Electrolyte additive as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to an electrolyte additive and a preparation method and application thereof. The electrolyte additive comprises a bis-substituted sulfimide lithium salt as shown in a formula 1, wherein the bis-substituted sulfimide lithium salt as shown in the formula 1 comprises a carbon-carbon double bond structure; in the formula 1, R1 comprises any one of a formula 2a, a formula 2b and a formula 2c; r2 comprises any one of an alkyl group of C1-C3 and a halogenated alkyl group of C1-C3, and the halogenated alkyl group is a fluoroalkyl group; formula 2a, Formula 2b, Formula 2c. When the electrolyte containing the electrolyte additive is applied to the lithium battery, the cycle performance and the capacity retention ratio of the lithium battery can be improved, and the service life of the battery is prolonged.

Description

Technical Field

[0001] This application belongs to the field of battery technology, specifically relating to electrolyte additives and their preparation methods and applications, and more specifically, to electrolyte additives and their preparation methods, electrolytes, lithium batteries, battery packs and electrical devices. Background Technology

[0002] Lithium-ion batteries have become the most promising high-energy-density batteries due to their low electrode potential and high theoretical specific capacity. During multiple charge-discharge cycles, uneven deposition of lithium ions on the negative electrode surface can lead to the formation of lithium dendrites. These dendrites may puncture the separator, causing a short circuit and affecting battery safety and cycle life. While adding additives to the electrolyte can mitigate these problems to some extent, the additives are gradually consumed as the solid electrolyte interphase (SEI) membrane breaks down. This can cause a sudden drop in lithium-ion battery performance, affecting both battery performance and lifespan. Summary of the Invention

[0003] This application aims to at least partially address one of the technical problems in the related art. To this end, this application proposes an electrolyte additive, its preparation method, and its application. Applying an electrolyte containing this electrolyte additive to a battery can improve the cycle performance and capacity retention of lithium batteries.

[0004] In a first aspect of this application, an electrolyte additive is provided, comprising a bisubstituted sulfonylimide lithium salt as shown in Formula 1. Formula 1 Wherein, R1 includes any one of Equation 2a, Equation 2b and Equation 2c; R2 includes any one of C1-C3 alkyl groups and C1-C3 haloalkyl groups, wherein the haloalkyl group is a fluoroalkyl group; Equation 2a Equation 2b Equation 2c.

[0005] This application uses the bisubstituted sulfonylimide lithium salt shown in Formula 1 as an electrolyte additive, which can promote the formation of a stable solid electrolyte membrane (SEI membrane), thereby effectively inhibiting the growth of lithium dendrites and preventing continuously growing lithium dendrites from piercing the separator, making the lithium battery performance more stable. Therefore, it helps to improve the cycle performance and capacity retention of lithium batteries under high voltage, and helps to extend the cycle life of lithium batteries.

[0006] According to embodiments of this application, R2 includes at least one of -CH2F, -CF2H, -CF3, -CH2CF3, -CH2CH2F, -CH2CF2H, -CF2CF3, -CH2CF2CF3 and -CF2CF2CF3.

[0007] According to embodiments of this application, the bisubstituted sulfonylimide lithium salt of Formula 1 comprises at least one of the following compounds: Formula 1a Formula 1b Equation 1c.

[0008] A second aspect of this application provides a method for preparing electrolyte additives, comprising: Under inert gas protection, the R1 chloro derivative and thiourea are brought into contact in the first solvent and undergo a first reaction to obtain R1 substituted isothiourea; The R1-substituted isothiourea is mixed with a second solvent to obtain a first mixture; The first mixture and tert-butyl hypochlorite were brought into contact in a second solvent and a second reaction was carried out to obtain R1-substituted thioyl chloride; Under inert gas protection, the R1-substituted thiocyanate chloride and potassium source are mixed in a third solvent to obtain a second mixture; The R2-substituted sulfonamide is mixed with the second mixture and a third reaction is carried out to give the disubstituted sulfonylimide potassium salt; The disubstituted sulfonamide potassium salt is mixed with lithium tetrafluoroborate in a fourth solvent and a fourth reaction is carried out. A precipitant is added to precipitate the mixture, thereby obtaining the disubstituted sulfonamide lithium salt shown in Formula 1.

[0009] According to embodiments of this application, at least one of the following conditions is satisfied: The first solvent includes at least one of ethanol, methanol, and isopropanol; The molar ratio of the R1 chloro derivative, the thiourea, and the first solvent is 1:0.95-1.2:14-18; The temperature of the first reaction is 80℃-120℃; The first reaction takes 1-3 hours.

[0010] Therefore, under the above conditions, the reaction between R1 chloro derivative and thiourea is more complete, thereby improving the conversion rate of the reactants and the purity of the products.

[0011] According to embodiments of this application, at least one of the following conditions is satisfied: The second solvent includes distilled water and an aprotic solvent, wherein the aprotic solvent includes at least one of acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide; The molar ratio of the R1-substituted isothiourea, the distilled water, and the aprotic solvent is 1:8-12:70-90, wherein the molar ratio of the distilled water and the aprotic solvent is 8-12:70-90. The molar ratio of the R1-substituted isothiourea and the tert-butyl hypochlorite is 1:0.9-1.2; The temperature of the second reaction is 0℃-30℃; The second reaction takes 13-32 hours.

[0012] Therefore, under the above conditions, the reaction of R1-substituted isothiourea and tert-butyl hypochlorite is more complete, thereby improving the conversion rate of the reactants and the purity of the products.

[0013] According to embodiments of this application, at least one of the following conditions is satisfied: The third solvent includes at least one of acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide; The potassium source includes at least one of potassium carbonate, potassium sulfate, and potassium acetate. The molar ratio of the R1-substituted thioyl chloride, the potassium source, and the third solvent is 1:1-2:15-25; The molar ratio of the R2-substituted sulfonamide to the R1-substituted thioacryl chloride is 1:0.9-1.2; The temperature of the third reaction is 25℃-30℃; The third reaction takes 30-40 hours.

[0014] Therefore, under the above conditions, the reaction of R1-substituted thioyl chloride and R2-substituted sulfonamide is more complete, thereby improving the conversion rate of reactants and the purity of products.

[0015] According to embodiments of this application, at least one of the following conditions is satisfied: The fourth solvent includes at least one of acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, etc. The molar ratio of the lithium tetrafluoroborate and the potassium disulfonyl imide is 1:3-5; The temperature of the fourth reaction is 0℃-30℃; The fourth reaction takes 10-30 hours; The precipitant includes at least one of diethyl ether and petroleum ether.

[0016] Therefore, under the above conditions, the reaction between lithium tetrafluoroborate and disubstituted sulfonylimide potassium salt is more complete, thereby improving the conversion rate of the reactants and the purity of the products.

[0017] A third aspect of this application provides an electrolyte comprising an organic solvent, an electrolyte salt, and the aforementioned electrolyte additives. All the features and advantages of this electrolyte are consistent with those of the aforementioned electrolyte additives, and will not be repeated here.

[0018] According to embodiments of this application, the concentration of the electrolyte additive in the electrolyte is 0.02 mol / L to 0.2 mol / L. Therefore, within the above concentration range, it helps to improve the cycle performance, capacity retention, and stability of the lithium battery under high voltage, and also helps to extend the cycle life of the lithium battery.

[0019] According to embodiments of this application, the electrolyte salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(oxalate-borate), and lithium bis(oxalate-borate). Specifically, the electrolyte salt includes at least one of an electrolyte salt composed of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide. Therefore, the above-mentioned electrolyte salt has high ionic conductivity, low resistance, and good chemical stability, enabling lithium batteries using this electrolyte to have advantages such as high energy density and long cycle life.

[0020] According to embodiments of this application, the concentration of the electrolyte salt in the electrolyte is 0.1 mol / L to 5 mol / L, specifically, 0.5 mol / L to 2 mol / L. Therefore, within the above concentration range, the electrolyte exhibits better conductivity and electrochemical stability.

[0021] According to embodiments of this application, the organic solvent includes at least one selected from ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, methyl formate, methyl acetate, ethyl acetate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate. Specifically, the organic solvent includes at least one selected from a mixed solvent composed of tetrahydrofuran, tetrahydrofuran, and methyltetrahydrofuran. Therefore, after dissolving the electrolyte salt, the above-mentioned organic solvent can give the electrolyte a high ionic conductivity, thereby enabling the lithium battery to have advantages such as high capacity retention and long cycle life.

[0022] A fourth aspect of this application provides a lithium battery comprising the electrolyte described above, a positive electrode, a negative electrode, and a separator. All the features and advantages of this lithium battery are consistent with those of the electrolyte described above, and will not be repeated here.

[0023] A fifth aspect of this application provides a battery pack comprising the battery described above. All features and advantages of this battery pack are consistent with those of the battery described above, and will not be repeated here.

[0024] A sixth aspect of this application provides an electrical device comprising the battery or battery pack described above. All features and advantages of this electrical device are consistent with those of the battery or battery pack described above, and will not be repeated here. Attached Figure Description

[0025] Figure 1 It is the bisubstituted sulfonylimide lithium salt of Example 1 of this application. 1 H NMR spectrum. Detailed Implementation

[0026] The embodiments of this application are described in detail below and are intended to explain this application, but should not be construed as limiting this application.

[0027] During multiple charge-discharge cycles of lithium batteries, uneven deposition of lithium ions on the negative electrode surface can lead to the formation of lithium dendrites. These dendrites may puncture the separator, causing a short circuit and affecting battery safety and cycle life. While adding additives to the electrolyte can mitigate these issues to some extent, the additives are gradually consumed as the solid electrolyte membrane breaks down, leading to a sudden decline in lithium battery performance and impacting both battery performance and lifespan.

[0028] Based on the above research, this application proposes a new electrolyte additive. When an electrolyte containing this additive is applied to a battery, a stable SEI film can be generated, thereby effectively inhibiting the growth of lithium dendrites and improving the cycle performance and capacity retention of the lithium battery.

[0029] In a first aspect of this application, an electrolyte additive is provided, comprising a bisubstituted sulfonylimide lithium salt as shown in Formula 1. Formula 1 Wherein, R1 includes any one of Equation 2a, Equation 2b and Equation 2c; R2 includes any one of C1-C3 alkyl groups and C1-C3 haloalkyl groups, wherein the haloalkyl group is a fluoroalkyl group; Equation 2a Equation 2b Equation 2c.

[0030] This application uses the bisubstituted sulfonylimide lithium salt shown in Formula 1 as an electrolyte additive. On the one hand, by adjusting the structure and composition of R1 and R2 in the additive, the LUMO (lowest unoccupied molecular orbital) energy level can be significantly reduced, prompting the electrolyte additive to preferentially react on the negative electrode surface, forming abundant inorganic lithium salts such as Li2S, Li3N, and LiF. These inorganic lithium salts work synergistically to generate a stable solid electrolyte membrane (SEI membrane), thereby effectively inhibiting the growth of lithium dendrites and preventing continuously growing lithium dendrites from piercing the separator, thus better protecting the positive and negative electrode interfaces and making the lithium battery performance more stable. On the other hand, the SEI membrane rich in various inorganic components helps to improve the cycle performance and capacity retention of high-voltage lithium batteries. Specifically, Li3N is a layered solid electrolyte with two-dimensional ion migration channels and a room temperature conductivity of up to 10. -3 The electrolyte additive exhibits high ionic conductivity (S / cm) and high thermal stability, allowing it to form a dense and rigid SEI film together with LiF. Furthermore, this electrolyte additive enhances the toughness and repair capabilities of the SEI film during its formation. When the SEI film ruptures, the active ingredients in the electrolyte additive can fill the rupture and rebuild a stable SEI film structure.

[0031] The above characteristics enable batteries assembled with electrolytes made using the additives of this application to have higher coulombic efficiency, higher energy utilization of lithium batteries, and extended battery life. In summary, the electrolyte additives shown in Formula 1 used in this application help improve the cycle performance and capacity retention of lithium batteries under high voltage, and help extend the cycle life of lithium batteries.

[0032] In this paper, coulombic efficiency refers to the percentage of discharged energy to charged energy during the charging and discharging process of a battery. It reflects the effective utilization of charge in the battery during charge-discharge cycles. It can be obtained by performing constant current density charge-discharge cycle tests on assembled Li / / Cu half-cells.

[0033] In this article, the term "C1-C3 alkyl" refers to a saturated straight-chain or branched monovalent hydrocarbon group containing 1-3 carbon atoms. The structural formula of C1-C3 alkyl includes, but is not limited to, methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), and isopropyl (-CH(CH3)2).

[0034] The term "C1-C3 haloalkyl" means that at least one carbon atom in a C1-C3 alkyl group is substituted with a halogen (F, Cl, Br, I).

[0035] According to embodiments of this application, R2 includes at least one of -CH2F, -CF2H, -CF3, -CH2CF3, -CH2CH2F, -CH2CF2H, -CF2CF3, -CH2CF2CF3, and -CF2CF2CF3. This increases the polarity of the electrolyte additive, improves its solubility and dispersibility in the electrolyte, ensures its uniform distribution in the electrolyte, and thereby uniformly forms an SEI film on the electrode surface, further improving the quality and performance of the SEI film.

[0036] According to embodiments of this application, the bisubstituted sulfonylimide lithium salt of Formula 1 comprises at least one of the following compounds: Formula 1a Formula 1b Equation 1c.

[0037] A second aspect of this application provides a method for preparing electrolyte additives, comprising: S10: Under inert gas protection, the chloro derivative of R1 and thiourea are brought into contact in the first solvent and undergo the first reaction to obtain R1 substituted isothiourea.

[0038] In this step, before the reaction begins, the reaction system is purged with an inert gas. Then, the R1 chloro derivative and thiourea are mixed in the first solvent and reacted. After the reaction is complete, the reaction solution undergoes a first post-treatment to obtain R1-substituted isothiourea. The reaction equation for this process is shown below.

[0039] According to embodiments of this application, the inert gas includes at least one of nitrogen and argon. This allows air and moisture in the reaction system to be displaced, preventing side reactions.

[0040] According to embodiments of this application, the first solvent includes at least one selected from ethanol, methanol, and isopropanol. Therefore, the aforementioned solvent helps to completely dissolve the reactants, allowing them to react fully and improving the utilization rate of the reactants.

[0041] According to embodiments of this application, the molar ratio of the R1 chloroproduct, the thiourea, and the first solvent is 1:0.95-1.2:14-18, specifically 1:0.95:14, 1:1:15, 1:1.1:16, 1:1.05:16, 1:1.2:17, 1:1.2:18, or any two of these ranges. Therefore, within the above range, it is beneficial for the R1 chloroproduct and the thiourea to fully dissolve and react in the first organic solvent, thereby increasing the yield of the product.

[0042] According to embodiments of this application, the temperature of the first reaction is 80℃-120℃, specifically 80℃, 85℃, 90℃, 95℃, 100℃, 105℃, 110℃, 115℃, 120℃, or any range between two of these. Therefore, within the above temperature range, it helps to increase the reaction rate, ensure the reaction proceeds fully, and thus increase the product yield. If the temperature is too low, the reaction rate may be too low, thereby increasing time costs; if the temperature is too high, the first solvent may evaporate rapidly, resulting in an excessively high concentration in the reaction system, making the reaction too vigorous and increasing the risk.

[0043] According to embodiments of this application, the first reaction time is 1-3 hours, specifically 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, or any combination thereof. This timeframe facilitates sufficient reaction between reactants, increasing product yield. If the reaction time is too short, the reactants may not react sufficiently, thus reducing product yield; if the time is too long, the conversion rate of the reactants may no longer change significantly, increasing time costs.

[0044] According to embodiments of this application, the first post-treatment includes evaporating the first solvent and washing 3-5 times with solvents such as diethyl ether and dichloromethane, followed by evaporation to obtain R1-substituted isothiourea. This removes unreacted reactants and other soluble impurities, improving the purity of the product.

[0045] S20: The R1-substituted isothiourea is mixed with a second solvent to obtain a first mixture.

[0046] In this step, there are no specific limitations on the mixing method and time, as long as R1 replaces isothiourea and is mixed evenly. In some embodiments, stirring can be used; in other embodiments, ultrasonication can be used.

[0047] According to embodiments of this application, the second solvent comprises distilled water and an aprotic solvent, wherein the aprotic solvent comprises at least one selected from acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide. Thus, the aforementioned solvents facilitate the complete dissolution of the reactants.

[0048] According to an embodiment of this application, the mixing temperature is a 0°C ice-water bath. This helps control the heat release during the mixing process and avoids the dangers caused by violent heat release.

[0049] S30: The first mixture and tert-butyl hypochlorite are brought into contact in a second solvent and a second reaction is carried out to obtain R1-substituted thioyl chloride.

[0050] In this process, tert-butyl hypochlorite is first diluted with a first diluent, and then the solution is added dropwise to a first mixture under an ice-water bath at 0°C to initiate the reaction. After the reaction is complete, the reaction solution undergoes a second post-treatment to obtain R1-substituted thioyl chloride. The reaction equation for this process is shown below:

[0051] According to embodiments of this application, the molar ratio of the R1-substituted isothiourea, the distilled water, and the aprotic solvent is 1:8-12:70-90, specifically 1:8:70, 1:9:75, 1:10:80, 1:11:85, 1:12:90, or any range thereof, wherein the molar ratio of the distilled water and the aprotic solvent is 8-12:70-90. Therefore, within the above range, it is beneficial for the R1-substituted isothiourea to fully dissolve and react in the second organic solvent, thereby increasing the product yield.

[0052] According to embodiments of this application, the molar ratio of R1-substituted isothiourea to tert-butyl hypochlorite is 1:0.9-1.2, specifically 1:0.9, 1:1, 1:1.1, 1:1.2, or any range between two of these. Within this range, it facilitates a complete reaction between R1-substituted isothiourea and tert-butyl hypochlorite, improving the utilization rate of the reactants. If the molar ratio is too high, it indicates that too much R1-substituted isothiourea has been added, which may lead to incomplete reaction and residue, thus affecting the purity of the product. If the molar ratio is too low, it indicates that too much tert-butyl hypochlorite has been added, which may also lead to incomplete reaction and residue, thus affecting the purity of the product.

[0053] According to embodiments of this application, the first diluent includes at least one selected from acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide, and is the same as the aprotic solvent. This facilitates the complete dissolution of tert-butyl hypochlorite, and the reduced concentration after dilution avoids an overly vigorous reaction and minimizes the occurrence of side reactions.

[0054] According to embodiments of this application, the molar ratio of tert-butyl hypochlorite to the first diluent is 5-15:70-90, specifically 5:70, 7:75, 10:80, 12:85, 15:90, or any range between two of these. Within this range, tert-butyl hypochlorite can be fully dissolved while reducing its concentration, ensuring the mildness and controllability of the reaction, and improving its safety and efficiency. If the molar ratio is too low, it indicates that the concentration of tert-butyl hypochlorite is too high, which may lead to an overly vigorous reaction during the dropwise addition, resulting in localized overheating and increasing safety risks. If the molar ratio is too high, it indicates that the content of the first diluent is too high, which may result in a low concentration in the reaction system, thereby reducing the reaction rate, prolonging the reaction time, and increasing time costs.

[0055] According to embodiments of this application, the dropping rate of the first mixture is 10 drops / min to 30 drops / min, for example, 15 drops / min, 20 drops / min, 25 drops / min, or 30 drops / min. Therefore, within the above-mentioned dropping rate range, it helps to control the reaction rate and maintain the homogeneity of the reaction system. If the dropping rate is too fast, it may lead to excessively high local concentrations in the reaction system, resulting in side reactions; if the dropping rate is too slow, it may significantly prolong the reaction time, thereby reducing reaction efficiency.

[0056] According to embodiments of this application, the second reaction is carried out at a temperature of 0°C-30°C for 12-32 hours. In some examples, the reaction is first carried out in an ice-water bath at 0°C for 0.5-2 hours, and then the temperature is gradually increased to 20°C-30°C for 12-30 hours. Therefore, initially reacting in an ice-water bath at 0°C helps control the reaction rate at the beginning of the reaction, avoiding an overly vigorous reaction, thereby reducing side reactions and increasing product yield. Then, after the reaction stabilizes, increasing the temperature to 20°C-30°C can accelerate the reaction rate and shorten the reaction time, thereby improving production efficiency and reducing time costs while ensuring product quality.

[0057] According to embodiments of this application, the second post-treatment includes evaporating the second solvent and washing 3-5 times with solvents such as diethyl ether and dichloromethane. The clear solution after washing is collected, evaporated, and then R1-substituted thiocyanate chloride is obtained. This removes unreacted reactants and other soluble impurities, improving the purity of the product.

[0058] S40: Under inert gas protection, the R1-substituted thiocyanate chloride and potassium source are mixed in a third solvent to obtain a second mixture.

[0059] In this step, there are no specific restrictions on the order of adding the materials or the mixing time, as long as the R1-substituted sulfuryl chloride and the potassium source are mixed evenly. In some embodiments, the R1-substituted sulfuryl chloride can be dissolved first and then the potassium source can be added for mixing; in other embodiments, the R1-substituted sulfuryl chloride and the potassium source can be added together before mixing.

[0060] According to embodiments of this application, the inert gas includes at least one of nitrogen and argon. This allows air and moisture in the reaction system to be displaced, preventing side reactions.

[0061] According to embodiments of this application, the third solvent includes at least one selected from acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide. Therefore, the aforementioned solvents facilitate complete dissolution of the reactants and prevent side reactions with R1-substituted thiocyanate chlorides, thereby contributing to improved reactant conversion.

[0062] According to embodiments of this application, the potassium source includes at least one of potassium carbonate, potassium sulfate, and potassium acetate. Therefore, the aforementioned potassium source exhibits good solubility in a third solvent and is inexpensive and readily available.

[0063] According to embodiments of this application, the molar ratio of the R1-substituted thiocyanate chloride, the potassium source, and the third solvent is 1:1-2:15-25, specifically 1:1:15, 1:1.3:18, 1:1.5:20, 1:1.8:23, 1:1.2:25, or any combination thereof. Therefore, within the above range, it is beneficial for the R1-substituted thiocyanate chloride, the potassium source, and the R2-substituted sulfonamide to fully dissolve and react in the third organic solvent, thereby increasing the yield of the product.

[0064] S50: Mix the R2-substituted sulfonamide with the second mixture and allow a third reaction to occur, yielding a disubstituted sulfonamide potassium salt.

[0065] In this step, the R2-substituted sulfonamide is first diluted with a second diluent, and then added dropwise to a second mixture to initiate the reaction. After the reaction is complete, a third post-treatment is performed to obtain the disubstituted sulfonamide potassium salt. The reaction equation for this process is shown below:

[0066] According to embodiments of this application, the second diluent includes at least one selected from acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide, and is the same as the second solvent. This facilitates the complete dissolution of tert-butyl hypochlorite, and the concentration is reduced after dilution, thereby avoiding an overly vigorous reaction and minimizing side reactions.

[0067] According to embodiments of this application, the molar ratio of R2-substituted sulfonamide to the second diluent is 0.9-1.1:10, specifically 0.9:10, 0.95:10, 1:10, 1.05:10, 1.1:10, or any range between two of these. Within this range, the R2-substituted sulfonamide is readily dissolved, while simultaneously reducing its concentration, ensuring a mild and controllable reaction, and improving the safety and efficiency of the reaction. If the molar ratio is too low, it indicates that the concentration of R2-substituted sulfonamide is too high, which may lead to an overly vigorous reaction during the dropwise addition, resulting in localized overheating and increasing safety risks. If the molar ratio is too high, it indicates that the content of the second diluent is too high, which may result in a low concentration in the reaction system, thereby reducing the reaction rate, prolonging the reaction time, and increasing time costs.

[0068] According to embodiments of this application, the dropping rate of the second mixture is 10 drops / min to 30 drops / min, for example, 15 drops / min, 20 drops / min, 25 drops / min, or 30 drops / min. Therefore, within this dropping rate range, it helps to control the reaction rate and maintain the homogeneity of the reaction system. If the dropping rate is too fast, it may lead to excessively high local concentrations in the reaction system, resulting in side reactions; if the dropping rate is too slow, it may significantly prolong the reaction time, thereby reducing reaction efficiency.

[0069] According to embodiments of this application, the molar ratio of the R2-substituted sulfonamide to the R1-substituted sulfuryl chloride is 1:0.9-1.2, specifically 1:0.9, 1:1, 1:1.1, 1:1.2, or any combination thereof. This facilitates the complete reaction of the R2-substituted sulfonamide and the R1-substituted sulfuryl chloride, improving the conversion rate of the reactants. If the molar ratio is too high, it indicates that the amount of R2-substituted sulfonamide added is too high, which may lead to incomplete reaction of the R2-substituted sulfonamide and affect the yield of the product; if the molar ratio is too low, it indicates that the amount of R1-substituted sulfuryl chloride added is too high, which may also lead to incomplete reaction of the R1-substituted sulfuryl chloride and similarly affect the yield of the product.

[0070] According to embodiments of this application, the temperature of the third reaction is 25°C-30°C, specifically 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, or any two of these ranges. Within this temperature range, it helps to increase the reaction rate, ensuring the third reaction proceeds fully, thereby increasing the product yield. If the temperature is too low, the reaction rate may be too low, increasing time costs; if the temperature is too high, the third solvent may evaporate rapidly, resulting in an excessively high concentration in the reaction system, making the reaction too vigorous and increasing the risk.

[0071] According to embodiments of this application, the third reaction time is 30-40 hours, specifically 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, or any range between two of these. This timeframe facilitates sufficient reaction between reactants, increasing product yield. If the reaction time is too short, the reactants may not react sufficiently, thus reducing product yield; if the time is too long, the conversion rate of the reactants may no longer change significantly, increasing time costs.

[0072] According to an embodiment of this application, the third post-processing includes filtering the reaction solution, concentrating the obtained solid by rotary evaporation to remove residual third solvent, washing it 3-5 times with solvents such as diethyl ether and dichloromethane to remove residual unreacted reactants, filtering it again, collecting the solid and drying it to obtain disubstituted sulfonamide potassium salt.

[0073] S60: Mix the disubstituted sulfonamide potassium salt with lithium tetrafluoroborate in a fourth solvent and allow a fourth reaction to occur. Add a precipitant to precipitate the mixture and obtain the disubstituted sulfonamide lithium salt shown in Formula 1.

[0074] In this step, the potassium salt of the disubstituted sulfonamide is first dissolved in a fourth solvent to obtain a potassium salt solution; lithium tetrafluoroborate is dissolved in the fourth solvent to obtain a lithium salt solution, and then the lithium salt solution is added dropwise to the potassium salt solution to carry out the reaction. After the reaction is complete, a fourth post-treatment is performed to obtain the lithium salt of the disubstituted sulfonamide shown in Formula 1. The reaction equation for this process is shown below:

[0075] According to embodiments of this application, the fourth solvent includes at least one selected from acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide. Therefore, the aforementioned solvents possess good solubility, which helps to fully dissolve the reactants, thereby facilitating a complete reaction between the reactants and improving the conversion rate of the reactants.

[0076] According to embodiments of this application, the molar ratio of the disubstituted sulfonylimide potassium salt to the fourth solvent, and the molar ratio of lithium tetrafluoroborate to the fourth solvent, are each 1:20-40, specifically 1:20, 1:25, 1:30, 1:35, 1:40, or any range between two of these. This ensures complete dissolution of the reactants, facilitating a more thorough reaction between them and thus increasing the conversion rate of the reactants.

[0077] According to embodiments of this application, the molar ratio of lithium tetrafluoroborate to the potassium difluoroimide disulfonate is 1:3-5, specifically 1:3, 1:3.5, 1:4, 1:4.5, 1:5, or any range thereof. Within this range, it facilitates the complete conversion of the potassium difluoroimide disulfonate into lithium difluoroimide disulfonate. If the molar ratio is too low, it indicates that the amount of potassium difluoroimide disulfonate added is too high, which may result in a large amount of potassium difluoroimide disulfonate remaining, reducing the utilization rate of the reactants. If the molar ratio is too high, it indicates that the amount of lithium tetrafluoroborate added is too high, which may lead to side reactions, thereby reducing the utilization rate of the reactants.

[0078] According to embodiments of this application, the fourth reaction includes reacting at a temperature of 0°C-30°C for 10-35 hours. In some embodiments, the reaction can be initially carried out in an ice-water bath at 0°C for 0.5-1.5 hours, followed by heating to 25°C-30°C for 10-30 hours. Therefore, initially reacting in an ice-water bath at 0°C helps control the reaction rate at the beginning, preventing the reaction from becoming too vigorous, thereby reducing side reactions and increasing product yield. Then, after the reaction stabilizes, heating to 25°C-30°C can accelerate the reaction rate and shorten the reaction time, thereby improving production efficiency and reducing time costs while ensuring product quality.

[0079] According to an embodiment of this application, the fourth post-processing includes: centrifuging or filtering the reaction solution to remove insoluble impurities; then collecting the clear liquid, concentrating it to remove most of the fourth solvent, and obtaining a concentrated solution. A precipitant is added to the concentrated solution to precipitate a white solid. The white solid is centrifuged, and the supernatant is discarded. The resulting solid is the disubstituted sulfonylimide lithium salt.

[0080] According to embodiments of this application, the precipitant includes at least one of diethyl ether and petroleum ether. Therefore, the disubstituted sulfonylimide lithium salt has low solubility in the aforementioned solvent, which helps to promote the precipitation of the solid.

[0081] According to the embodiments of this application, there is no limit to the amount of precipitant added, as long as all the disubstituted sulfonylimide lithium salt is precipitated. The specific amount of precipitant added can be selected according to actual needs.

[0082] A third aspect of this application provides an electrolyte comprising an organic solvent, an electrolyte salt, and the electrolyte additives described above. All the features and advantages of this electrolyte are consistent with those of the electrolyte additives described above, and will not be repeated here.

[0083] According to embodiments of this application, the concentration of the electrolyte additive in the electrolyte is 0.02 mol / L to 0.2 mol / L, specifically within the ranges of 0.02 mol / L, 0.05 mol / L, 0.08 mol / L, 0.1 mol / L, 0.12 mol / L, 0.14 mol / L, 0.16 mol / L, 0.18 mol / L, 0.2 mol / L, or any two of these ranges. Therefore, within the above concentration range, it helps to improve the cycle performance, capacity retention, and stability of the lithium battery under high voltage, and helps to extend the cycle life of the lithium battery. If the concentration is too high, the electrolyte additive may not dissolve completely, affecting the performance of the lithium battery; if the concentration is too low, the improvement on the performance of the lithium battery may not be significant.

[0084] According to embodiments of this application, the electrolyte salt includes one or more of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(oxalate-borate), and lithium bis(oxalate-borate). Specifically, it includes at least one of a mixed lithium salt composed of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide. Therefore, the above-mentioned electrolyte salt has high ionic conductivity, low resistance, and good chemical stability, resulting in lithium batteries using this electrolyte exhibiting advantages such as high energy density and long cycle life.

[0085] According to an embodiment of the present application, the concentration of the electrolyte salt in the electrolyte solution is 0.1 mol / L - 5 mol / L. Specifically, it can be 0.2 mol / L - 2 mol / L, such as 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L or the range between any two of them. Thus, within the above concentration range, the electrolyte solution has better conductivity and electrochemical stability.

[0086] According to an embodiment of the present application, the organic solvent is at least one of ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3 - dioxolane, tetrahydrofuran, methyltetrahydrofuran, methyl formate, methyl acetate, ethyl acetate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and ethyl methyl carbonate. Specifically, the organic solvent is at least one of tetrahydrofuran and a mixed solvent composed of tetrahydrofuran and methyltetrahydrofuran. Thus, after dissolving the electrolyte salt, the above organic solvent can make the electrolyte solution have a high ionic conductivity, so that the lithium battery has advantages such as a high capacity retention rate and a long cycle life.

[0087] According to an embodiment of the present application, in the mixed solvent, the volume percentage content x of methyltetrahydrofuran in the mixed solvent satisfies: 0 < x ≤ 20%. Specifically, it can be 0.1% - 20%. More specifically, such as 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.5%, 1%, 5%, 8%, 10%, 12%, 15%, 17%, 20%. Thus, within the above range, the organic solvent has a high solubility of lithium salt and strong interfacial film - forming property. After synergistic compounding with the electrolyte additive, the electrolyte solution can have excellent bulk properties such as a low viscosity, good wettability, and a high ionic conductivity.

[0088] In the fourth aspect of the present application, a lithium battery is proposed, which includes the electrolyte solution described above, a positive electrode sheet, a negative electrode sheet, and a separator. All the features and advantages of this lithium battery are the same as those of the electrolyte solution described above, and will not be elaborated here one by one.

[0089] It can be understood that there is no particular limitation on the specific type of this lithium battery, and it can be a primary battery or a secondary battery. The shape of this lithium battery can be a cylindrical battery, a square battery, or any other shape battery, etc. Classified by the outer packaging, the lithium battery can be a hard - shell battery, a soft - pack battery, etc. According to the type of the negative electrode material, the lithium battery can be divided into a lithium - ion battery, a lithium - metal battery, etc.

[0090] In some embodiments, the lithium battery may include a positive electrode, a negative electrode, and a separator, etc. The positive electrode, negative electrode, and separator are all immersed in an electrolyte. During the charging and discharging process of the lithium battery, active ions are inserted and extracted back and forth between the positive and negative electrodes. The electrolyte plays the role of conducting ions between the positive and negative electrodes. The separator is disposed between the positive and negative electrodes, mainly to prevent short circuits between the positive and negative electrodes, while allowing active ions to pass through.

[0091] In some embodiments, the positive electrode sheet includes a positive current collector and a positive active material layer located at least on one side of the positive electrode sheet, the positive active material layer including a positive active material.

[0092] In some embodiments, the positive current collector can be a metal current collector or a composite current collector. For example, metal current collectors include, but are not limited to, aluminum foil current collectors; composite current collectors may include a polymer material substrate and a metal layer formed on at least one surface of the polymer material substrate. Composite current collectors can be formed by forming a metal material (copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver and silver alloy, etc.) on a polymer material substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), polyethylene (PE), etc.).

[0093] In some embodiments, the positive electrode active material of the lithium battery may include at least one of the following: layered structure positive electrode active materials (e.g., nickel-cobalt-manganese ternary positive electrode materials, nickel-cobalt-aluminum ternary positive electrode materials, lithium nickel oxide / sodium, lithium cobalt oxide / sodium, lithium manganese oxide / sodium, lithium-rich / sodium layered and rock salt phase layered materials), olivine-type phosphate active materials (e.g., lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, etc.), and spinel structure positive electrode active materials (e.g., spinel lithium manganese oxide, spinel lithium nickel manganese oxide, lithium-rich spinel lithium manganese oxide, and lithium nickel manganese oxide, etc.). As a specific example, this application uses nickel-cobalt-manganese ternary positive electrode materials. It is understood that the above-mentioned positive electrode active materials may further include doping elements and coating layers, etc.

[0094] In some embodiments, the positive electrode binder in the positive electrode active material layer may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), PVDF-tetrafluoroethylene-propylene terpolymer, PVDF-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorinated acrylate resin.

[0095] In some embodiments, the positive electrode conductive agent in the positive electrode active material layer may include at least one of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, Super P Li conductive carbon black, and carbon nanofibers.

[0096] In some embodiments, the negative electrode is made of lithium metal.

[0097] As an example, the negative electrode active material layer may include a negative electrode active material, a thickener, a negative electrode conductive agent, and a negative electrode binder.

[0098] According to embodiments of this application, the negative electrode active material may include carbon-based materials, silicon-based materials, tin-based materials, etc.

[0099] According to embodiments of this application, the thickener in the negative electrode active material layer includes, but is not limited to, sodium carboxymethyl cellulose.

[0100] According to embodiments of this application, the negative electrode binder in the negative electrode material layer may include, but is not limited to, at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethyl methacrylate (PMAA), and carboxymethyl chitosan (CMCS).

[0101] According to embodiments of this application, the negative electrode conductive agent in the negative electrode material layer may include, but is not limited to, at least one of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0102] In some embodiments, the separator may be a separator known in the art that can be used in lithium batteries and is stable to the electrolyte used, such as a polyethylene separator, a polypropylene separator, a polyethylene / polypropylene composite separator, etc.

[0103] A fifth aspect of this application provides a battery pack comprising the battery described above. All features and advantages of this battery pack are consistent with those of the battery described above, and will not be repeated here.

[0104] It is understood that the battery pack can be a battery module, a battery pack, etc. Specifically, the specific structure of the battery module and battery pack can be found in conventional technologies in this field, and will not be detailed here.

[0105] A sixth aspect of this application provides an electrical device comprising the aforementioned lithium battery or battery pack. All features and advantages of this electrical device are consistent with those of the aforementioned lithium battery and battery pack, and will not be repeated here.

[0106] It is understood that there are no particular restrictions on the specific type of electrical device, and it can be any device that uses a battery as a power source or energy storage unit. As examples, electrical devices include, but are not limited to, electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, etc.), mobile terminals (such as mobile phones, laptops, game consoles, wearable devices, etc.), drones, aerospace equipment, satellites, ships, energy storage systems, etc.

[0107] It is understood that, in addition to the lithium battery or battery pack mentioned above, the electrical device also includes necessary structures and components, all of which can be made with reference to conventional technologies. For example, an electric vehicle may include a body, chassis, tires, navigation system, radar system, steering system, braking system, lubrication system, cooling system, driving system, etc., which will not be described in detail here.

[0108] The embodiments of this application are described in detail below.

[0109] Example 1 Preparation of electrolyte additives: 1. Under nitrogen protection, the chloro derivative R1 (R1 is formula 2a) and thiourea were added to a three-necked flask containing ethanol, wherein the molar ratio of R1 chloro derivative, thiourea and ethanol was 1:1.05:16. The mixture was heated to reflux at 100°C for 2 hours. After the reaction was complete, the ethanol was evaporated to dryness, and the mixture was washed three times with diethyl ether. The result was obtained by evaporation to dryness, yielding R1 substituted isothiourea (R1 is formula 2a). 2. Under an ice-water bath at 0°C, R1-substituted isothiourea (R1 is formula 2a) was dissolved in a single-necked flask containing distilled water and acetonitrile, wherein the molar ratio of R1-substituted isothiourea, distilled water, and acetonitrile was 1:10:80, and stirred until completely dissolved. Tert-butyl hypochlorite and acetonitrile were mixed and dissolved in a molar ratio of 10:80 (where the molar ratio of R1-substituted isothiourea and tert-butyl hypochlorite was 1:1). Under an ice-water bath at 0°C, the tert-butyl hypochlorite solution was added dropwise to the single-necked flask at a rate of 20 drops / min. After the addition was complete, stirring was continued for 1 hour, then the temperature was raised to 25°C (room temperature), and the reaction was stirred for 18 hours. The acetonitrile was then removed by rotary evaporation, and the solution was washed three times with diethyl ether. The clear solution after washing was collected and evaporated to dryness to obtain R1-substituted thiocyanate chloride (R1 is formula 2a). 3. Under nitrogen protection, R1-substituted thiocyanate chloride (R1 is of formula 2a) was dissolved in acetonitrile. After complete dissolution, K2CO3 was added, and the mixture was stirred until homogeneous to obtain a mixed solution. The molar ratio of R1-substituted thiocyanate chloride (R1 is selected from the structure of formula 2a), K2CO3, and acetonitrile was 1:1.5:20. Then, an acetonitrile solution containing R2-substituted sulfonamide (R2 is -CF3) (where the molar ratio of R2-substituted sulfonamide to acetonitrile was 1.05:10, and the molar ratio of R2-substituted sulfonamide to R1-substituted thiocyanate chloride was 1:1) was added dropwise to the above mixed solution at a rate of 20 drops / min, and the reaction was stirred at room temperature (25°C) for 36 h. After the reaction was completed, the reaction solution was filtered, and the filtrate was concentrated by rotary evaporation. The obtained solid was washed with diethyl ether for 10 min to remove residual unreacted reactants. The solid was filtered, collected, and dried to obtain the potassium disulfonamide disulfonamide. 4. Dissolve the disubstituted sulfonamide potassium salt in acetonitrile at a molar ratio of 1:30 to obtain a potassium salt solution; dissolve lithium tetrafluoroborate in acetonitrile at a molar ratio of 1:30 to obtain a lithium salt solution; add the lithium salt solution dropwise to the above potassium salt solution at a rate of 20 drops / min under an ice-water bath at 0°C, with a molar ratio of lithium tetrafluoroborate to disubstituted sulfonamide potassium salt of 1:4. First, react under an ice-water bath at 0°C for 1 hour, then react at room temperature (25°C) for 16 hours. Centrifuge the reaction solution, collect the supernatant, evaporate to obtain a concentrated solution, add diethyl ether to the concentrated solution, and a white solid precipitates. Centrifuge the white solid, discard the supernatant, and the obtained white solid is the disubstituted sulfonamide lithium salt, i.e., compound 1a, and its NMR characterization results are as follows. Figure 1 As shown; Electrolyte preparation: Under argon protection and in a glove box (H2O < 0.01 ppm, O2 < 0.01 ppm), 1 mol of the electrolyte salt LiFSI (lithium bisfluorosulfonyl imide) and 0.05 mol of the electrolyte additive shown in Formula 1a were measured and then added to the organic solvent THF (tetrahydrofuran) (THF solvent volume is in L, i.e., when the amount of lithium salt is 1 mol, the amount of THF is 1 L), and stirred until homogeneous. The concentration of the electrolyte additive in the electrolyte was 0.049 mol / L. Preparation of the positive electrode sheet: Polycrystalline NCM lithium nickel cobalt manganese oxide powder, PVDF binder, and Super P Li conductive carbon black were mixed evenly at a mass ratio of 99:0.5:0.5. The mixture was then placed in a mixing tank, and N-methylpyrrolidone was added. The mixture was initially stirred at 200 r / min for 10 min to prepare the positive electrode slurry mixture. Subsequently, the stirring speed was adjusted to 600 r / min and stirred for 6 h to prepare an NCM811 positive electrode slurry with a solid content of 45%. Using the above positive electrode slurry, with an active material concentration of 20 mg / cm³... 2The loading is coated on single-sided carbon-coated aluminum foil, pre-dried in a forced-air drying oven at 70°C for 1 hour, and then placed in a vacuum drying oven at 100°C for 12 hours; cut into round pieces of the required specifications, which can be used as positive electrode sheets for button cells. Membrane preparation: Commercially available Celgard 2325 membrane was used; Preparation of negative electrode sheet: Lithium metal is used as the negative electrode sheet; Preparation of lithium metal battery: The positive electrode, negative electrode and separator are assembled into an NCM / / Li full cell in a glove box, and then the electrolyte prepared above is injected to obtain a lithium metal battery.

[0110] Example 2 Same as Example 1, except that R1 is Formula 2b and R2 is -CH2CH2F, and the structure of the resulting bis-substituted sulfonylimide lithium salt is shown in Formula 1b.

[0111] Example 3 Same as Example 1, except that R1 is Formula 2c, and the structure of the resulting bisubstituted sulfonylimide lithium salt is shown in Formula 1c.

[0112] Example 4 Same as Example 1, except that: when preparing the electrolyte, the organic solvent used is a mixed solvent composed of THF (tetrahydrofuran) and MeTHF (methyltetrahydrofuran), with a volume ratio of THF to MeTHF of 9:1.

[0113] Example 5 Same as Example 1, except that lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is used as the electrolyte salt when preparing the electrolyte.

[0114] Example 6 Same as Example 1, except that: when preparing the electrolyte, the electrolyte salt is a mixture of lithium bisfluorosulfonylimide (HFSI) and lithium bistrifluoromethanesulfonylimide (LiTFSI) in a molar ratio of 1:1.

[0115] Example 7 Same as Example 1, except that the concentration of electrolyte additive in the electrolyte is 0.01 mol / L.

[0116] Example 8 Same as Example 1, except that the concentration of electrolyte additive in the electrolyte is 0.5 mol / L.

[0117] Comparative Example 1 Same as Example 1, except that the electrolyte additives of this application are not added when preparing the electrolyte.

[0118] Performance testing The lithium metal batteries prepared in Examples 1-8 and Comparative Example 1 were tested for their cycle performance, and the test results are shown in Table 1. The specific method is as follows: At a constant temperature of 25°C, the batteries were activated by constant current charge and discharge at a rate of 0.1C for two cycles within a voltage range of 2.7-4.3V. Subsequently, the batteries were charged and discharged at a rate of 0.3C for 200 cycles.

[0119]

[0120] According to the test results of Examples 1-6 in Table 1, the lithium batteries made with electrolytes containing the electrolyte additives of this application retain a capacity of 84.2%-86.4% and a coulombic efficiency of 98.3%-99.2% after 200 cycles. In contrast, the lithium batteries assembled with electrolytes without the electrolyte additives of this application (Comparative Example 1) retain a capacity of only 76.3% and a coulombic efficiency of only 85% after 200 cycles.

[0121] Furthermore, the capacity retention rate and coulombic efficiency of Examples 7 and 8 in Table 1 are lower than those of Examples 1-6, indicating that both excessively low (Comparative Example 2) and excessively high (Comparative Example 3) concentrations of the electrolyte additive in the electrolyte will reduce the capacity retention rate and coulombic efficiency of the lithium battery, but both are better than those of Comparative Example 1. In summary, the lithium battery made using the electrolyte additive of this application has higher energy utilization and longer lifespan.

[0122] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0123] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0124] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. An electrolyte additive, characterized in that, Including the bisubstituted sulfonylimide lithium salt shown in Formula 1; Formula 1 Wherein, R1 includes any one of Equation 2a, Equation 2b and Equation 2c; R2 includes any one of C1-C3 alkyl groups and C1-C3 haloalkyl groups, wherein the haloalkyl group includes fluoroalkyl groups; Equation 2a Equation 2b Equation 2c.

2. The electrolyte additive according to claim 1, characterized in that, R2 includes at least one of -CH2F, -CF2H, -CF3, -CH2CF3, -CH2CH2F, -CH2CF2H, -CF2CF3, -CH2CF2CF3 and -CF2CF2CF3.

3. The electrolyte additive according to claim 1, characterized in that, The bisubstituted sulfonylimide lithium salt of Formula 1 includes at least one of the following compounds: Formula 1a Formula 1b Equation 1c.

4. A method for preparing the electrolyte additive according to any one of claims 1 to 3, characterized in that, include: Under inert gas protection, the R1 chloro derivative and thiourea are brought into contact in the first solvent and undergo a first reaction to obtain R1 substituted isothiourea; The R1-substituted isothiourea is mixed with a second solvent to obtain a first mixture; The first mixture and tert-butyl hypochlorite were brought into contact in a second solvent and a second reaction was carried out to obtain R1-substituted thioyl chloride; Under inert gas protection, the R1-substituted thiocyanate chloride and potassium source are mixed in a third solvent to obtain a second mixture; The R2-substituted sulfonamide is mixed with the second mixture and a third reaction is carried out to give the disubstituted sulfonylimide potassium salt; The disubstituted sulfonamide potassium salt is mixed with lithium tetrafluoroborate in a fourth solvent and a fourth reaction is carried out. A precipitant is added to precipitate the mixture, thereby obtaining the disubstituted sulfonamide lithium salt shown in Formula 1.

5. The method according to claim 4, characterized in that, At least one of the following conditions must be met: The first solvent includes at least one of ethanol, methanol, and isopropanol; The second solvent includes distilled water and an aprotic solvent, wherein the aprotic solvent includes at least one of acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide; The third solvent includes at least one of acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide; The potassium source includes at least one of potassium carbonate, potassium sulfate, and potassium acetate. The fourth solvent includes at least one of acetonitrile, dimethyl sulfoxide, and N,N-dimethylformamide; The precipitant includes at least one of diethyl ether and petroleum ether.

6. The method according to claim 5, characterized in that, At least one of the following conditions must be met: The molar ratio of the R1 chloro derivative, the thiourea, and the first solvent is 1:0.95-1.2:14-18; The molar ratio of the R1-substituted isothiourea, the distilled water, and the aprotic solvent is 1:8-12:70-90; The molar ratio of the R1-substituted thioyl chloride, the potassium source, and the third solvent is 1:1-2:15-25; The molar ratio of the R2-substituted sulfonamide to the R1-substituted thioacryl chloride is 1:0.9-1.2; The molar ratio of the lithium tetrafluoroborate and the potassium disulfonyl imide is 1:3-5; The molar ratio of the R1-substituted isothiourea and the tert-butyl hypochlorite is 1:0.9-1.

2.

7. The method according to claim 4, characterized in that, At least one of the following conditions must be met: The temperature of the first reaction is 80℃-120℃; The first reaction takes 1-3 hours; The temperature of the second reaction is 0℃-30℃; The second reaction takes 13-32 hours; The temperature of the third reaction is 25℃-30℃; The third reaction takes 30-40 hours; The temperature of the fourth reaction is 0℃-30℃; The fourth reaction takes 10-30 hours.

8. An electrolyte, characterized in that, It includes organic solvents, electrolyte salts, and electrolyte additives according to any one of claims 1 to 3.

9. The electrolyte according to claim 8, characterized in that, The concentration of the electrolyte additive in the electrolyte is 0.02 mol / L to 0.2 mol / L.

10. The electrolyte according to claim 8, characterized in that, At least one of the following conditions must be met: The electrolyte salt includes at least one of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonate, lithium tetrafluoroborate, lithium hexafluorophosphate, lithium bis(oxalate-borate), and lithium bis(oxalate-borate). Preferably, the electrolyte salt includes at least one of the electrolyte salts composed of lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, and lithium bis(trifluoromethanesulfonyl)imide. The concentration of the electrolyte salt in the electrolyte solution is 0.1 mol / L-5 mol / L, preferably 0.5 mol / L-2 mol / L; The organic solvent includes at least one of ethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, 1,3-dioxolane, tetrahydrofuran, methyltetrahydrofuran, methyl formate, methyl acetate, ethyl acetate, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, and methyl ethyl carbonate. Preferably, the organic solvent includes at least one of a mixed solvent composed of tetrahydrofuran, tetrahydrofuran, and methyltetrahydrofuran.

11. A lithium battery, characterized in that, It includes the electrolyte according to any one of claims 8 to 10, the positive electrode, the negative electrode, and the separator.

12. A battery pack, characterized in that, Including the lithium battery as described in claim 11.

13. An electrical appliance, characterized in that, This includes the lithium battery of claim 11 or the battery pack of claim 12.

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