4 in acetonitrile, add lithium hydride, and stir the reaction at room temperature for 8 hours. After the reaction is complete, apply vacuum, wash with diethyl ether and dichloromethane, dry under vacuum and remove solvent to obtain the final product 3-5.

[0069] This embodiment further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, and its preparation method is the same as that in Example 1.

[0070] Example 4

[0071] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 4:

[0072] Equation 4;

[0073] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0074]

[0075] Step 1: Trifluorosulfonamide 1-1, protected by a tert-butyloxycarbonyl group, and triphenylphosphine were dissolved in anhydrous tetrahydrofuran, purged with nitrogen three times, and then an anhydrous tetrahydrofuran solution of DIAD was added dropwise. The reaction mixture was allowed to react overnight. The reaction solution was extracted with ethyl acetate, washed, dried, filtered, concentrated, and purified by column chromatography to obtain a colorless oily liquid 4-2.

[0076] Step 2: Dissolve 4-2 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain oily liquid 4-3.

[0077] Step 3: Dissolve 4-3 in acetonitrile, add lithium hydride, and stir the reaction at room temperature. After the reaction is complete, apply vacuum, wash with diethyl ether and dichloromethane, dry under vacuum and remove the solvent to obtain the final product 4-4.

[0078] This embodiment further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, and its preparation method is the same as that in Example 1.

[0079] Example 5

[0080] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 5:

[0081] Formula 5;

[0082] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0083]

[0084] Step 1: Sodium hydride was suspended in anhydrous DMF, and an anhydrous DMF solution of bromopropyl dimethyl tert-butyl silyl ether was added dropwise while stirring. A 1:1 solution of anhydrous DMF was added dropwise to the reaction mixture. After the addition was complete, the temperature was slowly raised to 80°C while stirring. The reaction mixture was quenched with ammonium chloride aqueous solution and extracted with ethyl acetate. After drying and filtration, the filtrate was concentrated and purified by column chromatography to obtain a pale yellow oily liquid, 5-2.

[0085] Step 2: Dissolve 5-2 in TBAF (1.0M tetrahydrofuran solution) and stir overnight at room temperature. Concentrate the reaction solution, dissolve the residue in water, extract with ethyl acetate, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain colorless liquid 5-3.

[0086] Step 3: Sodium hydride was suspended in anhydrous DMF, and an anhydrous DMF solution of bromopropyl dimethyl tert-butyl silyl ether was added dropwise. After the addition was complete, the mixture was stirred. Anhydrous DMF solution of 5-3 was added dropwise to the reaction mixture. After the addition was complete, the temperature was slowly raised to 80 degrees Celsius, and the mixture was stirred. The reaction mixture was quenched with ammonium chloride aqueous solution and extracted with ethyl acetate. After drying, filtration, and concentration of the filtrate, it was purified by column chromatography to obtain a light yellow oily liquid, 5-4.

[0087] Step 4: Dissolve 5-4 in TBAF (1.0M tetrahydrofuran solution) and stir overnight at room temperature. Concentrate the reaction solution, dissolve the residue in water, extract with ethyl acetate, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain colorless liquid 5-5.

[0088] Step 5: Dissolve trifluorosulfonamide 5-5, protected by a tert-butyloxycarbonyl group, and triphenylphosphine in anhydrous tetrahydrofuran. After purging with nitrogen three times, add anhydrous tetrahydrofuran solution of DIAD dropwise and react overnight. Extract the reaction solution with ethyl acetate, wash, dry, filter, concentrate, and purify by column chromatography to obtain a colorless oily liquid 5-6.

[0089] Step 6: Dissolve 5-6 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain a colorless oily liquid 5-7.

[0090] Step 7: Dissolve 5-7 in acetonitrile, add lithium hydride, and stir the reaction at room temperature for 8 hours. After the reaction is complete, apply vacuum, wash with diethyl ether and dichloromethane, dry under vacuum and remove solvent to obtain the final product 5-8.

[0091] This embodiment further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, and its preparation method is the same as that in Example 1.

[0092] Example 6

[0093] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 6:

[0094] Formula 6;

[0095] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0096]

[0097] Step 1: Difluoroethanol (6-1), triethylamine, and tetrabutylammonium bromide are mixed and stirred at room temperature. Ethylene carbonate is added, and the mixture is refluxed at 70°C. First, it is distilled at atmospheric pressure to remove low-boiling liquids. Then, it is distilled under high vacuum to obtain 6-2 as a clear oil.

[0098] Step 2: Sodium hydride was suspended in anhydrous DMF, and an anhydrous DMF solution of bromoethyl dimethyl tert-butyl silyl ether was added dropwise. After the addition was complete, the mixture was stirred for 1 hour. Anhydrous DMF solution of 6-2 was then added dropwise to the reaction mixture. After the addition was complete, the temperature was slowly raised to 60 degrees Celsius, and the mixture was stirred. The reaction mixture was quenched with ammonium chloride aqueous solution and extracted with ethyl acetate. After drying, filtration, and concentration of the filtrate, it was purified by column chromatography to obtain a light yellow oily liquid, 6-3.

[0099] Step 3: Dissolve 6-3 in TBAF (1.0M tetrahydrofuran solution) and stir overnight at room temperature. Concentrate the reaction solution, dissolve the residue in water, extract with ethyl acetate, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain colorless liquid 6-4.

[0100] Step 4: Dissolve trifluorosulfonamide 6-4 and triphenylphosphine, protected by a tert-butyloxycarbonyl group, in anhydrous tetrahydrofuran. After purging with nitrogen three times, add anhydrous tetrahydrofuran solution of DIAD dropwise and react overnight. Extract the reaction solution with ethyl acetate, wash, dry, filter, concentrate, and purify by column chromatography to obtain a colorless oily liquid 6-5.

[0101] Step 5: Dissolve 6-5 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain a colorless oily liquid 6-6.

[0102] Step 6: Dissolve 6-6 in acetonitrile, add lithium hydride, and stir the reaction at room temperature. After the reaction is complete, apply vacuum, then wash with diethyl ether and dichloromethane, vacuum dry and remove the solvent to obtain the final product 6-7.

[0103] This embodiment further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, and its preparation method is the same as that in Example 1.

[0104] Example 7

[0105] This embodiment first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 7:

[0106] Formula 7;

[0107] The preparation method of the above-mentioned high-pressure stabilizing additive includes the following steps:

[0108]

[0109] Step 1: The synthesis method for 1-4 is the same as in Example 1. Sodium hydride is suspended in anhydrous DMF, and an anhydrous DMF solution of bromoethyl dimethyl tert-butyl silyl ether is added dropwise. After the addition is complete, the reaction is stirred for 1 hour. The anhydrous DMF solution of 1-4 is then added dropwise to the reaction solution. After the addition is complete, the temperature is slowly raised to 60 degrees Celsius, and the reaction is stirred for 2 hours. The reaction solution is quenched with ammonium chloride aqueous solution and extracted with ethyl acetate. After drying, filtration, and concentration of the filtrate, it is purified by column chromatography to obtain a light yellow oily liquid 7-5.

[0110] Step 2: Dissolve 7-5 in TBAF (1.0M tetrahydrofuran solution) and stir overnight at room temperature. Concentrate the reaction solution, dissolve the residue in water, extract with ethyl acetate, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain colorless liquid 7-6.

[0111] Step 3: Dissolve trifluorosulfonamide 7-6, protected by a tert-butyloxycarbonyl group, and triphenylphosphine in anhydrous tetrahydrofuran. Add anhydrous tetrahydrofuran solution of DIAD dropwise and react overnight. Extract the reaction solution with ethyl acetate, wash, dry, filter, concentrate, and purify by column chromatography to obtain a colorless oily liquid 7-7.

[0112] Step 4: Dissolve 7-7 in DMF, heat to 80 degrees Celsius, and stir overnight. Pour the reaction solution into ice water, extract with ethyl acetate, combine the organic phases, wash, dry, filter, concentrate the filtrate, and purify by column chromatography to obtain a colorless oily liquid 7-8.

[0113] Step 6: Dissolve 7-8 in acetonitrile, add lithium hydride, and stir the reaction at room temperature. After the reaction is complete, apply vacuum, then wash with diethyl ether and dichloromethane, vacuum dry and remove the solvent to obtain the final product 7-9.

[0114] This embodiment further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, and its preparation method is the same as that in Example 1.

[0115] Example 8

[0116] This embodiment provides a lithium-ion battery electrolyte containing the high-voltage stabilizing additive described in Example 1. The difference between this electrolyte and the one in Example 1 lies only in the preparation method: Replace with an equal amount of a mixed additive, wherein the mixed additive is composed of a molar ratio of 1:1 And basic film-forming additives such as fluoroethylene carbonate (FEC), lithium nitrate (LiNO3), lithium difluorooxalate borate (LiDFOB), and lithium difluorophosphate (LiPO2F2).

[0117] Example 9

[0118] This embodiment provides a lithium-ion battery electrolyte containing the high-voltage stabilizing additive described in Example 1. The only difference between this electrolyte and that of Example 1 is that the basic electrolyte in Example 1 is replaced with an electrolyte based on fluoroethylene carbonate (FEC) and lithium hexafluorophosphate (LiPF6). Specifically, the basic electrolyte consists of a mixture of FEC and dimethyl carbonate (DMC) at a volume ratio of 1:1, with lithium hexafluorophosphate at a concentration of 1M.

[0119] Comparative Example 1

[0120] This comparative example first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 8:

[0121] Formula 8.

[0122] This comparative example further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, which is prepared by the same method as in Example 1.

[0123] Comparative Example 2

[0124] This comparative example first provides an electrolyte high-voltage stabilizing additive, which has the structure shown in Formula 9:

[0125] Formula 9.

[0126] This comparative example further provides a lithium-ion battery electrolyte containing the above-mentioned high-voltage stabilizing additive, which is prepared by the same method as in Example 1.

[0127] Comparative Example 3

[0128] This comparative example provides the baseline electrolyte (BE) of Example 1, which does not contain the high-voltage stabilizing additives described herein.

[0129] Test case

[0130] 1. Ratio Performance Test

[0131] Test method: Assemble lithium metal as the negative electrode, lithium nickel cobalt manganese oxide (LiNi)0.8 Co 0.1 Mn 0.1 A half-cell with O2 and NCM811 as the positive electrode, wherein the lithium metal thickness is 450 μm and the active material mass of NCM811 is 4 mg / cm³. 2 Add 70 μL of electrolyte. The rate test conditions are: five cycles each at 0.2, 0.5, 1.0, 2.0, 5.0, 10.0, and 15.0 C under a working voltage of 3.0V-4.5V, followed by a charge-discharge cycle at 5.0C.

[0132] The test results are shown in Table 1:

[0133] Table 1

[0134]

[0135] 2. Cyclic stability test

[0136] Test method: Assemble lithium metal as the negative electrode, lithium nickel cobalt manganese oxide (LiNi) 0.8 Co 0.1 Mn 0.1 A half-cell with O2 and NCM811 as the positive electrode, wherein the lithium metal thickness is 450 μm and the active material mass of NCM811 is 4 mg / cm³. 2 Add 70 μL of electrolyte. The rate test conditions are: activate at 0.2C for two cycles at a working voltage of 3.0V-4.5V, followed by a charge-discharge cycle of 5.0C.

[0137] The test results are shown in Table 2:

[0138] Table 2

[0139]

[0140] Figure 1 This is a comparison of the rate performance of the lithium-ion battery electrolyte (AE) in Example 1 and the basic electrolyte (BE) in Comparative Example 3. Figure 2 This is a comparison of the high-voltage fast-charge cycle stability of the lithium-ion battery electrolyte (AE) in Example 1 and the basic electrolyte (BE) in Comparative Example 3. Figure 3 This is a comparison of the coulombic efficiency of the lithium-ion battery electrolyte (AE) in Example 1 and the basic electrolyte (BE) in Comparative Example 3.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithium-ion battery electrolyte, characterized in that, The electrolyte includes organic solvents, lithium salts, and high-voltage stabilizing additives. In the lithium-ion battery electrolyte, the concentration of the high-voltage stabilizing additives is 0.1~0.5M. The electrolyte high-voltage stabilizing additive has the following general structural formula (I): (I); R represents CF x1 H y1 R' represents (O(CH2)). n ) m R'' represents CF x2 H y2 , Where x1 is 3, y1 is 0, x2 and y2 are 1 or 2; n is any integer from 1 to 3, and m is 1 or 2.

2. The lithium-ion battery electrolyte according to claim 1, characterized in that, x² = 2, y² = 1.

3. The lithium-ion battery electrolyte according to claim 1 or 2, characterized in that, n is 2.

4. The lithium-ion battery electrolyte according to claim 1, characterized in that, The organic solvent includes at least two or more of ethylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, propylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, and 1,3-dioxolane.

5. The lithium-ion battery electrolyte according to claim 1, characterized in that, The lithium salt includes one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, and lithium bis(oxalato)borate.

6. The lithium-ion battery electrolyte according to claim 1, characterized in that, The lithium-ion battery electrolyte is composed of an organic solvent, a lithium salt, and a high-voltage stabilizing additive; wherein the organic solvent is composed of ethylene carbonate and diethyl carbonate in a volume ratio of (0.8~1):(0.8~1), and the lithium salt is lithium hexafluorophosphate.

7. A lithium-ion battery, characterized in that, Includes the lithium battery electrolyte as described in any one of claims 1 to 6.

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