Fluoroalkyl alkyl bis sulfonamide lithium, method for preparing the same, electrolyte and lithium battery

Abstract

This invention relates to the field of electrochemical technology, specifically to fluoroalkylalkylbissulfonamide lithium, its preparation method, electrolyte, and lithium battery. A fluoroalkylalkylbissulfonamide lithium is provided, satisfying the general structural formula shown in Formula IV: [Formula omitted for brevity], where R1 is one or more of monofluoromethyl, difluoromethyl, or trifluoromethyl; n is an integer from 0 to 9; and R2 is selected from C1 to C10 alkyl groups. The fluoroalkylalkylbissulfonamide lithium can synergistically improve battery cycle life, service stability, and high-temperature performance with FEC. A method for preparing fluoroalkylalkylbissulfonamide lithium includes: mixing fluoroalkylsulfonyl chloride, alkylsulfonamide, and a weak base, and carrying out a first reaction to obtain fluoroalkylalkylbissulfonamide potassium; mixing fluoroalkylalkylbissulfonamide potassium and lithium tetrafluoroborate, and carrying out a second reaction to obtain [Foamide]. This significantly shortens the reaction route for preparing bissulfonamide lithium, and offers mild conditions, high yield, low production cost, and simple operation.

Description

Technical Field

[0001] This invention relates to the field of electrochemical technology, specifically to fluoroalkylalkylbissulfonamide lithium, its preparation method, electrolyte, and lithium battery. Background Technology

[0002] Currently, LiPF6 is the most widely used electrolyte lithium salt in industrialized lithium batteries due to its advantages such as high voltage window, moderate conductivity, good solubility and dissociation performance, good film-forming properties, and strong compatibility. However, the poor chemical and electrochemical stability of LiPF6, coupled with the high dosage required for lithium batteries leading to high usage costs, limits its application.

[0003] The negative charge on the central nitrogen atom of the bissulfonamide lithium group can be effectively dispersed and stabilized by two strongly electron-withdrawing sulfonyl groups (-SO2) through resonance, giving it excellent stability. The SNS framework in the molecule also provides good solubility, readily dissolving in organic solvents to form electrolytes suitable for batteries. Furthermore, different substituents on the bissulfonyl group can precisely control the overall chemical properties of the lithium salt; for example, trifluoromethyl groups can further enhance the electron-withdrawing ability of the sulfonyl group, resulting in more complete delocalization of the negative charge and thus higher stability. These characteristics stemming from its molecular structure make it a key material for overcoming current performance bottlenecks in lithium-ion batteries.

[0004] However, the lithium difluoroalkyl sulfonyl imide salts commonly used in related technologies require a large amount of fluorine raw materials for their preparation, resulting in high prices. Furthermore, their high-temperature cycling performance is poor, and their capacity, cycle stability, and lifespan under conditions such as high-temperature storage and high-temperature storage need to be improved. At the same time, lithium difluoroalkyl sulfonyl imide salts such as lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluorosulfonyl imide (LiFSI) will significantly corrode aluminum current collectors under high temperature and high voltage, significantly reducing the battery's lifespan.

[0005] Therefore, there is an urgent need for an electrolyte lithium salt with excellent ionic conductivity, good stability, low corrosivity, simple preparation method, and low cost. Summary of the Invention

[0006] This invention aims to at least partially solve at least one of the technical problems existing in the prior art. To this end, this invention provides a fluoroalkylalkylbissulfonamide-based lithium, its preparation method, electrolyte, and lithium battery. The method involves rapidly reacting fluoroalkylsulfonyl chloride and alkylsulfonamide as raw materials in the presence of a weak base acid-binding agent to generate the intermediate fluoroalkylalkylbissulfonamide potassium. Subsequently, the fluoroalkylalkylbissulfonamide potassium undergoes metal exchange with lithium tetrafluoroborate to obtain fluoroalkylalkylbissulfonamide-based lithium. This preparation method is characterized by mild conditions, high yield, low production cost, and simple operation. The obtained fluoroalkylalkylbissulfonamide-based lithium ions exhibit excellent conductivity, good stability, and good high-temperature performance, showing broad application prospects.

[0007] A first aspect of the present invention provides a fluoroalkylalkylbissulfonamide lithium. According to an embodiment of the present invention, the fluoroalkylalkylbissulfonamide lithium satisfies the general structural formula shown in Formula IV:

[0008]

[0009] Wherein, R1 is one or more of monofluoromethyl, difluoromethyl, or trifluoromethyl; n is an integer from 0 to 9; R2 is selected from C1 to C2. 10 Alkyl groups.

[0010] Using the above technical solution, the fluoroalkyl alkyl bissulfonamide lithium with the structure shown in Formula IV, possessing an asymmetric alkyl chain and a fluorinated alkyl chain, can significantly increase its solubility in conventional electrolyte solvents such as carbonates, avoiding the problems of insufficient concentration in the early stage of cycling and rapid consumption in the later stage caused by the low solubility of traditional additives. At the same time, the asymmetric chain structure can regulate the molecular polarity and spatial conformation, on the one hand promoting its participation in the formation of lithium-ion solvation shell, increasing the lithium-ion transference number, and improving the ion transport efficiency during battery rate charging and discharging. Compared with LIPF6, the fluoroalkyl alkyl bissulfonamide lithium of this invention has better conductivity, which translates into lower battery internal resistance, significantly improving the battery's fast charging and low-temperature performance. Moreover, the introduction of non-fluorinated alkyl groups into its molecule can reduce the amount of expensive fluorine raw materials used, thereby reducing the cost of molecular synthesis. At the same time, it overcomes the defect that LiTFSI will significantly corrode aluminum current collectors under high temperature and high voltage.

[0011] On the other hand, the strong electronegativity of fluoroalkyl chains can enhance the adsorption capacity of molecules on the electrode surface. Combined with the flexibility of alkyl chains, they can help fluoroethylene carbonate (FEC) form a more uniform SEI / CEI film with better mechanical stability during charging, reduce interfacial side reactions, and further enhance the stability of the positive and negative electrode interfaces, thereby simultaneously improving the high-temperature performance and cycle life of the battery.

[0012] According to an embodiment of the present invention, the fluoroalkylalkylbissulfonamide lithium satisfies at least one of the following conditions: R1 is trifluoromethyl; R2 is one or more of methyl, ethyl, and isopropyl.

[0013] According to an embodiment of the present invention, the purity of the fluoroalkylalkylbissulfonamide lithium is ≥99.9%.

[0014] A second aspect of the present invention provides a method for preparing the above-mentioned fluoroalkylalkylbissulfonamide lithium, comprising: A mixture of fluoroalkylsulfonyl chloride, alkylsulfonamide, and a weak base is carried out in the first reaction to obtain fluoroalkylalkylbissulfonamide potassium. A second reaction was carried out by mixing fluoroalkylalkylbissulfonamide potassium and lithium tetrafluoroborate to obtain the fluoroalkylalkylbissulfonamide lithium.

[0015] By employing the above technical solution, the acyl chloride group in fluoroalkyl sulfonyl chloride reacts with the amino group in alkyl sulfonamide in the presence of a weak base as an acid-binding agent to obtain fluoroalkylalkylbissulfonamide potassium, which then undergoes metal ion exchange with lithium tetrafluoroborate to obtain fluoroalkylalkylbissulfonamide lithium. This preparation method significantly shortens the reaction route for preparing bissulfonamide lithium, and is characterized by mild conditions, high yield, low production cost, and simple operation. It overcomes the problems of long reaction time, high temperature or high pressure conditions, and expensive raw materials in related technologies for preparing bissulfonamide lithium, and also significantly improves the yield and product purity. Compared with LIPF6, the obtained fluoroalkylalkylbissulfonamide lithium has better ionic conductivity, resulting in lower battery internal resistance and significantly improved fast charging and low-temperature performance of the battery. Furthermore, the introduction of non-fluorinated alkyl groups into its molecule can reduce the amount of expensive fluorine raw materials used, thereby reducing the cost of molecular synthesis. At the same time, it overcomes the defect that LiTFSI will significantly corrode aluminum current collectors under high temperature and high voltage.

[0016] According to an embodiment of the present invention, the weak base includes at least one of potassium carbonate and potassium bicarbonate, preferably potassium carbonate.

[0017] According to an embodiment of the present invention, the first reaction is carried out in the presence of a first organic solvent.

[0018] According to an embodiment of the present invention, the first organic solvent includes at least one of acetonitrile and dichloromethane. According to an embodiment of the present invention, the molar ratio of the fluoroalkylsulfonyl chloride to the alkylsulfonamide is 1:(0.9 to 1.2), preferably 1:1.

[0019] According to an embodiment of the present invention, the molar ratio of the fluoroalkyl sulfonyl chloride to the weak base is 1:(2-4), preferably 1:3.

[0020] According to an embodiment of the present invention, the reaction temperature of the first reaction is 10℃~30℃, preferably 20℃~25℃; the reaction time of the first reaction is 12h~30h, preferably 12h~20h.

[0021] According to an embodiment of the present invention, the second reaction is carried out in the presence of a second organic solvent, the second organic solvent comprising at least one of acetonitrile and dichloromethane, preferably acetonitrile.

[0022] According to an embodiment of the present invention, the molar ratio of the fluoroalkyl alkyl disulfonamide potassium to lithium tetrafluoroborate is 1:(0.95-1.05), preferably 1:1.

[0023] According to an embodiment of the present invention, the reaction temperature of the second reaction is 10°C to 30°C, preferably 20°C to 25°C; the reaction time of the second reaction is 4h to 16h, preferably 6h to 8h.

[0024] According to an embodiment of the present invention, the fluoroalkyl sulfonyl chloride satisfies the general structural formula shown in Formula I: Wherein, R1 is one or more of monofluoromethyl, difluoromethyl or trifluoromethyl; n is an integer from 0 to 9.

[0025] According to an embodiment of the present invention, Formula I includes at least one of the following structural formulas:

[0026] Where X is a sulfonyl chloride group (-SO2Cl).

[0027] According to an embodiment of the present invention, formula I is At least one of them.

[0028] According to an embodiment of the present invention, the alkylsulfonamide satisfies the general structural formula shown in Formula II: R2 is selected from C1 to C2. 10 Alkyl groups.

[0029] According to an embodiment of the present invention, Formula II includes at least one of the following structural formulas:

[0030] Wherein, Y is a sulfonamide group (-SO2NH2).

[0031] According to an embodiment of the present invention, formula II is: At least one of them.

[0032] A third aspect of the present invention provides an electrolyte comprising the above-described fluoroalkylalkylbissulfonamide lithium or fluoroalkylalkylbissulfonamide lithium prepared by the above-described preparation method.

[0033] According to an embodiment of the present invention, the mass percentage of fluoroalkylalkylbissulfonamide lithium in the electrolyte is 0.01 to 20 wt%.

[0034] Preferably, the mass percentage of the fluoroalkylalkylbissulfonamide lithium is 1 to 5 wt%.

[0035] According to an embodiment of the present invention, the electrolyte further includes FEC.

[0036] In some specific embodiments, the mass fraction of FEC in the electrolyte is 1 to 15 wt%.

[0037] According to an embodiment of the present invention, the mass ratio of the fluoroalkylalkylbissulfonamide lithium to FEC is 1:15 to 20:1; According to an embodiment of the present invention, the electrolyte further includes one or more of lithium salt, additives, and solvents.

[0038] According to an embodiment of the present invention, the lithium salt includes at least one of a first lithium salt and a second lithium salt.

[0039] According to an embodiment of the present invention, the first lithium salt includes one or more of LiPF6, LiBF4, LiAsF6, CF3SO3Li, Li[N(C2F5SO2)2] (LiBETI), and Li[C(C2F5SO2)3], preferably LiPF6.

[0040] According to an embodiment of the present invention, the second lithium salt includes at least one of LiFSI and LiTFSI.

[0041] According to an embodiment of the present invention, the mass percentage of lithium salt in the electrolyte is 10-20 wt%, specifically 10 wt%, 13 wt%, 15 wt%, 18 wt%, 20 wt%, etc.

[0042] According to an embodiment of the present invention, in the electrolyte, the mass percentage of the second lithium salt in the electrolyte is 0 to 3 wt%.

[0043] According to an embodiment of the present invention, the additives include one or more of film-forming aids, conductive aids, flame retardant aids, anti-overcharge aids, stabilizing aids, and multifunctional aids.

[0044] According to an embodiment of the present invention, the mass fraction of the additive is 0.1 to 5 wt% based on the total mass of the electrolyte, and it is necessary to ensure that the synergistic effect between fluoroalkylalkylbissulfonamide lithium and FEC is not impaired.

[0045] According to an embodiment of the present invention, the solvent includes one or more of carbonates, carboxylic esters, ethers, sulfones, and ketones.

[0046] According to an embodiment of the present invention, the carbonate includes one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), and propylene carbonate (PC), preferably one or more of EC, DEC, and EMC.

[0047] According to an embodiment of the present invention, the total amount of DEC and EMC used is in a volume ratio of 2:8 to 8:2 with respect to EC.

[0048] According to an embodiment of the present invention, the method for preparing the electrolyte includes: dissolving lithium salt, fluoroalkylalkylbissulfonamide lithium, and additives in an organic solvent in an argon-filled glove box, and stirring to obtain the electrolyte.

[0049] A fourth aspect of the present invention provides a lithium battery. According to an embodiment of the present invention, the lithium battery includes the electrolyte described above.

[0050] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. This invention provides a fluoroalkylalkylbissulfonamide lithium, its preparation method, electrolyte, and lithium battery. By replacing part of LiFSI or LiTFSI with the functional additive fluoroalkylalkylbissulfonamide lithium, and forming a synergistic effect with FEC, it can reduce the corrosion of aluminum foil current collector by LiFSI and LiTFSI in the system, reduce battery side reactions, and optimize the film quality of electrode / electrolyte interface. This significantly improves the overall performance of the battery under high temperature storage, high temperature storage, and high temperature cycling conditions, effectively suppresses the problems of battery capacity decay and increased internal resistance under high temperature environment, and extends the cycle life and service stability of the battery when used at high temperature. 2. The fluoroalkylalkylbissulfonamide lithium described in this invention can optimize the battery electrode / electrolyte interface structure, form a stable and dense interface protective film, reduce the occurrence of interface side reactions, significantly improve the battery interface stability, and further reduce the safety risks (such as thermal runaway, gas expansion, etc.) caused by interface failure during battery charging, discharging and storage, thus comprehensively improving the safety of battery use. 3. The preparation method described in this invention has mild conditions, high yield, low production cost, and simple operation. The obtained fluoroalkyl alkyl bissulfonamide lithium-ion has excellent conductivity, good stability, and good high-temperature performance. It is compatible with existing battery production processes and has strong compatibility, which is conducive to large-scale application. Attached Figure Description

[0051] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the preparation examples taken in conjunction with the following drawings, wherein: Figure 1 The intermediate 1 prepared in Example 1 of this invention 1 H NMR spectrum; Figure 2 The intermediate 1 prepared in Example 1 of this invention 19 F NMR spectrum; Figure 3 The trifluoromethylmethylbissulfonamide lithium prepared in Example 1 of this invention 1 H NMR spectrum; Figure 4 The trifluoromethylmethylbissulfonamide lithium prepared in Example 1 of this invention 19 F NMR spectrum; Figure 5 Intermediate 2 prepared in Example 2 of the present invention 1 H NMR spectrum; Figure 6 Intermediate 2 prepared in Example 2 of the present invention 19 F NMR spectrum; Figure 7 The trifluoromethylethylbissulfonamide lithium prepared in Example 2 of this invention 1 H NMR spectrum; Figure 8 The trifluoromethylethylbissulfonamide lithium prepared in Example 2 of this invention 19 F NMR spectrum; Figure 9 Intermediate 3 prepared in Example 3 of the present invention 1 H NMR spectrum; Figure 10 Intermediate 3 prepared in Example 3 of the present invention 19 F NMR spectrum; Figure 11 The trifluoromethylisopropylbissulfonamide lithium prepared in Example 3 of this invention 1 H NMR spectrum; Figure 12 The trifluoromethylisopropylbissulfonamide lithium prepared in Example 3 of this invention 19 F NMR spectrum. Detailed Implementation

[0052] The preparation examples of the present invention are described in detail below. The preparation examples described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0053] It should be noted that 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 indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0055] In this document, the terms “comprising” or “including” are open-ended expressions, meaning that they include the contents specified in this invention, but do not exclude other aspects.

[0056] In this document, the terms “optionally,” “optionally,” or “optionally” generally refer to an event or condition that may, but may not, occur, and the description includes both cases in which the event or condition occurs and cases in which the event or condition does not occur.

[0057] A first aspect of the present invention provides a fluoroalkylalkylbissulfonamide lithium. According to an embodiment of the present invention, the fluoroalkylalkylbissulfonamide lithium satisfies the general structural formula shown in Formula IV:

[0058] Wherein, R1 is one or more of monofluoromethyl, difluoromethyl, or trifluoromethyl; n is an integer from 0 to 9; R2 is selected from C1 to C2. 10 Alkyl groups.

[0059] Using the above technical solution, the fluoroalkyl alkyl bissulfonamide lithium with the structure shown in Formula IV, possessing an asymmetric alkyl chain and a fluorinated alkyl chain, can significantly increase its solubility in conventional electrolyte solvents such as carbonates, avoiding the problems of insufficient concentration in the early stage of cycling and rapid consumption in the later stage caused by the low solubility of traditional additives. At the same time, the asymmetric chain structure can regulate the molecular polarity and spatial conformation, on the one hand promoting its participation in the formation of lithium-ion solvation shell, increasing the lithium-ion transference number, and improving the ion transport efficiency during battery rate charging and discharging. Compared with LIPF6, the fluoroalkyl alkyl bissulfonamide lithium of this invention has better conductivity, which translates into lower battery internal resistance, significantly improving the battery's fast charging and low-temperature performance. Moreover, the introduction of non-fluorinated alkyl groups into its molecule can reduce the amount of expensive fluorine raw materials used, thereby reducing the cost of molecular synthesis. At the same time, it overcomes the defect that LiTFSI will significantly corrode aluminum current collectors under high temperature and high voltage.

[0060] On the other hand, the strong electronegativity of fluoroalkyl chains can enhance the adsorption capacity of molecules on the electrode surface. Combined with the flexibility of alkyl chains, they can help fluoroethylene carbonate (FEC) form a more uniform SEI / CEI film with better mechanical stability during charging, reduce interfacial side reactions, and further enhance the stability of the positive and negative electrode interfaces, thereby simultaneously improving the high-temperature performance and cycle life of the battery.

[0061] For example, the value of n can be 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, etc.

[0062] According to an embodiment of the present invention, the fluoroalkylalkylbissulfonamide lithium satisfies at least one of the following conditions: R1 is trifluoromethyl; R2 is one or more of methyl, ethyl, and isopropyl.

[0063] The above technical solution is beneficial to further improve the ionic conductivity of fluoroalkyl alkyl disulfonamide lithium, avoid corrosion of aluminum current collectors, and improve the battery's fast charging and low-temperature performance, high-temperature performance and cycle life.

[0064] According to an embodiment of the present invention, the fluoroalkylalkylbissulfonamide lithium has a purity of ≥99.9%. Using fluoroalkylalkylbissulfonamide lithium of this purity as an electrolyte additive helps to meet the requirements for use in lithium battery electrolytes and avoids the negative impact of impurity ions on battery performance.

[0065] A second aspect of the present invention provides a method for preparing fluoroalkylalkylbissulfonamide lithium, comprising: A mixture of fluoroalkylsulfonyl chloride, alkylsulfonamide, and a weak base is carried out in the first reaction to obtain fluoroalkylalkylbissulfonamide potassium. A second reaction was carried out by mixing fluoroalkylalkylbissulfonamide potassium and lithium tetrafluoroborate to obtain the fluoroalkylalkylbissulfonamide lithium.

[0066] By employing the above technical solution, the acyl chloride group in fluoroalkyl sulfonyl chloride reacts with the amino group in alkyl sulfonamide in the presence of a weak base as an acid-binding agent to obtain fluoroalkylalkylbissulfonamide potassium, which then undergoes metal ion exchange with lithium tetrafluoroborate to obtain fluoroalkylalkylbissulfonamide lithium. This preparation method significantly shortens the reaction route for preparing bissulfonamide lithium, and is characterized by mild conditions, high yield, low production cost, and simple operation. It overcomes the problems of long reaction time, high temperature or high pressure conditions, and expensive raw materials in related technologies for preparing bissulfonamide lithium, and also significantly improves the yield and product purity. Compared with LIPF6, the obtained fluoroalkylalkylbissulfonamide lithium has better ionic conductivity, resulting in lower battery internal resistance and significantly improved fast charging and low-temperature performance of the battery. Furthermore, the introduction of non-fluorinated alkyl groups into its molecule can reduce the amount of expensive fluorine raw materials used, thereby reducing the cost of molecular synthesis. At the same time, it overcomes the defect that LiTFSI will significantly corrode aluminum current collectors under high temperature and high voltage.

[0067] According to an embodiment of the present invention, the weak base includes at least one of potassium carbonate and potassium bicarbonate, preferably potassium carbonate. This is advantageous in reducing side reactions while ensuring the acid binding rate.

[0068] According to an embodiment of the present invention, the first reaction is carried out in the presence of a first organic solvent.

[0069] According to an embodiment of the present invention, the first organic solvent includes at least one of acetonitrile and dichloromethane. This facilitates the reduction of side reactions such as hydrolysis and condensation, thereby improving product purity and yield.

[0070] According to an embodiment of the present invention, the molar ratio of the fluoroalkylsulfonyl chloride to the alkylsulfonamide is 1:(0.9 to 1.2), preferably 1:1. Exemplarily, the molar ratio of the fluoroalkylsulfonyl chloride to the alkylsulfonamide can be 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, etc. This is beneficial to product purity and avoids problems such as low yield and difficult post-processing caused by large amounts of unreacted raw materials remaining.

[0071] According to an embodiment of the present invention, the molar ratio of the fluoroalkyl sulfonyl chloride to the weak base is 1:(2-4), preferably 1:3. Exemplarily, the molar ratio of the fluoroalkyl sulfonyl chloride to the weak base can be 1:2, 1:2.5, 1:3, 1:3.5, 1:4, etc. This helps to reduce hydrolysis byproducts while ensuring the reaction rate, avoids the need for additional water washing steps in the post-treatment stage, and simplifies the process.

[0072] According to an embodiment of the present invention, the reaction temperature of the first reaction is 10℃ to 30℃, preferably 20℃ to 25℃; specifically, such as 10℃, 12℃, 15℃, 18℃, 20℃, 22℃, 25℃, 28℃, 30℃, etc. This is beneficial for maintaining a high reaction rate while reducing side reactions and improving product purity.

[0073] According to an embodiment of the present invention, the reaction time of the first reaction is 12h to 30h, preferably 12h to 20h; specifically, such as 12h, 15h, 18h, 20h, 22h, 25h, 28h, 30h, etc. This is beneficial for improving the conversion rate of raw materials and minimizing by-products.

[0074] According to an embodiment of the present invention, the second reaction is carried out in the presence of a second organic solvent, which includes at least one selected from acetonitrile and dichloromethane, preferably acetonitrile. This is advantageous for increasing the metal ion exchange rate while simultaneously resulting in larger KCl crystals, facilitating subsequent impurity removal.

[0075] According to an embodiment of the present invention, the molar ratio of the fluoroalkyl alkyl disulfonamide potassium to lithium tetrafluoroborate is 1:(0.95-1.05), preferably 1:1; specifically, such as 1:0.95, 1:0.98, 1:1, 1:1.03, 1:1.05, etc. This is beneficial for reducing K. + There are no residues, and the required product purity can be achieved with simple post-processing.

[0076] According to an embodiment of the present invention, the reaction temperature of the second reaction is 10°C to 30°C, preferably 20°C to 25°C; specifically, such as 10°C, 12°C, 15°C, 18°C, 20°C, 22°C, 25°C, 28°C, 30°C, etc. Therefore, K can be made... + Rapid desolvation reduces byproducts, which helps improve reaction efficiency and product purity, and simplifies the preparation process.

[0077] According to an embodiment of the present invention, the reaction time of the second reaction is 4h to 16h, preferably 6h to 8h; specifically, such as 4h, 5h, 6h, 7h, 8h, 10h, 12h, 14h, 16h, etc. This allows for complete exchange of metal ions, improving the conversion rate.

[0078] In some embodiments, the preparation method is carried out entirely under dry conditions.

[0079] According to an embodiment of the present invention, the preparation method further includes crystallization purification of fluoroalkylalkylbissulfonamide potassium.

[0080] According to an embodiment of the present invention, the crystallization purification includes: filtering after the first reaction, concentrating the filtrate by rotary evaporation, crystallizing, filtering, and obtaining purified fluoroalkylalkylbissulfonamide potassium.

[0081] By employing the above technical solution, the intermediate fluoroalkylalkylbissulfonamide potassium can be separated from the reaction solution by taking advantage of the high solubility of fluoroalkylalkylbissulfonamide potassium and impurities in acetonitrile, thus obtaining a relatively pure intermediate product.

[0082] According to an embodiment of the present invention, the preparation method further includes crystallization and purification of fluoroalkylalkylbissulfonamide lithium.

[0083] According to an embodiment of the present invention, the crystallization purification includes: filtering the reaction solution after the second reaction, evaporating the filtrate to dryness, adding a small amount of diethyl ether to dissolve it, slowly adding dichloromethane, crystallizing, filtering, and obtaining purified fluoroalkylalkylbissulfonamide lithium.

[0084] By adopting the above technical solution, the poor solubility of fluoroalkylalkylbissulfonamide lithium in dichloromethane can be utilized to separate the product fluoroalkylalkylbissulfonamide lithium from the reaction solution, thereby obtaining a relatively pure product.

[0085] Therefore, the preparation method described in this invention has mild conditions, high yield, low production cost, simple operation, and is easy to implement, which is conducive to large-scale industrial use.

[0086] According to an embodiment of the present invention, the fluoroalkyl sulfonyl chloride satisfies the general structural formula shown in Formula I: Wherein, R1 is one or more of monofluoromethyl, difluoromethyl or trifluoromethyl; n is an integer from 0 to 9.

[0087] According to an embodiment of the present invention, Formula I includes at least one of the following structural formulas:

[0088] Where X is a sulfonyl chloride group (-SO2Cl).

[0089] According to an embodiment of the present invention, formula I is At least one of them.

[0090] According to an embodiment of the present invention, the alkylsulfonamide satisfies the general structural formula shown in Formula II: R2 is selected from C1 to C2. 10 Alkyl groups.

[0091] According to an embodiment of the present invention, Formula II includes at least one of the following structural formulas:

[0092] Wherein, Y is a sulfonamide group (-SO2NH2).

[0093] According to an embodiment of the present invention, formula II is: At least one of them.

[0094] According to the method of the present invention, the preparation method uses fluoroalkyl sulfonyl chloride of Formula I and alkyl sulfonamide of Formula II as raw materials to carry out a first reaction to obtain fluoroalkyl alkyl disulfonamide potassium of Formula III; the fluoroalkyl alkyl disulfonamide potassium undergoes a second reaction with lithium tetrafluoroborate to exchange metal ions to obtain fluoroalkyl alkyl disulfonamide lithium of Formula IV, and the reaction formula is as follows:

[0095] Wherein, R1 is one or more of monofluoromethyl, difluoromethyl, or trifluoromethyl; n is an integer from 0 to 9; R2 is selected from C1 to C2. 10 Alkyl groups.

[0096] A third aspect of the present invention provides an electrolyte comprising the above-described fluoroalkylalkylbissulfonamide lithium or fluoroalkylalkylbissulfonamide lithium prepared by the above-described preparation method.

[0097] By adopting the above technical solution, the introduction of the fluoroalkyl alkyl bissulfonamide lithium as a functional additive into the electrolyte can effectively improve the stability of the electrolyte under high temperature conditions and form a stable SEI / CEI film, promoting rapid lithium ion transport and uniform lithium deposition. This can inhibit electrolyte decomposition and reduce the consumption of active materials, thereby improving the safety of the secondary battery. The addition of the fluoroalkyl alkyl bissulfonamide lithium can also replace part of LiFSI or LiTFSI, achieving equal or improved battery performance, and solving problems such as high LiFSI or LiTFSI addition, high cost, easy corrosion of aluminum foil, and insignificant improvement in low-temperature cycling performance in related electrolytes.

[0098] According to an embodiment of the present invention, the mass percentage of fluoroalkyl alkyl disulfonamide lithium in the electrolyte is 0.01–20 wt%. Exemplary values ​​can be 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 13 wt%, 15 wt%, 18 wt%, 20 wt%, etc., or any range between any two of the above values. When the content of fluoroalkyl alkyl disulfonamide lithium is less than 0.01 wt%, it is difficult for it to fully participate in the ion solvation and interfacial film formation process, and the synergistic effect with FEC is not obvious; when the content is higher than 20 wt%, excess fluoroalkyl alkyl disulfonamide lithium is easily deposited on the electrode surface, leading to increased internal resistance.

[0099] Preferably, the mass percentage of the fluoroalkyl alkyl disulfonamide lithium is 1 to 5 wt%; thus, it can replace 1 to 100 wt% of the conventional content of LiFSI or LiTFSI in the electrolyte, that is, the fluoroalkyl alkyl disulfonamide lithium of the present invention within the above-mentioned content range can partially or completely replace the LiFSI or LiTFSI component in the relevant electrolyte without reducing the relevant performance of the battery, and can achieve the replacement or improvement of battery performance.

[0100] It should be noted that the present invention does not particularly limit the method of adding the fluoroalkylalkylbissulfonamide lithium. For example, the electrolyte can be obtained by adding fluoroalkylalkylbissulfonamide lithium to a commercially available electrolyte, or the electrolyte can be prepared entirely in-house. Therefore, all electrolytes related to the fluoroalkylalkylbissulfonamide lithium described in this invention are within the scope of protection.

[0101] According to an embodiment of the present invention, the electrolyte further includes FEC.

[0102] By adopting the above technical solution, the fluoroalkyl alkyl bissulfonamide lithium and FEC can achieve a synergistic effect through the following processes: In the electrolyte system, fluoroalkyl alkyl bissulfonamide lithium participates in the solvation structure of lithium ions, increasing the lithium ion transference number; during charging, fluoroalkyl alkyl bissulfonamide lithium can balance the charge distribution at the negative electrode interface, jointly form a film with FEC, and make the SEI film composition distribution more uniform, the film layer thinner, and more stable; on the positive electrode side, because the decomposition voltage of fluoroalkyl alkyl bissulfonamide lithium is ≥3.9V vs Li / Li + Therefore, a high-voltage positive electrode can participate in the positive electrode CEI film formation process, making the positive electrode CEI film formation more stable. When the voltage is ≥4.5V vs Li / Li +FEC assists in film formation, with a more significant effect. Therefore, when selecting different positive and negative electrode materials, within different voltage ranges, fluoroalkyl alkyl bissulfonamide lithium and FEC can synergistically optimize the film formation of positive and negative electrodes and the high lithium-ion transference number of the electrolyte, thereby increasing battery stability, charge-discharge rate, energy efficiency, and high-temperature performance.

[0103] In some specific embodiments, the mass fraction of FEC in the electrolyte is 1–15 wt%. As a synergistic component, an FEC mass fraction below 1 wt% may lead to insufficient film-forming assistance and poor SEI / CEI film stability; a mass fraction above 15 wt% can easily cause an increase in electrolyte viscosity, affecting ion migration rate. For example, the mass fraction of FEC can be selected from 1 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, and any range between two of the above values.

[0104] According to an embodiment of the present invention, the mass ratio of the fluoroalkyl alkyl disulfonamide lithium to FEC is 1:15 to 20:1, specifically such as 1:15, 1:10, 1:5, 1:3, 1:1, 3:1, 5:1, 10:1, 15:1, 20:1, etc.

[0105] According to an embodiment of the present invention, the electrolyte further includes one or more of lithium salt, additives, and solvents.

[0106] It should be noted that lithium salts provide migratable lithium ions and transfer charge between the positive and negative electrodes, thereby enabling the battery to charge and discharge cycles. This invention does not impose any particular limitation on the lithium salts used; common lithium salts found in electrolytes are suitable for this invention.

[0107] According to an embodiment of the present invention, the lithium salt includes at least one of a first lithium salt and a second lithium salt.

[0108] According to an embodiment of the present invention, the first lithium salt includes one or more of LiPF6, LiBF4, LiAsF6, CF3SO3Li, Li[N(C2F5SO2)2] (LiBETI), and Li[C(C2F5SO2)3], preferably LiPF6.

[0109] According to an embodiment of the present invention, the second lithium salt includes at least one of LiFSI and LiTFSI.

[0110] According to an embodiment of the present invention, the mass percentage of lithium salt in the electrolyte is 10-20 wt%, specifically 10 wt%, 13 wt%, 15 wt%, 18 wt%, 20 wt%, etc.

[0111] According to an embodiment of the present invention, in the electrolyte, the mass percentage of the second lithium salt in the electrolyte is 0 to 3 wt%, specifically such as 0, 0.5 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, etc.

[0112] By adopting the above technical solution, the fluoroalkylalkylbissulfonamide lithium can be used as a functional electrolyte additive to effectively reduce the amount of the second lithium salt by replacing it, and significantly reduce the corrosion of the aluminum current collector.

[0113] It should be noted that traditional commercial electrolytes contain as much as 3 to 4.5 wt% LiFSI or LiTFSI, which is expensive. The fluoroalkylalkylbissulfonamide lithium, as an electrolyte additive, can reduce the amount of LiFSI or LiTFSI used, avoid aluminum foil corrosion caused by excessive LiFSI or LiTFSI under high voltage, improve the electrochemical performance of the electrolyte, optimize the electrolyte electrode interface and reduce its impedance, improve the battery charge-discharge performance and cycle stability, and reduce costs.

[0114] It should be noted that the present invention does not impose any particular limitations on the additives mentioned above; any additive that does not impair the technical effect of the present invention is applicable to the present invention.

[0115] According to an embodiment of the present invention, the additives include one or more of film-forming aids, conductive aids, flame retardant aids, anti-overcharge aids, stabilizing aids, and multifunctional aids.

[0116] In some embodiments, the film-forming aid includes VC; the conductive aid includes carbon nanotubes; the flame retardant aid includes phosphate ester compounds; the anti-overcharge aid includes vinyl sulfate (DTD); and the stabilizing aid includes metal ion chelating agents.

[0117] According to an embodiment of the present invention, based on the total mass of the electrolyte, the mass fraction of the additive is 0.1–5 wt%, and it must be ensured that the synergistic effect between fluoroalkyl alkyl disulfonamide lithium and FEC is not impaired. For example, the mass fraction of the additive can be 0.1 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, etc.

[0118] It should be noted that the present invention does not impose any particular restrictions on the selected solvent. Any conventional lithium battery electrolyte solvent that does not impair the technical effect of the present invention is applicable to the present invention.

[0119] According to an embodiment of the present invention, the solvent includes one or more of carbonates, carboxylic esters, ethers, sulfones, and ketones.

[0120] According to an embodiment of the present invention, the carbonate includes one or more of ethylene carbonate (EC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), and propylene carbonate (PC), preferably one or more of EC, DEC, and EMC.

[0121] According to an embodiment of the present invention, the total amount of DEC and EMC used is in a volume ratio of 2:8 to 8:2 with respect to EC; specifically, such as 2:8, 2:6, 2:4, 2:2, 2:1, 1:2, 2:2, 4:2, 6:2, 8:2, etc.

[0122] In some embodiments, the volume ratio of EC, DEC and EMC is EC:DEC:EMC = 1:1:1.

[0123] According to an embodiment of the present invention, the method for preparing the electrolyte includes: dissolving lithium salt, fluoroalkylalkylbissulfonamide lithium, and additives in an organic solvent in an argon-filled glove box, and stirring to obtain the electrolyte.

[0124] A fourth aspect of the present invention provides a lithium battery. According to an embodiment of the present invention, the lithium battery includes the above-described electrolyte. This is advantageous for improving the ionic conductivity and cycle stability of the lithium battery, increasing its service life, and reducing production costs.

[0125] According to an embodiment of the present invention, the lithium battery includes a positive electrode, a negative electrode, a separator, and an electrolyte.

[0126] According to an embodiment of the present invention, the positive electrode includes a positive current collector and a positive active material layer coated on at least one side surface of the positive current collector, the positive active material layer including a positive active material; the negative electrode includes a negative current collector and a negative active material layer located on the negative current collector, the negative active material layer including a negative active material.

[0127] It should be noted that the present invention does not impose any particular limitation on the type of positive electrode current collector, which can be any known material suitable for use as a positive electrode current collector.

[0128] In one embodiment, the positive electrode current collector includes metallic materials such as aluminum, stainless steel, nickel plating, titanium, and tantalum, as well as carbon materials such as carbon cloth and carbon paper. Preferably, the positive electrode current collector is a metallic material.

[0129] It should be noted that the present invention does not impose any particular limitation on the positive electrode active material. Any conventional positive electrode active material used in lithium batteries can be used in the present invention.

[0130] According to an embodiment of the present invention, the positive electrode active material includes at least one of lithium transition metal composite oxide material or surface-modified lithium transition metal composite oxide material.

[0131] According to an embodiment of the present invention, the lithium transition metal composite oxide material includes one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, and nickel cobalt manganese ternary oxide.

[0132] In one embodiment, the positive electrode active material includes one or more of lithium manganese oxide, lithium iron phosphate, lithium iron manganese phosphate, nickel-cobalt-manganese ternary materials, lithium cobalt oxide, lithium-rich manganese materials, and nickel-manganese oxide materials.

[0133] It should be noted that this invention does not impose any particular limitation on the negative electrode current collector, as long as it can achieve the purpose of this application. For example, it can be copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or a composite current collector, etc. This invention does not impose any particular limitation on the negative electrode active material; any conventional negative electrode active material used in lithium batteries can be used in this invention.

[0134] According to embodiments of the present invention, the negative electrode active material includes lithium metal, natural graphite, artificial graphite, mesophase microcarbon spheres (MCMB), hard carbon, soft carbon, silicon, silicon-carbon composites, Li-Sn alloys, Li-Sn-O alloys, Sn, SnO, SnO2, and spinel-type lithium titanate (Li4Ti5O). 12 One or more of Li-Al alloys and Li-Si alloys.

[0135] In one embodiment, the negative electrode active material is selected from at least one of artificial graphite and metallic lithium.

[0136] According to an embodiment of the present invention, the negative electrode sheet further includes a negative electrode current collector. The present invention does not impose any particular limitation on the negative electrode current collector, as long as it can achieve the purpose of this application, such as one or more of copper foil, copper alloy foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, or composite current collectors.

[0137] According to an embodiment of the present invention, the positive electrode active material layer and the negative electrode active material layer further include a conductive agent and a binder.

[0138] According to an embodiment of the present invention, the conductive agent includes at least one of conductive carbon black, conductive graphite, conductive carbon fiber, carbon nanotubes, metal powder, and carbon fiber.

[0139] Furthermore, the conductive carbon black includes at least one of acetylene black and Ketjen black.

[0140] According to an embodiment of the present invention, the adhesive comprises at least one selected from polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, sodium carboxymethyl cellulose, styrene-butadiene latex, polytetrafluoroethylene, and polyethylene oxide.

[0141] According to an embodiment of the present invention, the separator is spaced between the positive electrode and the negative electrode.

[0142] It should be noted that the material and shape of the diaphragm described in this invention are not particularly limited as long as it is stable in the electrolyte and has excellent liquid retention. For example, it can be a porous polyolefin sheet or nonwoven fabric, or a porous polyolefin sheet or nonwoven fabric with various organic or inorganic materials coated on its surface to enhance wettability and mechanical properties; the polyolefin is at least one of polyethylene, polypropylene, polybutene, polyisobutylene, and ethylene-α-olefin copolymer.

[0143] In one embodiment, the membrane comprises a polyolefin membrane coated with Al2O3 on one side.

[0144] According to embodiments of the present invention, the lithium battery category includes one or more of button batteries, pouch batteries, or cylindrical batteries.

[0145] The present invention will be explained below with reference to preparation examples. Those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the examples, they are performed according to the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0146] The electrolytes in the following examples and comparative examples were prepared under the following conditions: in a glove box filled with argon gas of 99.999% purity, the moisture content in the glove box was less than 0.1 ppm, and the temperature was room temperature.

[0147] Preparation Example 1: Preparation of Trifluoromethylmethylbissulfonamide lithium (Compound 1)

[0148] S1. Add 62.5 mmol of methanesulfonamide and 60 mL of acetonitrile to a three-necked flask and mix to dissolve. Then add 187.5 mmol of potassium carbonate, ventilate, and cool to 0°C. Slowly add 20 mL of acetonitrile solution containing 62.5 mmol of trifluoromethanesulfonyl chloride. After the addition is complete, heat to room temperature and stir for 16 h. After the reaction is complete, filter the reaction solution directly. Concentrate the filtrate by rotary evaporation until a large amount of solid precipitates. Filter the solution and dry the filter cake under vacuum at 100°C to obtain 6.0 g of white intermediate 1, with a yield of 38.2%. S2. Add 60 mL of acetonitrile to a three-necked flask containing 21.8 mmol of intermediate 1 and mix and dissolve. Then add 20 mL of acetonitrile solution containing 21.8 mmol of lithium tetrafluoroborate. Stir the reaction at 25 °C for 6 h. Filter the reaction solution, evaporate the filtrate to dryness, add a small amount of diethyl ether to dissolve, and slowly add dichloromethane while stirring until a large amount of solid precipitates. Filter, dry under vacuum at 100 °C to obtain 4.8 g of white solid, yield 94.5%.

[0149] Mass spectrometry (MS / S) measurements were performed on intermediate 1 and the product lithium trifluoromethylmethylbissulfonamide obtained in this preparation example. The MS / S result for intermediate 1 was 264.91 [M], and the MS / S result for the product lithium trifluoromethylmethylbissulfonamide was 232.96 [M]. The mass decreased by 32 Da from 264.91 for the intermediate to 232.91 for the product; this 32 Da corresponds precisely to the relative mass difference between K+ and Li+, proving that step S2 in this preparation example successfully completed the metal exchange.

[0150] The intermediate 1 and the product trifluoromethylmethylbissulfonamide lithium prepared in this preparation example were subjected to 1H NMR spectroscopy. 1 ¹H NMR (400 MHz, DMSO-d6) and fluorine NMR spectrum 19 F NMR (376 MHz, DMSO-d6) tests were performed, and the results are shown in [reference needed]. Figure 1-4 .Depend on Figure 1-4 As can be seen, the 1H NMR spectrum of intermediate 1 showed a characteristic peak at δ2.87 (s, 3H, CH3), and the fluorine NMR spectrum showed a characteristic peak at δ-77.52 (CF3), proving that the intermediate with the described structure was successfully synthesized; the 1H NMR spectrum of the product showed a characteristic peak at δ2.86 (s, 3H, CH3), and the fluorine NMR spectrum showed a characteristic peak at δ-77.48 (CF3), proving that the trifluoromethylmethylbissulfonamide lithium with the described structure was successfully synthesized.

[0151] Preparation Example 2: Preparation of Trifluoromethylethylbissulfonamide lithium (Compound 2)

[0152] S1. Add 91.7 mmol of ethanesulfonamide and 100 mL of acetonitrile to a three-necked flask and mix to dissolve. Then add 275.2 mmol of potassium carbonate, ventilate, and cool to 0°C. Slowly add 50 mL of acetonitrile solution containing 91.7 mmol of trifluoromethanesulfonyl chloride. After the addition is complete, heat to room temperature and stir for 16 h. After the reaction is complete, filter the reaction solution directly. Concentrate the filtrate by rotary evaporation until a large amount of solid precipitates. Filter the solution and dry the filter cake under vacuum at 100°C to obtain 9.5 g of white intermediate 2, with a yield of 37.1%. S2. Add 100 mL of acetonitrile to a three-necked flask containing 34.0 mmol of intermediate 2 and mix and dissolve. Then add 30 mL of acetonitrile solution containing 34.0 mmol of lithium tetrafluoroborate. Stir the reaction at 25 °C for 6 h. Filter the reaction solution, evaporate the filtrate to dryness, add a small amount of diethyl ether to dissolve, and slowly add dichloromethane under stirring until a large amount of solid precipitates. Filter, dry under vacuum at 100 °C to obtain 7.2 g of white solid, yield 85.6%.

[0153] Mass spectrometry (MS / S) measurements were performed on intermediate 2 and the product lithium trifluoromethylethylbissulfonamide obtained in this preparation example. The MS / S mass spectrometry result for intermediate 2 was 278.92 [M], and the MS / S mass spectrometry result for the product lithium trifluoromethylethylbissulfonamide was 246.98 [M]. The mass decreased by 32 Da from the intermediate to the product; and 32 Da corresponds exactly to the relative mass difference between K+ and Li+, proving that step S2 of this preparation example successfully completed the metal exchange.

[0154] The intermediate 2 and the product trifluoromethylethylbissulfonamide lithium prepared in this preparation example were subjected to 1H NMR spectroscopy. 1 ¹H NMR (400 MHz, DMSO-d6) and fluorine NMR spectrum 19 F NMR (376 MHz, DMSO-d6) tests were performed, and the results are shown in [reference needed]. Figure 5-8 .Depend on Figure 5-8 As can be seen, the 1H NMR spectrum of intermediate 2 showed characteristic peaks at δ3.49-3.44 (m, 2H, CH2) and 1.22 (t, 3H, CH3), and the fluorine NMR spectrum showed a characteristic peak at δ-77.46 (CF3), proving that the intermediate with the described structure was successfully synthesized; the 1H NMR spectrum of the product showed characteristic peaks at δ3.48-3.42 (m, 2H, CH2) and 1.22 (t, 3H, CH3), and the fluorine NMR spectrum showed a characteristic peak at δ-77.47 (CF3), proving that the trifluoromethylethylbissulfonamide lithium with the described structure was successfully synthesized.

[0155] Preparation Example 3: Preparation of Trifluoromethylisopropylbissulfonamide lithium (Compound 3)

[0156] S1. Add 40.6 mmol of isopropyl sulfonamide and 50 mL of acetonitrile to a three-necked flask and mix to dissolve. Then add 121.9 mmol of potassium carbonate, ventilate, and cool to 0°C. Slowly add 20 mL of acetonitrile solution containing 40.6 mmol of trifluoromethanesulfonyl chloride. After the addition is complete, heat to room temperature and stir for 16 h. After the reaction is complete, filter the reaction solution directly. Concentrate the filtrate by rotary evaporation until a large amount of solid precipitates. Filter the solution and dry the filter cake under vacuum at 100°C to obtain 4.2 g of white intermediate 3, with a yield of 37.1%. S2. Add 40 mL of acetonitrile to a three-necked flask containing 14.3 mmol of intermediate 3 and mix to dissolve. Then add 10 mL of acetonitrile solution containing 14.3 mmol of lithium tetrafluoroborate. Stir the reaction at 25 °C for 6 h. Filter the reaction solution, evaporate the filtrate to dryness, add a small amount of diethyl ether to dissolve, and slowly add dichloromethane while stirring until a large amount of solid precipitates. Filter and dry under vacuum at 100 °C to obtain 3.1 g of white solid, with a yield of 82.8%.

[0157] Mass spectrometry (MS / S) measurements were performed on intermediate 3 and the product lithium trifluoromethylisopropylbissulfonamide obtained in this preparation example. The MS / S mass spectrometry result for intermediate 3 was 292.94 [M], and the MS / S mass spectrometry result for the product lithium trifluoromethylisopropylbissulfonamide was 260.99 [M]. The mass decreased by 32 Da from the intermediate to the product; and 32 Da corresponds exactly to the relative mass difference between K+ and Li+, proving that step S2 of this preparation example successfully completed the metal exchange.

[0158] The intermediate 3 and the product trifluoromethylisopropylbissulfonamide lithium prepared in this preparation example were subjected to 1H NMR spectroscopy. 1 ¹H NMR (400 MHz, DMSO-d6) and fluorine NMR spectrum 19 F NMR (376 MHz, DMSO-d6) tests were performed, and the results are shown in [reference needed]. Figure 9-12 .Depend on Figure 9-12 As can be seen, the 1H NMR spectrum of intermediate 3 showed characteristic peaks at δ3.25-3.15 (m, 1H, CH) and 1.31 (d, 6H, CH3), and the fluorine NMR spectrum showed a characteristic peak at δ-77.56 (CF3), proving that the intermediate with the described structure was successfully synthesized; the 1H NMR spectrum of the product showed characteristic peaks at δ3.26-3.14 (m, 1H, CH) and 1.31 (d, 6H, CH3), and the fluorine NMR spectrum showed a characteristic peak at δ-77.60 (CF3), proving that the trifluoromethylisopropylbissulfonamide lithium with the described structure was successfully synthesized.

[0159] Experimental Example According to the formulations in Table 1, the electrolytes of Examples 1-14 and Comparative Examples 1-5 were prepared, and the electrolytes were assembled into 2Ah lithium-ion pouch batteries in an argon atmosphere, wherein the positive electrode active material was lithium manganese oxide (LMO) and the negative electrode active material was graphite.

[0160] Table 1. Composition and Amount of Electrolyte in Examples and Comparative Examples

[0161] Performance testing 1. High-temperature long-cycle test (45℃) The lithium batteries assembled in the above experimental examples were charged to 4.2V at 0.1C at 25°C and left to stand for 5 minutes; then discharged to 2.8V at 0.1C and left to stand for 5 minutes. After formation, the batteries were charged to 4.2V at 1C at 45°C and left to stand for 5 minutes; then discharged to 2.8V at 1C and left to stand for 5 minutes. This process was repeated 200 times, and the results are shown in Table 2.

[0162] Table 2. Comparison of specific capacity of different lithium batteries under long-cycle discharge at high temperature (45℃) and 1C conditions.

[0163] As shown in Table 2, the initial discharge capacity of Example 1 is higher than that of Comparative Examples 1-5, proving that the fluoroalkyl alkyl disulfonamide lithium described in this invention is beneficial to improving the conductivity and other properties of lithium batteries.

[0164] After 100 to 200 cycles of testing, the discharge capacity of Example 1 was significantly higher than that of Comparative Example 1 without Compound 1 and Comparative Example 2 without FEC, proving that the use of fluoroalkyl alkyl disulfonamide lithium and FEC in this invention is beneficial to improving the stability of lithium batteries, achieving a technical effect of 1+1>2 and having a synergistic effect.

[0165] 2. High-temperature storage test (55℃) The lithium batteries assembled in the above experimental examples were charged to 4.2V at 0.1C at 25℃ and left to stand for 5 minutes; then discharged to 2.8V at 0.1C and left to stand for 5 minutes. After formation, the batteries were charged to 4.2V at 1C. Subsequently, each lithium battery was left to stand at a high temperature of 55℃ for 7 days and then subjected to a room temperature discharge test (1C, cutoff voltage of 2.8V) to test its discharge capacity and discharge capacity recovery rate. The results are shown in Table 3.

[0166] The formula for calculating the discharge capacity recovery rate is: Discharge capacity recovery rate = (Average discharge capacity after 7 days at 55℃) / (Average initial discharge capacity) × 100% Table 3. Discharge capacity and discharge capacity recovery rate of different lithium batteries before and after high-temperature storage

[0167] As shown in Table 3, the initial discharge capacity of Examples 1-2 was slightly higher than that of Comparative Examples 1-2. However, after being placed at 55°C for 7 days, the remaining capacity and discharge capacity of Comparative Example 1 were significantly reduced, and the discharge capacity recovery rate was significantly lower than that of Example 1. This proves that the fluoroalkyl alkyl disulfonamide lithium described in this invention is beneficial to improving the stability and high-temperature performance of lithium batteries.

[0168] In the description of this specification, the references to terms such as "a preparation example," "some preparation examples," "implementation," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that preparation example or example is included in at least one preparation example or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same preparation example or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more preparation examples or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different preparation examples or examples described in this specification, as well as the features of different preparation examples or examples.

[0169] Although examples of preparation of the present invention have been shown and described above, it is understood that the above examples 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 examples within the scope of the present invention.

Claims

1. A fluoroalkylalkylbissulfonamide lithium, characterized in that, The structure shown in Equation IV satisfies the general formula: Wherein, R1 is one or more of monofluoromethyl, difluoromethyl, or trifluoromethyl; n is an integer from 0 to 9; R2 is selected from C1 to C2. 10 Alkyl groups.

2. The fluoroalkylalkylbissulfonamide lithium according to claim 1, characterized in that, At least one of the following conditions must be met: R1 is trifluoromethyl; R2 is one or more of methyl, ethyl, and isopropyl.

3. A method for preparing fluoroalkylalkylbissulfonamide lithium as described in claim 1 or 2, characterized in that, include: A mixture of fluoroalkylsulfonyl chloride, alkylsulfonamide, and a weak base is carried out in the first reaction to obtain fluoroalkylalkylbissulfonamide potassium. A second reaction was carried out by mixing fluoroalkylalkylbissulfonamide potassium and lithium tetrafluoroborate to obtain the fluoroalkylalkylbissulfonamide lithium.

4. The preparation method according to claim 3, characterized in that, At least one of the following conditions must be met: The weak base includes at least one of potassium carbonate and potassium bicarbonate; The first reaction is carried out in the presence of a first organic solvent, which includes at least one of acetonitrile and dichloromethane. The molar ratio of the fluoroalkyl sulfonyl chloride to the alkyl sulfonamide is 1:(0.9~1.2). The molar ratio of the fluoroalkyl sulfonyl chloride to the weak base is 1:(2-4). The reaction temperature of the first reaction is 10℃~30℃, and the reaction time is 12h~30h; The second reaction is carried out in the presence of a second organic solvent, which includes at least one of acetonitrile and dichloromethane. The molar ratio of the fluoroalkyl alkyl bissulfonamide potassium to lithium tetrafluoroborate is 1:(0.95~1.05). The reaction temperature of the second reaction is 10℃~30℃, and the reaction time is 4h~16h.

5. The preparation method according to claim 3, characterized in that, At least one of the following conditions must be met: The fluoroalkyl sulfonyl chloride satisfies the general structural formula shown in Formula I: ; The alkylsulfonamide satisfies the general structural formula shown in Formula II: .

6. The preparation method according to claim 5, characterized in that... Formula I includes at least one of the following structural formulas: Wherein, X is a sulfonyl chloride group -SO2Cl; Optionally, Equation I is At least one of them.

7. The preparation method according to claim 5, characterized in that, Formula II includes at least one of the following structural formulas: Wherein, Y is a sulfonamide group -SO2NH2; Optionally, Formula II is At least one of them.

8. An electrolyte, characterized in that, The electrolyte comprises the fluoroalkylalkylbissulfonamide lithium according to claim 1 or 2, and / or the fluoroalkylalkylbissulfonamide lithium prepared by the preparation method according to any one of claims 3 to 7.

9. The electrolyte according to claim 8, characterized in that, At least one of the following conditions must be met: The electrolyte further includes fluoroethylene carbonate; optionally, the mass ratio of the fluoroalkylalkylbissulfonamide lithium to fluoroethylene carbonate is 1:15 to 20:

1. The electrolyte further includes one or more of lithium salt, additives, and solvents; optionally, the lithium salt includes at least one first lithium salt and a second lithium salt; optionally, the mass percentage of the second lithium salt in the electrolyte is 0 to 3 wt%.

10. A lithium battery, characterized in that, Includes the electrolyte as described in claim 8 or 9.

Images