Preparation method and application of disulfonic acid derivative of 1, 3-dithiole-4, 5-diketone

Abstract

The invention discloses a preparation method and application of a disulfonic acid derivative of 1, 3-dithiole-4, 5-diketone, and belongs to the technical field of battery electrolyte additives, a target product is a dimer of ethylene sulfate, the molecular formula is C4H6O8S2, and the molecular formula is C4H6O8S2. The preparation method comprises the following steps: S1, synthesizing an intermediate: reacting 2-bromoethanol with sulfuryl chloride under the action of organic alkali to generate the intermediate; s2, Grignard exchange reaction: in anhydrous tetrahydrofuran, carrying out Grignard exchange reaction on the intermediate and isopropyl magnesium chloride to generate a Grignard reagent; s3, carrying out metallization conversion reaction to generate an organic zinc reagent: carrying out metallization conversion reaction on the Grignard reagent and zinc chloride to generate the organic zinc reagent; and S4, cross-coupling reaction: in the presence of a palladium catalyst and a ligand, carrying out cross-coupling reaction on the organic zinc reagent and the intermediate of another molecule to obtain a target product, the invention not only provides an ethylene sulfate dimer synthesis path, but also develops the electrolyte additive with excellent performance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery electrolyte additives, and relates to a preparation method of a disulfonic acid derivative, in particular to a disulfonic acid derivative of 1,3-dithiol-4,5-diketone and application thereof. BACKGROUND

[0002] With the transformation of global energy structure and the rapid development of new energy automobile industry, the requirements for the energy density, cycle life and safety performance of lithium ion batteries are increasingly improved. As a core component of the battery, the chemical stability of the electrolyte plays a decisive role in the performance of the battery. During the first charging process of the battery, the conventional carbonate-based electrolyte will undergo irreversible decomposition on the surface of the negative electrode, forming an unstable solid-state electrolyte interface film, i.e. SEI film, which leads to continuous consumption of active lithium, increase of battery internal resistance, rapid capacity decay, and safety hazards.

[0003] To improve the characteristics of the SEI film, adding functional electrolyte additives has become an effective solution. Among them, vinyl sulfate as a classic film-forming additive can form a dense and stable SEI film on the negative electrode, which significantly improves the cycle life of the battery. However, the molecular weight of vinyl sulfate is small, and its stability in high temperature and high pressure environment is limited, and the oxidation stability at the high voltage positive electrode end is not improved enough, which is difficult to meet the performance requirements of the next generation of batteries.

[0004] Therefore, developing vinyl sulfate analogues with larger molecular weight and more stable structure has become an important research direction. The target product of the present application is a new type of vinyl sulfate additive. Its structure is shown as formula 1, and its molecule can have multiple film-forming functional groups, which can theoretically improve the high temperature, high pressure and cycle performance of the battery.

[0005] However, the synthesis of this molecule faces great challenges. The most direct synthesis idea is to develop a dimerization strategy to directly connect two vinyl sulfate monomers through a carbon-carbon bond, but this synthesis route is not currently disclosed. The fundamental difficulty lies in the fact that the vinyl sulfate molecule itself lacks effective reaction sites to achieve selective coupling. If it is activated by halogenation, the resulting bifunctional intermediate (such as dihalide) has very high reactivity, and when trying to couple itself or react with another molecule, it is difficult to avoid the occurrence of polymerization and crosslinking side reactions, which in turn leads to the product becoming a complex mixture that cannot be separated and purified. In addition, the cyclic sulfate skeleton is easily ring-opening and decomposed in the presence of strong acid, strong base or strong nucleophile / electrophile, making most traditional coupling conditions unsuitable.

[0006] Therefore, how to realize precise, efficient and specific C-C bond coupling between two highly sensitive molecules has become the core bottleneck restricting the development of synthesis and development technology of such high-performance additives. SUMMARY

[0007] The purpose of this invention is to overcome the shortcomings of the existing vinyl sulfate dimerization route, such as poor selectivity, numerous side reactions, and difficulty in scaling up, and to provide a mild, highly selective, and scalable synthetic route for the disulfonic acid derivative of 1,3-dithiocyclopentene-4,5-dione, thereby laying the foundation for the application of this compound as a high-performance lithium-ion battery electrolyte additive.

[0008] The technical solution adopted in this invention provides a method for preparing disulfonic acid derivatives of 1,3-dithiacyclopentene-4,5-dione. The key point is that the disulfonic acid derivatives of 1,3-dithiacyclopentene-4,5-dione are dimers of vinyl sulfate having the structure shown in Formula 1, with the molecular formula C4H6O8S2.

[0010]

[0011] The above preparation method specifically includes:

[0012] Synthesis of S1 intermediate: 2-bromoethanol is reacted with sulfuryl chloride in the presence of an organic base to generate an intermediate, namely 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide.

[0013] S2 Grignard exchange reaction: In anhydrous tetrahydrofuran, the intermediate undergoes a Grignard exchange reaction with isopropyl magnesium chloride to generate a Grignard reagent;

[0014] S3 Transmetallization Reaction to Generate Organozinc Reagent: The above Grignard reagent undergoes a transmetallization reaction with zinc chloride to generate an organozinc reagent;

[0015] S4 cross-coupling reaction: In the presence of a palladium catalyst and ligand, the above organozinc reagent is cross-coupled with another intermediate molecule to obtain the compound shown in Formula 1.

[0016] Specifically, in step S1, the organic base is triethylamine or pyridine; the molar ratio of 2-bromoethanol, thioyl chloride, and the organic base is 1:(1-1.2):(2.0-2.5); the structural formula of the above-mentioned 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide is shown in Formula 2.

[0017]

[0018] Furthermore, the reaction temperature of step S1 is -10℃ to 5℃, the reaction time is 1h to 4h, and the reaction solvent is anhydrous dichloromethane. After the reaction is completed, the reaction solution is poured into ice water, extracted with dichloromethane, and the organic phases are combined. After washing, drying, filtration, vacuum concentration, and column purification, the above intermediate is obtained.

[0019] Specifically, in step S2, the molar ratio of the above intermediate to isopropyl magnesium chloride is 1:1 to 1.2; the above isopropyl magnesium chloride is an isopropyl magnesium chloride lithium salt complex; the reaction temperature of the above Grignard exchange reaction is -80℃ to -75℃, and the reaction time is 1h to 2h.

[0020] Preferably, the amount of zinc chloride added in step S3 is 1.1 to 1.3 times the molar amount of the intermediate used in step S2, the reaction temperature is -2℃ to 2℃, and the reaction time is 1.5h to 2.5h.

[0021] Furthermore, in step S4, the palladium catalyst is tris(dibenzylideneacetone)dipalladium, and the ligand is 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl; the molar ratio of the palladium catalyst, ligand, and intermediate added in step S4 to that added in step S2 is (0.8–1.2):(1.5–2.5):100.

[0022] Preferably, the cross-coupling reaction temperature in step S4 is 40℃~60℃ and the reaction time is 10h~14h.

[0023] Furthermore, after the cross-coupling reaction in step S4 is completed, the reaction is quenched with saturated NH4Cl solution, the product is extracted with ethyl acetate, the organic phases are combined, and the resulting organic phase is purified by washing, drying and vacuum concentration.

[0024] Preferably, the above purification process specifically involves purifying the obtained product by column chromatography, wherein the eluent for column chromatography is a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of (3-1):1.

[0025] The key to the application of the above-mentioned 1,3-dithiocyclopentene-4,5-dione disulfonic acid derivative as an additive in lithium-ion battery electrolytes is that the amount added is 0.2% to 0.8% of the electrolyte mass.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] First, this invention overcomes the technical bottleneck in the synthesis of vinyl sulfate dimers. Through an innovative Grignard exchange-transmetallization-cross-coupling reaction pathway, it achieves for the first time the efficient and highly selective synthesis of disulfonic acid derivatives of 1,3-dithiacyclopentene-4,5-dione. The preparation method of this invention cleverly converts one intermediate molecule into a stable organozinc reagent, which is then cross-coupled with another intermediate molecule, effectively avoiding the technical difficulties of poor selectivity, numerous side reactions, and complex products inherent in direct dimerization strategies. The preparation method of this invention achieves a product yield of over 65% and a purity exceeding 99%, far superior to the results obtained by omitting the transmetallization step or changing the Grignard reagent in the comparative examples.

[0028] Secondly, the target product prepared by this invention, as an additive for lithium-ion battery electrolytes, exhibits significantly superior high-voltage and high-temperature performance compared to the traditional additive ethylene sulfate. Application examples show that after 500 cycles at 4.6V high voltage and 60℃ high temperature, the battery with the product of this invention still retains over 80% of its capacity, significantly better than the control group. This confirms that its larger molecular weight and more stable molecular structure can form a denser electrode interface film, effectively inhibiting the decomposition of the electrolyte under harsh conditions, perfectly solving the technical defect of insufficient stability of ethylene sulfate under high voltage and high temperature environments.

[0029] Third, while improving battery cycle performance, the product of this invention fully possesses the excellent safety performance of the vinyl sulfate group. Battery safety test results show that the experimental group with the sample of this invention can maintain normal operation under extreme conditions such as overcharging, short circuit, and thermal abuse, without catching fire or exploding. Its safety performance is comparable to that of the vinyl sulfate additive and far superior to the blank control group, fully meeting the stringent requirements of new energy vehicles for high safety of battery materials.

[0030] In summary, this invention not only provides a novel and efficient synthetic route for vinyl sulfate dimers, but also develops a new electrolyte additive with excellent overall performance, providing an effective material solution for developing next-generation lithium-ion batteries with high energy density, long lifespan, and high safety. Attached Figure Description

[0031] Figure 1 This is the NMR spectrum of sample 1 of the present invention.

[0032] Figure 2 This is the high-performance gas chromatography-mass spectrometry (HPLC-MS) spectrum of sample 1 of this invention.

[0033] Figure 3 This is the high-performance gas chromatogram of sample 1 of the present invention. Detailed Implementation

[0034] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0035] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0036] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0037] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0038] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0039] Unless otherwise specified in the examples, the procedures can be followed according to conventional conditions; unless the manufacturers of the reagents or instruments used are specified, they are all conventional products that can be purchased commercially.

[0040] Example 1

[0041] This embodiment prepares a disulfonic acid derivative of 1,3-dithiocyclopentene-4,5-dione with the structure shown in Formula 1. The specific process is as follows:

[0042] Synthesis of S1 intermediate:

[0043] Add 0.3 mol of 2-bromoethanol and 450 mL of anhydrous dichloromethane sequentially to the reactor; under stirring conditions of 0 °C and 500 r / min, slowly add 100 mL of anhydrous dichloromethane solution containing 0.69 mol of triethylamine dropwise.

[0044] After the addition is complete, continue to maintain the low temperature and stirring conditions, and add 100 mL of anhydrous dichloromethane solution containing 0.33 mol of thioyl chloride.

[0045] After the addition is complete, the reaction is carried out for 3 hours under the condition of controlling the reaction temperature at 0℃ and continuous stirring.

[0046] After the reaction was completed, the reaction solution was poured into ice water for separation. The aqueous phase was extracted with dichloromethane and all organic phases were combined. The organic phases were washed successively with saturated sodium bicarbonate solution, water and saturated saline solution.

[0047] The organic phase was dried with anhydrous magnesium sulfate, filtered, and then concentrated under reduced pressure using a rotary evaporator to obtain the crude intermediate.

[0048] The crude intermediate obtained by chromatographic column purification was carried out using a mixture of petroleum ether and ethyl acetate in a volume ratio of 4:1 to obtain an intermediate with the structure shown in Formula 2, namely 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide, which is referred to as intermediate sample 1.

[0049] In this step, the molar ratio of 2-bromoethanol, thioyl chloride, and triethylamine is 1:1.1:2.3.

[0050] S2 Grignard exchange reaction:

[0051] Under nitrogen gas protection, 0.1 mol of intermediate sample 1 and 60 mL of anhydrous tetrahydrofuran were added to a dry Schlenk reaction tube.

[0052] The reaction system was cooled to -78°C, and 85 mL of tetrahydrofuran solution containing 0.11 mol of isopropyl magnesium chloride-lithium chloride was slowly added dropwise through a syringe at a speed of 400 r / min. The Grignard exchange reaction was carried out for 1.5 h while maintaining the low temperature and stirring to generate Grignard reagents.

[0053] S3 transmetallization reaction generates organozinc reagent:

[0054] While maintaining the low temperature and stirring conditions of the reaction system in step S2, add 0.12 mol of zinc chloride at once;

[0055] The reaction system was heated and the reaction temperature was controlled at 0℃. The metallization reaction was carried out at a rotation speed of 400 r / min for 2 h to generate an organozinc reagent.

[0056] S4 cross-coupling reaction:

[0057] To the reaction system of step S3, 1.0 mmol of palladium catalyst tris(dibenzylacetone)dipalladium, 2.0 mmol of ligand 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl and 0.1 mol of intermediate sample 1 were added sequentially.

[0058] The reaction system was heated and the reaction temperature was controlled at 50℃. The rotation speed was increased to 800 r / min, so that the organozinc reagent prepared in step S3 was cross-coupled with another molecule of 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide for 12 h to obtain the compound shown in Formula 1.

[0059] After the reaction is complete, the reaction solution is cooled to room temperature and the reaction is quenched with saturated NH4Cl solution.

[0060] The product was extracted with ethyl acetate, and the organic phases were combined. The resulting organic phases were washed with water and saturated brine, dried with anhydrous magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure by rotary evaporator and purified to obtain the target product with the structural formula shown in Formula 1, which is denoted as Sample 1.

[0061] The purification process involves purifying the obtained product using column chromatography, with the eluent being a mixture of petroleum ether and ethyl acetate in a volume ratio of 2:1.

[0062] In this step, the molar ratio of the palladium catalyst, ligand, and intermediate added in step S2 is 1.0:2.0:100.

[0063] Example 2

[0064] This embodiment prepares a disulfonic acid derivative of 1,3-dithiocyclopentene-4,5-dione with the structure shown in Formula 1. The specific process is as follows:

[0065] Synthesis of S1 intermediate:

[0066] Add 0.3 mol of 2-bromoethanol and 500 mL of anhydrous dichloromethane sequentially to the reactor; under stirring conditions of 0 °C and 550 r / min, slowly add 120 mL of anhydrous dichloromethane solution containing 0.75 mol of pyridine.

[0067] After the addition is complete, continue to maintain the low temperature and stirring conditions, and add 80 mL of anhydrous dichloromethane solution containing 0.3 mol of thioyl chloride.

[0068] After the addition is complete, the reaction is carried out for 4 hours under the condition of controlling the reaction temperature at -10℃ and continuous stirring.

[0069] After the reaction was completed, the reaction solution was poured into ice water for separation. The aqueous phase was extracted with dichloromethane and all organic phases were combined. The organic phases were washed successively with saturated sodium bicarbonate solution, water and saturated saline solution.

[0070] The organic phase was dried with anhydrous magnesium sulfate, filtered, and then concentrated under reduced pressure using a rotary evaporator to obtain the crude intermediate.

[0071] The crude intermediate obtained by chromatographic column purification was carried out with a mixture of petroleum ether and ethyl acetate in a volume ratio of 3:1 to obtain an intermediate with the structure shown in Formula 2, namely 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide, which is referred to as intermediate sample 2.

[0072] In this step, the molar ratio of 2-bromoethanol, thioyl chloride, and the organic base pyridine is 1:1:2.5.

[0073] S2 Grignard exchange reaction:

[0074] Under nitrogen gas protection, 0.1 mol of intermediate sample 2 and 60 mL of anhydrous tetrahydrofuran were added to a dry Schlenk reaction tube.

[0075] The reaction system was cooled to -75°C, and 90 mL of tetrahydrofuran solution containing 0.12 mol of isopropyl magnesium chloride-lithium chloride was slowly added dropwise through a syringe at a speed of 350 r / min. The Grignard exchange reaction was carried out for 1 h while maintaining the low temperature and stirring to generate Grignard reagents.

[0076] S3 transmetallization reaction generates organozinc reagent:

[0077] While maintaining the low temperature and stirring conditions of the reaction system in step S2, add 0.11 mol of zinc chloride at once;

[0078] The reaction system was heated to 2°C and the metallization reaction was carried out at 350 r / min for 1.5 h to generate an organozinc reagent.

[0079] S4 cross-coupling reaction:

[0080] To the reaction system of step S3, 0.8 mmol of palladium catalyst tris(dibenzylacetone)dipalladium, 2.5 mmol of ligand 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl and 0.1 mol of intermediate sample 2 were added sequentially.

[0081] The reaction system was heated and the reaction temperature was controlled at 40℃. The rotation speed was increased to 850 r / min, so that the organozinc reagent prepared in step S3 was cross-coupled with another molecule of 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide for 14 h to obtain the compound shown in Formula 1.

[0082] After the reaction is complete, the reaction solution is cooled to room temperature and the reaction is quenched with saturated NH4Cl solution.

[0083] The product was extracted with ethyl acetate, and the organic phases were combined. The resulting organic phases were washed with water and saturated brine, dried with anhydrous magnesium sulfate, and filtered. The filtrate was concentrated under reduced pressure by rotary evaporator and purified to obtain the target product with the structural formula shown in Formula 1, which is denoted as Sample 2.

[0084] The purification process involves purifying the obtained product using column chromatography, with the eluent being a mixture of petroleum ether and ethyl acetate in a 1:1 volume ratio.

[0085] In this step, the molar ratio of the palladium catalyst, ligand, and intermediate added in step S2 is 0.8:2.5:100.

[0086] Example 3

[0087] This embodiment prepares a disulfonic acid derivative of 1,3-dithiocyclopentene-4,5-dione with the structure shown in Formula 1. The specific process is as follows:

[0088] Synthesis of S1 intermediate:

[0089] Add 0.3 mol of 2-bromoethanol and 400 mL of anhydrous dichloromethane sequentially to the reactor; under stirring conditions of 0 °C and 450 r / min, slowly add 90 mL of anhydrous dichloromethane solution containing 0.6 mol of triethylamine dropwise.

[0090] After the addition is complete, continue to maintain the low temperature and stirring conditions, and add 100 mL of anhydrous dichloromethane solution containing 0.36 mol of thioyl chloride.

[0091] After the addition is complete, the reaction is carried out for 1 hour under the condition of controlling the reaction temperature at 5℃ and continuous stirring.

[0092] After the reaction was completed, the reaction solution was poured into ice water for separation. The aqueous phase was extracted with dichloromethane and all organic phases were combined. The organic phases were washed successively with saturated sodium bicarbonate solution, water and saturated saline solution.

[0093] The organic phase was dried with anhydrous magnesium sulfate, filtered, and then concentrated under reduced pressure using a rotary evaporator to obtain the crude intermediate.

[0094] The crude intermediate obtained by chromatographic column purification was carried out using a mixture of petroleum ether and ethyl acetate in a volume ratio of 5:1 to obtain an intermediate with the structure shown in Formula 2, namely 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide, which is referred to as intermediate sample 3.

[0095] In this step, the molar ratio of 2-bromoethanol, thioyl chloride, and triethylamine is 1:1.2:2.0.

[0096] S2 Grignard exchange reaction:

[0097] Under nitrogen gas protection, 0.1 mol of intermediate sample 3 and 60 mL of anhydrous tetrahydrofuran were added to a dry Schlenk reaction tube.

[0098] The reaction system was cooled to -80°C, and 80 mL of tetrahydrofuran solution containing 0.1 mol of isopropyl magnesium chloride-lithium chloride was slowly added dropwise through a syringe at a speed of 450 r / min. The Grignard exchange reaction was carried out for 2 h while maintaining the low temperature and stirring to generate Grignard reagents.

[0099] S3 transmetallation reaction generates organozinc reagent:

[0100] While maintaining the low temperature and stirring conditions of the reaction system in step S2, add 0.13 mol of zinc chloride at once;

[0101] The reaction system was heated and the reaction temperature was controlled at -2℃. The metallization reaction was carried out at a rotation speed of 450 r / min for 2.5 h to generate an organozinc reagent.

[0102] S4 cross-coupling reaction:

[0103] To the reaction system of step S3, 1.2 mmol of palladium catalyst tris(dibenzylacetone)dipalladium, 1.5 mmol of ligand 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl and 0.1 mol of intermediate sample 3 were added sequentially.

[0104] The reaction system was heated and the reaction temperature was controlled at 60℃. The rotation speed was increased to 750 r / min, so that the organozinc reagent prepared in step S3 was cross-coupled with another molecule of 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide for 10 h to obtain the compound shown in Formula 1.

[0105] After the reaction is complete, the reaction solution is cooled to room temperature and the reaction is quenched with saturated NH4Cl solution.

[0106] The product was extracted with ethyl acetate, and the organic phases were combined. The resulting organic phases were washed with water and saturated brine, dried with anhydrous magnesium sulfate, and filtered. The filtrate was concentrated under reduced pressure by rotary evaporator and purified to obtain the target product with the structural formula shown in Formula 1, which is denoted as Sample 3.

[0107] The purification process involves purifying the obtained product using column chromatography, with the eluent being a mixture of petroleum ether and ethyl acetate in a volume ratio of 3:1.

[0108] In this step, the molar ratio of the palladium catalyst, ligand, and intermediate added in step S2 is 1.2:1.5:100.

[0109] Comparative Example 1

[0110] The implementation method of this comparative example is the same as that of Example 1, except that in step S2, isopropyl magnesium chloride-lithium chloride is not used, but an equimolar amount of cyclopropyl magnesium chloride-lithium chloride is used. After the cyclopropyl magnesium chloride-lithium chloride solution is added dropwise, it is found that the color of the reaction system rapidly darkens and a large amount of flocculent precipitate is produced. The subsequent steps are the same as those of Example 1, but the target product cannot be separated and purified.

[0111] Comparative Example 2

[0112] The implementation method of this comparative example omits the S3 metallization reaction to generate organozinc reagent in Example 1. The specific preparation method is as follows:

[0113] Synthesis of intermediate S1: Same as step S1 in Example 1.

[0114] S2 Grignard exchange reaction: Same as step S2 in Example 1.

[0115] S3 cross-coupling reaction:

[0116] To the reaction system of step S2, i.e. the Grignard reagent system, 1.0 mmol of palladium catalyst tris(dibenzylacetone)dipalladium, 2.0 mmol of ligand 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl and 0.1 mol of intermediate sample 1 were added sequentially; the subsequent process was the same as step S4 of Example 1, and the resulting product was designated as reference standard 1.

[0117] Comparative Example 3

[0118] This comparative example uses a direct coupling method, specifically as follows:

[0119] Synthesis of intermediate S1: Same as step S1 in Example 1.

[0120] S2 direct coupling reaction:

[0121] Under nitrogen protection, 0.2 mol of intermediate sample 1, 2.0 mmol of palladium catalyst tris(dibenzylacetone)dipalladium, 4.0 mmol of ligand 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl and 120 mL of anhydrous tetrahydrofuran were added to a dry Schlenk reaction tube.

[0122] The reaction system was heated to 50°C and stirred at 800 r / min for 12 h.

[0123] After the reaction was completed, the reaction solution was cooled to room temperature, quenched with saturated NH4Cl solution, extracted with ethyl acetate, the organic phases were combined and dried over anhydrous magnesium sulfate and filtered. The filtrate was concentrated under reduced pressure using a rotary evaporator to obtain a black tar-like solid that could not be separated into the target product by column chromatography.

[0124] Analysis and Testing

[0125] Samples 1-3 prepared in this invention were analyzed by 1H NMR and high-performance gas chromatography-mass spectrometry (GC-MS), confirming that their structures conform to the structural characteristics of the disulfonic acid derivative of 1,3-dithiacyclopentene-4,5-dione shown in Formula 1. The analytical chromatogram for sample 1 is shown in [reference needed]. Figure 1 and 2 .

[0126] This invention also utilizes a high-performance gas chromatograph to test the purity of samples 1-3 and reference standard 1, and calculates the yield using the following formula. The results are shown in Table 1 and... Figure 3 Among them, the chromatographic peaks with elution times between 9 min and 9.2 min are the target products of this invention.

[0127] Intermediate yield = actual weight of intermediate obtained (g) / theoretical yield calculated based on the amount of 2-bromoethanol used (g) × 100%, rounded to the nearest integer.

[0128] Product yield = Actual weight of the product obtained (g) / Theoretical yield calculated based on the total amount of intermediates (g) × 100%, and the result is rounded to one decimal place.

[0129] Table 1: Summary of Product Purity and Yield Results

[0130]

[0131]

[0132] As can be seen from the results in Table 1, the product yield of the sample prepared by this invention is higher than 65% and the product purity is higher than 99.0%, which meets the requirements for use as an electrolyte additive.

[0133] In Comparative Example 2, omitting the transmetalation step resulted in an extremely low product yield, and the main product was a self-coupling byproduct, leading to very low purity. This highlights the crucial role of the transmetalation step in the preparation method of this invention. This step transforms the highly reactive, low-selectivity Grignard reagent into a chemically mild, highly selective organozinc reagent, thereby efficiently suppressing the self-coupling side reaction and achieving highly selective cross-coupling. This step is indispensable; omitting it will prevent obtaining the target cross-coupling product in an acceptable yield.

[0134] Furthermore, neither Comparative Examples 1 nor 3 yielded the target product.

[0135] In Comparative Example 1, cyclopropyl magnesium chloride-lithium chloride was used. This substance is much more basic than isopropyl magnesium chloride, preferentially deprotonating the more acidic methylene proton on the sulfate ester ring or directly attacking the sulfur atom, leading to ring-opening, decomposition, and polymerization of the sulfate ester ring. Therefore, the desired Grignard reagent cannot be generated. It is evident that the basicity of the Grignard reagent is crucial to the success of the reaction in this invention. An excessively basic cyclopropyl derivative will cause the sensitive sulfate ester intermediate to undergo ring-opening decomposition, preventing subsequent reactions and ultimately failing to yield the target product.

[0136] In Comparative Example 3, a direct coupling strategy was employed, confirming that the two activated vinyl sulfate monomers cannot undergo an effective coupling reaction directly. Instead, they tend towards uncontrollable polymerization and decomposition. Under palladium catalysis and heating conditions, these two highly reactive bromides undergo violent polymerization, cross-linking, and decomposition side reactions, making it completely impossible to directionally generate a single dimer target product.

[0137] Application Examples

[0138] Electrolytes containing 0.2%, 0.5%, and 0.8% by mass of Sample 1 were added to lithium battery electrolytes as application samples 1, 2, and 3, respectively. Electrolytes without any additives were used as a blank control, and electrolytes containing 0.5% by mass of vinyl sulfate were used as application controls. Simultaneously, lithium batteries with a capacity of 1000mAh were fabricated using these electrolytes for battery application testing, with ternary lithium as the positive electrode material and graphite as the negative electrode.

[0139] (I) Battery Electrical Safety Testing

[0140] 1. External short circuit at room temperature

[0141] After fully charging the battery, place it in an environment of 20℃±5℃. After the battery surface temperature reaches 20℃±5℃, leave it for another 30 minutes. Then connect the positive and negative terminals of the battery with wires, and ensure that all external resistances are 80mΩ±20mΩ. Monitor the battery temperature change during the experiment. The battery should not catch fire or explode, and the maximum temperature should not exceed 150℃.

[0142] 2. High-temperature external short circuit

[0143] After fully charging the battery, place it in an environment of 55℃±5℃. After the battery surface temperature reaches 55℃±5℃, leave it for another 30 minutes. Then connect the positive and negative terminals of the battery with wires, and ensure that all external resistances are 80mΩ±20mΩ. Monitor the battery temperature change during the experiment. The battery should not catch fire or explode, and the maximum temperature should not exceed 150℃.

[0144] 3. Overcharging

[0145] After the battery is fully discharged, it is first charged with a constant current of 3CA to a test voltage of 4.6V. Then, it is charged with a constant voltage of the test voltage. The battery should not catch fire or explode.

[0146] 4. Forced discharge

[0147] After the battery is fully discharged, it should be reverse-charged at a current of 1CA for 90 minutes. The battery should not catch fire or explode.

[0148] The test results for battery electrical safety are shown in Table 2:

[0149] Table 2: Test Results of Battery Electrical Safety

[0150] Sample Normal temperature external short circuit High temperature external short circuit Overcharge Forced discharge Application sample 1 Normal Normal Normal Normal Application sample 2 Normal Normal Normal Normal Application sample 3 Normal Normal Normal Normal Application comparison Normal Normal Normal Normal Blank comparison Fire Temperature over 150°C Fire ——

[0151] As can be seen from the results in Table 2, the samples prepared in this invention or the experimental group of applications with added vinyl sulfate to the lithium battery electrolyte all performed normally in the external short circuit and overcharge tests, indicating that the vinyl sulfate group can effectively enhance the electrical safety performance of lithium batteries.

[0152] (II) Battery Environmental Safety Testing

[0153] 1. Low air pressure

[0154] After fully charging the battery, place it in a vacuum chamber at 20°C, evacuate the chamber to reduce the pressure to 11.6 kPa, and maintain this pressure for 6 hours. The battery should not catch fire, explode, or leak.

[0155] 2. Temperature Cycling

[0156] After fully charging the battery, place it in a temperature-controlled chamber at 20℃±5℃ and perform the following steps:

[0157] a) Place the sample in an experimental chamber at a temperature of 75℃±2℃ for 6 hours;

[0158] b) Then the temperature of the experimental chamber is lowered to -40℃±2℃ and maintained for 6 hours, with a temperature transition time of no more than 30 minutes;

[0159] c) Raise the temperature of the experimental chamber to 75℃±2℃ again, with a temperature transition time not exceeding 30 minutes.

[0160] d) Repeat steps a) to c) for a total of 10 cycles;

[0161] The battery should not catch fire, explode, or leak.

[0162] 3. Acceleration impact

[0163] After fully charging the battery, it was fixed on the impact platform and subjected to a half-sine pulse impact test. The minimum average acceleration was 75g in the first 3ms. n Peak acceleration is 150g n ±25g n The pulse duration is 6ms ± 1ms. The battery is subjected to three acceleration impacts in each direction. The battery should not catch fire, explode, or leak.

[0164] 4. Fall

[0165] After fully charging the battery, drop it freely from a height of 1 meter onto a concrete slab. Perform four drop tests in total. The battery should not catch fire or explode.

[0166] 5. Extrusion

[0167] After fully charging the battery, place it in two planes and press it perpendicular to the plates. Apply a pressing force of 13.0kN±0.78kN between the two plates. Stop the pressing experiment once the pressure reaches the maximum value. The battery must not be short-circuited during the experiment.

[0168] 6. Heat abuse

[0169] After fully charging the battery, place it in the test chamber. The test chamber is heated at a rate of (5±2)℃ / min. When the temperature inside the chamber reaches 130℃±2℃, it is kept constant for 30 minutes. The battery should not catch fire or explode.

[0170] 7. Combustion Injection

[0171] After fully charging the battery, place it on the wire mesh of the experimental fixture. If the battery slips during the experiment, a single metal wire can be used to fix the battery sample to the wire mesh. If this does not happen, the battery should not be tied up. Heat the battery with a flame. Stop heating when any of the following three situations occur: a) the battery explodes; b) the battery burns completely; c) heating continues for 30 minutes, but the battery does not catch fire or explode. After the experiment, the components of the battery (except for the dust-like product) or the battery as a whole must not penetrate the aluminum mesh.

[0172] The test results for battery environmental safety are shown in Table 3:

[0173] Table 3: Test Results of Battery Environmental Safety Test

[0174] Sample Low air pressure Temperature cycle Acceleration impact Drop Crushing Thermal abuse Combustion injection Application sample 1 Normal Normal Normal Normal Normal No change Normal Application sample 2 Normal Normal Normal Normal Normal No change Normal Application sample 3 Normal Normal Normal Normal Normal No change Normal Application comparison Normal Normal Normal Normal Normal No change Normal Blank comparison Normal Liquid leakage Liquid leakage Normal Short circuit Explosion Explosion

[0175] As can be seen from the results in Table 3, adding the sample prepared in this invention or the experimental group containing ethylene sulfate to the lithium battery electrolyte can effectively enhance the environmental safety performance of the lithium battery.

[0176] (III) High-voltage and high-temperature electrical cycling performance test

[0177] High-voltage electric cycle performance test: The test environment temperature is 25℃±2℃. The battery is charged to 4.6V with a constant current of 1C, then charged to 0.05C with a constant voltage of 4.6V, and then discharged to 3.0V with a constant current of 1C. This is the first cycle.

[0178] High-temperature electric cycle performance test: The test environment temperature is 60℃±2℃. The battery is charged to 4.2V with a constant current of 1C, then charged to 0.05C with a constant voltage of 4.2V, and then discharged to 3.0V with a constant current of 1C. This is the first cycle.

[0179] The battery was charged / discharged for 100, 300, and 500 cycles under the conditions described above. The capacity retention rate after 100, 300, and 500 cycles was calculated, and the results are shown in Table 4.

[0180] Table 4: Summary of Battery Performance Test Results

[0181]

[0182]

[0183] As shown in Table 4, the 1,3-dithiocyclopentene-4,5-dione disulfonic acid derivative prepared in this invention, as an electrolyte additive, exhibits significant and comprehensive advantages in high-pressure and high-temperature cycling performance compared to the traditional additive vinyl sulfate and the blank control group.

[0184] Specifically, all experimental groups that added the sample of this invention exhibited significantly better cycle performance than the blank control group, demonstrating the necessity of the additive for improving battery cycle life. More importantly, under the same test conditions, the performance of the sample of this invention was significantly superior to the control group, especially after 500 cycles, where its advantages became even more pronounced. This indicates that the sample of this invention, as an additive, can form a denser and more stable electrode interface film, thereby more effectively suppressing the continuous decomposition of the electrolyte and the consumption of active materials during cycling, exhibiting excellent long-term cycle stability. This is because the sample of this invention has a larger molecular weight and a more stable molecular structure, giving it stronger antioxidant decomposition capabilities under high voltage conditions, thus better protecting the cathode material, slowing capacity decay, and solving the technical problem of insufficient stability of vinyl sulfate under high voltage. Simultaneously, the structural characteristics of the sample of this invention also enable it to maintain the stability of the interface film at high temperatures, effectively suppressing side reactions at high temperatures, significantly improving the high-temperature cycle life of the battery, and overcoming the technical defect of poor high-temperature performance of vinyl sulfate additives.

[0185] In summary, the disulfonic acid derivative provided by this invention successfully overcomes the limitations of traditional vinyl sulfate in high-pressure and high-temperature applications. It is a novel lithium-ion battery electrolyte additive with superior overall performance and has promising application prospects.

[0186] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

A method for preparing a disulfonic acid derivative of 1,1,3-dithiacyclopentene-4,5-dione, characterized in that, The disulfonic acid derivatives of 1,3-dithiacyclopentene-4,5-dione are dimers of vinyl sulfate having the structure shown in Formula 1, with the molecular formula C4H6O8S2. The preparation method specifically includes: Synthesis of S1 intermediate: 2-bromoethanol is reacted with sulfuryl chloride in the presence of an organic base to generate an intermediate, namely 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide; S2 Grignard exchange reaction: In anhydrous tetrahydrofuran, the intermediate undergoes a Grignard exchange reaction with isopropyl magnesium chloride to generate a Grignard reagent; S3 Transmetallization Reaction to Generate Organozinc Reagent: The Grignard reagent undergoes a transmetallization reaction with zinc chloride to generate an organozinc reagent; S4 cross-coupling reaction: In the presence of a palladium catalyst and ligand, the organozinc reagent is cross-coupled with another intermediate molecule to obtain the compound shown in Formula 1.

2. The preparation method according to claim 1, characterized in that, The organic base mentioned in step S1 is triethylamine or pyridine; the molar ratio of 2-bromoethanol, thioyl chloride, and the organic base is 1:(1-1.2):(2.0-2.5); the structural formula of the 3-bromo-1,3,2-dioxothiacyclopentane-2,2-dioxide is shown in Formula 2.

3. The preparation method according to claim 1, characterized in that, The reaction temperature of step S1 is -10℃ to 5℃, the reaction time is 1h to 4h, and the reaction solvent is anhydrous dichloromethane. After the reaction is completed, the reaction solution is poured into ice water, extracted with dichloromethane, and the organic phases are combined. After washing, drying and filtering, vacuum concentration and column purification, the intermediate is obtained.

4. The preparation method according to claim 1, characterized in that, The molar ratio of the intermediate and isopropyl magnesium chloride in step S2 is 1:1 to 1.2; the isopropyl magnesium chloride is an isopropyl magnesium chloride lithium salt complex; the Grignard exchange reaction is carried out at a temperature of -80℃ to -75℃ for 1 to 2 hours.

5. The preparation method according to claim 1, characterized in that, The amount of zinc chloride added in step S3 is 1.1 to 1.3 times the molar amount of the intermediate used in step S2, the reaction temperature is -2℃ to 2℃, and the reaction time is 1.5h to 2.5h.

6. The preparation method according to claim 1, characterized in that, The palladium catalyst in step S4 is tris(dibenzylacetone)dipalladium, and the ligand is 2-dicyclohexylphosphine-2',6'-dimethoxybiphenyl; the molar ratio of the palladium catalyst, ligand and intermediate added in step S4 to that added in step S2 is (0.8-1.2):(1.5-2.5):

00.

7. The preparation method according to claim 1, characterized in that, The cross-coupling reaction temperature in step S4 is 40℃~60℃, and the reaction time is 10h~14h.

8. The preparation method according to claim 1, characterized in that, After the cross-coupling reaction in step S4 is completed, the reaction is quenched with saturated NH4Cl solution, the product is extracted with ethyl acetate, the organic phases are combined, and the resulting organic phase is purified after washing, drying and vacuum concentration.

9. The preparation method according to claim 8, characterized in that, The purification process is as follows: the obtained product is purified by column chromatography, and the eluent for column chromatography is a mixed solvent of petroleum ether and ethyl acetate in a volume ratio of (3-1):

1.

10. The application of a disulfonic acid derivative of 1,3-dithiacyclopentene-4,5-dione as described in claim 1 as an additive in a lithium-ion battery electrolyte, characterized in that, The amount added is 0.2% to 0.8% of the electrolyte mass.

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