Chalcogenide bicyclic compound as well as preparation method and application thereof

Abstract

The invention discloses a chalcogenide bicyclic compound as well as a preparation method and application thereof. The chalcogenide bicyclic compound has the following structural formula, x and Y are respectively and independently selected from any one of P, B and P = O; a and B are respectively and independently selected from any one of O, a carbonyl group, a sulfinyl group, a sulfuryl group, a substituted or unsubstituted C1-C6 alkylene group, a substituted or unsubstituted C2-C10 alkenyl group, a substituted or unsubstituted C2-C10 alkynyl group, a substituted or unsubstituted C2-C10 cyano group and an aryl group; the compound has a unique and novel annular structure, adds a new member for the variety of chalcogenide compounds, is suitable for being used as an additive or a catalyst of a lithium ion battery electrolyte or participating in drug molecule design, and has important theoretical significance and practical application value; and the reaction conditions adopted in the preparation process are mild, and the product purity and yield are high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of chemical synthesis, and particularly relates to a sulfur-containing bicyclic compound and a preparation method and application thereof. BACKGROUND

[0002] In the field of organic chemistry, cyclic compounds have always been the focus of research due to their unique structure and properties. Sulfur-containing compounds have shown great application potential in material science, medicinal chemistry, catalytic chemistry and other fields due to their special electronic structure of sulfur atoms, rich chemical activity and diverse coordination ability. However, the existing sulfur-containing compounds have many shortcomings.

[0003] Most of the existing sulfur-containing compounds are monocyclic structures, and the types of structures are limited, which is difficult to meet the needs of diversification of functions in different application scenarios. In addition, in the preparation of sulfur-containing compounds, the existing synthesis and preparation methods often have problems such as complicated reaction steps, harsh reaction conditions, and low yield, which limit their large-scale production and application.

[0004] Therefore, it is of great significance to develop a sulfur-containing bicyclic compound with novel structure, excellent performance and easy preparation for promoting the development of related fields. SUMMARY

[0005] Therefore, the purpose of the present application is to provide a sulfur-containing bicyclic compound and a preparation method and application thereof, which has a unique and novel cyclic structure, adds a new member to the category of sulfur-containing compounds, is suitable for being used as an additive or catalyst for lithium ion battery electrolyte or participating in drug molecule design, and has important theoretical significance and practical application value. The reaction conditions used in the preparation process are mild, and the product purity and yield are high.

[0006] The technical solutions adopted by the present application are as follows: A sulfur-containing bicyclic compound, which has the following structural formula: ; X and Y are independently selected from any one of P, B, P=O; and A and B are independently selected from O, carbonyl, sulfinyl, sulfonyl, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C 10 alkenyl, substituted or unsubstituted C2-C 10 alkynyl, substituted or unsubstituted C2-C 10 cyano-containing group, aryl group.

[0007] Preferably, the sulfur-containing bicyclic compound comprises the following structure: , , , , Any one or a mixture of several of them.

[0008] Preferably, a method for preparing the chalcogenide bicyclic compound according to the above-described method involves using a sulfur source as the starting material, adding the corresponding ligand dropwise in an organic solvent environment, and continuing the reaction at a constant temperature for at least 10 hours after the addition is completed to obtain the reaction product; the chalcogenide bicyclic compound is obtained after post-treatment of the reaction product.

[0009] Preferably, the sulfur source is selected from any one or a mixture of several of methyl disulfonic acid, methyl disulfonic acid derivatives, methyl disulfonates, pyrosulfonic acid, and pyrosulfates.

[0010] Preferably, the ligand is selected from any one or a mixture of several of the following: phosphoric acid and its metal salts, pyrophosphoric acid and its metal salts, phosphoryl chloride, pyrophosphoryl chloride, phosphorous acid and its metal salts, pyrophosphorous acid and its metal salts, phosphorous chloride, pyrophosphoryl chloride, boric acid and its derivatives, and boric anhydride and its derivatives.

[0011] Preferably, the reaction solvent includes any one or a mixture of several of the following: ether organic solvents, carbonate organic solvents, carboxylic acid ester organic solvents, chlorinated hydrocarbons, alkanes, and nitrile organic solvents.

[0012] Preferably, the molar ratio of the ligand to the sulfur source is 0.8-2.5:1, more preferably 1:1; and / or the amount of the organic solvent added is 1.5-5 times the weight of the ligand, more preferably 2-3 times.

[0013] Preferably, the temperature range of the reaction is controlled between -20°C and 150°C, and the pressure range is controlled between 0.1 MPa and 5 MPa.

[0014] Preferably, the post-processing includes filtering to initially separate the liquid product; then purifying it through extraction and crystallization to obtain the sulfide bicyclic compound.

[0015] Preferably, according to the above-described application of the sulfide bicyclic compound, the sulfide bicyclic compound is added to the electrolyte of a battery; or the sulfide bicyclic compound is used as a catalyst or participates in drug molecule design.

[0016] The chalcogenide bicyclic compound provided in this application has a unique and novel cyclic structure, which is significantly different from the structure of traditional chalcogenide compounds. It adds a new member to the chalcogenide compound family and is suitable for use as an additive or catalyst in lithium-ion battery electrolytes or for participation in drug molecule design. It has important theoretical significance and practical application value. This application further proposes a method for preparing chalcogenide bicyclic compounds, which uses a specific sulfur source as the starting material to directly react with a ligand containing the target fragment to obtain the reaction product. After post-processing (separation, purification, etc.) of the reaction product, the target product can be obtained. The reaction conditions are mild and the product purity and yield are high. Detailed Implementation

[0017] This embodiment presents a chalcogenide bicyclic compound with the following structural formula: X and Y are each independently selected from any one of P, B, and P=O; and A and B are each independently selected from O, carbonyl, thionyl, thionyl, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkylene. 10 alkenyl, substituted or unsubstituted C2-C 10 Alkyne group, substituted or unsubstituted C2-C 10 Contains either a cyano group or an aryl group; more preferably, A and B are methylene groups respectively.

[0018] Preferably, in this embodiment, the chalcogenide bicyclic compound comprises the following structure: , , , , Any one or a mixture of several of them.

[0019] Preferably, this embodiment also proposes a method for preparing the chalcogenide bicyclic compound described above, using a sulfur source as the starting material, adding the corresponding ligand dropwise in an organic solvent environment to react, and continuing the reaction at a constant temperature for at least 10 hours (more preferably 10-20 hours) after the dropwise addition is completed to obtain the reaction product; the chalcogenide bicyclic compound is obtained after post-treatment of the reaction product.

[0020] Preferably, in this embodiment, the sulfur source is selected from any one or a mixture of several of methyl disulfonic acid, methyl disulfonic acid derivatives, methyl disulfate, pyrosulfonic acid, and pyrosulfate.

[0021] Preferably, in this embodiment, the ligand is selected from any one or a mixture of several of the following: phosphoric acid and its metal salts, pyrophosphoric acid and its metal salts, phosphoryl chloride, pyrophosphoryl chloride, phosphorous acid and its metal salts, pyrophosphorous acid and its metal salts, phosphorous chloride, pyrophosphoryl chloride, boric acid and its derivatives, and boric anhydride and its derivatives.

[0022] Preferably, in this embodiment, the reaction solvent includes any one or a mixture of several of the following: ether organic solvents, carbonate organic solvents, carboxylic acid ester organic solvents, chlorinated hydrocarbons, alkanes, and nitrile organic solvents. Specifically, for example, the ether organic solvent can be diethyl ether (C2H5OC2H5), tetrahydrofuran (C4H8O), etc.; the carbonate organic solvent can be dimethyl carbonate (CH3OCOOCH3); the carboxylic acid ester organic solvent can be ethyl acetate (CH3COOCH3CH3); the chlorinated hydrocarbon can be chloroform (CHCl3), dichloromethane (CH2Cl2), etc.; and the alkanes can be n-hexane (C6H5O). 14 n-Heptane C7H 16 Acetonitrile can be used for nitrile compounds.

[0023] Preferably, in this embodiment, the molar ratio of the ligand to the sulfur source is 0.8-2.5:1, more preferably 1:1; and / or the amount of organic solvent added is 1.5-5 times the weight of the ligand, more preferably 2-3 times.

[0024] Preferably, in this embodiment, the reaction temperature range is controlled between -20°C and 150°C, more preferably between 30°C and 80°C; the pressure range is controlled between 0.1 MPa and 5 MPa, more preferably, the pressure is set to atmospheric pressure.

[0025] Preferably, in this embodiment, the post-processing includes filtering to initially separate the liquid product; then, purification is carried out by extraction and crystallization to obtain a high-purity sulfide bicyclic compound. In other embodiments, other known and suitable post-processing techniques can also be used to separate and purify the reaction product, which is not an innovation of this application and is not particularly limited thereto.

[0026] Preferably, this embodiment also proposes an application of the sulfide bicyclic compound described above, in which the sulfide bicyclic compound is added to the electrolyte of a battery; or the sulfide bicyclic compound is used as a catalyst or participates in drug molecule design.

[0027] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0028] Based on the above-described implementation schemes, this application further proposes the following specific embodiments: First, it should be noted that the reagent raw materials used in the following specific embodiments and comparative examples of the present invention are sourced from the following: Unless otherwise specified, all raw materials are ordinary commercially available products.

[0029] The test methods used in the specific embodiments and comparative examples of this invention are as follows: Nuclear magnetic resonance (NMR) analysis was performed using a Bruker AVANCE II 400 MHz spectrometer. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] Example 1: A certain amount of methanedisulfonic acid (as a sulfur source) was dispersed in acetonitrile (as an organic solvent), and pyrophosphoryl chloride (as a ligand) was slowly added dropwise while maintaining the temperature at 60°C. After the addition was completed, the reaction was continued at this temperature for 12 hours. The molar ratio of pyrophosphoryl chloride to methanedisulfonic acid was 1:1, and the weight ratio of acetonitrile to pyrophosphoryl chloride was 2.5:1. After the reaction was completed, the reaction product was filtered to remove unreacted methanedisulfonic acid, yielding a filtrate (initially separating the liquid product). The filtrate was rotary evaporated until it became viscous, and petroleum ether was added for multiple extractions. The extract was further rotary evaporated until no fractions were distilled off, yielding a sulfide bicyclic compound with the following structural formula: ; The chalcogenide bicyclic compounds synthesized above were characterized by NMR (¹H, ¹³C): 1 ¹H NMR: δ 4.25 (4H, s); 13 C NMR: δ 32.3 (2C, s).

[0031] Example 2: A certain amount of methanedisulfonic acid (as a sulfur source) was dispersed in acetonitrile (as an organic solvent), and the temperature was controlled at 75°C. Phosphorous pyrophosphate chloride (as a ligand) was slowly added dropwise. After the addition was completed, the reaction was continued at this temperature for 16 hours. The molar ratio of phosphorous pyrophosphate chloride to methanedisulfonic acid was 1:1, and the weight ratio of acetonitrile to phosphorous pyrophosphate chloride was 2.5:1. After the reaction was completed, the reaction product was filtered to remove unreacted methanedisulfonic acid, yielding a filtrate (initially separating the liquid product). The filtrate was rotary evaporated until it became viscous, and petroleum ether was added for multiple extractions. The extract was further rotary evaporated until no fractions were distilled off, yielding a sulfide bicyclic compound with the following structural formula: ; The chalcogenide bicyclic compounds synthesized above were characterized by NMR (¹H, ¹³C): 1 ¹H NMR: δ 4.21 (4H, s); 13 C NMR: δ 31.5 (2C, s).

[0032] Example 3: A certain amount of methanedisulfonic acid (as a sulfur source) was dispersed in acetonitrile (as an organic solvent), and the temperature was controlled at 45°C. Tetrachloroboronic anhydride (as a ligand) was slowly added dropwise. After the addition was completed, the reaction was continued at this temperature for 18 hours. The molar ratio of tetrachloroboronic anhydride to methanedisulfonic acid was 1:1, and the weight ratio of acetonitrile to tetrachloroboronic anhydride was 2.5:1. After the reaction was completed, the reaction product was filtered to remove unreacted methanedisulfonic acid, yielding a filtrate (initially separating the liquid product). The filtrate was rotary evaporated until it became viscous, and petroleum ether was added for multiple extractions. The extract was further rotary evaporated until no fractions were distilled off, yielding a sulfide bicyclic compound with the following structural formula: ; The chalcogenide bicyclic compounds synthesized above were characterized by NMR (¹H, ¹³C): 1 ¹H NMR: δ 4.27 (4H, s); 13 C NMR: δ 31.6 (2C, s).

[0033] Example 4: A certain amount of 2-methylmethanedisulfonic acid (as a sulfur source, i.e., a methyldisulfonic acid derivative) was dispersed in acetonitrile (as an organic solvent), and the temperature was controlled at 60°C. Pyrophosphoryl chloride (as a ligand) was slowly added dropwise. After the addition was completed, the reaction was continued at this temperature for 12 hours. The molar ratio of pyrophosphoryl chloride to 2-methylmethanedisulfonic acid was 1:1, and the weight ratio of acetonitrile to pyrophosphoryl chloride was 2.5:1. After the reaction was completed, the reaction product was filtered to remove unreacted 2-methylmethanedisulfonic acid, yielding a filtrate (initially separating the liquid product). The filtrate was rotary evaporated until viscous, and petroleum ether was added for multiple extractions. The extract was further rotary evaporated until no fraction was distilled off, yielding a sulfide bicyclic compound with the following structural formula: ; The chalcogenide bicyclic compounds synthesized above were characterized by NMR (¹H, ¹³C): 1 H NMR: δ 1.38 (6H, d), 4.6 (2H, q); 13 C NMR: δ 50.58 (2C), 20.70 (2C).

[0034] Example 5: A certain amount of 2-ethylmethanedisulfonic acid (as a sulfur source, i.e., a methyl disulfonic acid derivative) was dispersed in acetonitrile (as an organic solvent), and the temperature was controlled at 60°C. Pyrophosphoryl chloride (as a ligand) was slowly added dropwise. After the addition was completed, the reaction was continued at this temperature for 30 hours. The molar ratio of pyrophosphoryl chloride to 2-ethylmethanedisulfonic acid was 1:1, and the weight ratio of acetonitrile to pyrophosphoryl chloride was 2.5:1. After the reaction was completed, the reaction product was filtered to remove unreacted 2-ethylmethanedisulfonic acid, yielding a filtrate (initially separating the liquid product). The filtrate was rotary evaporated until it became viscous, and petroleum ether was added for multiple extractions. The extract was further rotary evaporated until no fractions were distilled off, yielding a sulfide bicyclic compound with the following structural formula: ; The chalcogenide bicyclic compounds synthesized above were characterized by NMR (¹H, ¹³C): 1 H NMR: δ 4.77 (2H, t), 1.90 (4H, m), 0.91 (6H, t).; 13 C NMR: δ 50.58 (2C), 28.80 (2C), 11.50 (2C).

[0035] Comparative Example 1: This Comparative Example 1 uses the following compound provided in the example of prior patent application CN119381518A: .

[0036] The purity and yield of the products from Examples 1-5 are shown in Table 1 below:

[0037] As can be seen from Table 1 above, the reaction conditions proposed in this application are mild, and the product purity and yield are high.

[0038] To further verify the application effects achieved in Embodiments 1-5 of this application, the following comparative application experiments were conducted on the products provided in Embodiments 1-5 and Comparative Example 1 respectively: The pouch cells corresponding to Examples 1-5 and Comparative Example 1 were fabricated according to the following steps: Electrolyte preparation: Prepared in a glove box under N2 atmosphere; the water content of the organic solvent system is <10 ppm; the electrolyte includes: The organic solvent system with a mass fraction of 84.5% is specifically composed of diethyl carbonate (DEC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) in a mass ratio of 1:1:1 (wt%). The lithium salt system uses 1.0 mol·L⁻¹ -1 Lithium hexafluorophosphate (LiPF6); The products provided in Examples 1-5 and Comparative Example 1 were selected respectively, and the product accounted for 2% of the electrolyte by mass. The rest are other additives, specifically composed of ethylene carbonate (VC): lithium difluorooxalate borate (LiODFB): propanesulfonate lactone (PS) = 2:1:1 (wt%). After the raw materials of the organic solvent system are mixed evenly in a fixed ratio, the mixture is frozen and cooled for 1.5-2 hours to obtain an organic solvent mixture. The lithium salt system is added and mixed evenly. Finally, the products provided in Examples 1-5 and Comparative Example 1, as well as other additives, are added and mixed evenly for later use.

[0039] Preparation of the battery positive electrode: Using methylpyrrolidone (NMP) as a solvent, 2% (w / w) of polyvinylidene fluoride (PVDF) was uniformly dispersed to obtain a mixture. Then, 2% (w / w) of carbon nanotubes (CNTs) were added and uniformly mixed. Next, 96% (w / w) of the positive electrode active material (lithium cobalt oxide, LiCoO2) was added and mixed uniformly. The mixture was then uniformly coated onto aluminum foil using a coating machine. After drying, rolling, and cutting, the positive electrode sheet was formed with an areal density ranging from 350-450 g / cm³. 2 (Double-sided); Preparation of the battery negative electrode: Using deionized water as a solvent, 1% by mass of carboxymethyl cellulose (CMC) is uniformly dispersed to obtain a mixture. Then, 2% by mass of conductive carbon black (SP) and 96% by mass of negative electrode active material (specifically, vapor-deposited silicon carbon, material type SH-SO2) are added and uniformly mixed. Finally, 1% by mass of styrene-butadiene rubber (SBR) is added and uniformly mixed. After uniform mixing, the mixture is evenly coated onto copper foil using a coating machine. After drying, rolling, and cutting, the negative electrode sheet is formed with an areal density ranging from 200-350 g / cm³. 2 (Double-sided); To further demonstrate the effectiveness of the implementation, this application also includes the following comparative examples 2-6: Comparative Example 2: The rest of the technical solutions of Comparative Example 2 are the same as those of Example 1, except that the product in Example 1 is replaced with the additive fluoroethylene carbonate (FEC).

[0040] Comparative Example 3: The rest of the technical solutions of Comparative Example 3 are the same as those of Example 2, except that the product in Example 2 is replaced with the additive vinyl sulfate DTD.

[0041] Comparative Example 4: The remaining technical solutions of Comparative Example 4 are the same as those of Example 3, except that the product in Example 3 is replaced with the additive fluoroethylene carbonate (FEC).

[0042] Comparative Example 5: The remaining technical solutions of Comparative Example 5 are the same as those of Example 4, except that the product in Example 4 is replaced with the additive fluoroethylene carbonate (FEC).

[0043] Comparative Example 6: The rest of the technical solutions of Comparative Example 6 are the same as those of Example 5, except that the product in Example 5 is replaced with the additive fluoroethylene carbonate (FEC).

[0044] Therefore, we obtained pouch cells assembled from electrolytes provided in Examples 1-5 and Comparative Examples 1-6, respectively, using the products provided as specific additives. The electrolyte usage for each pouch cell was 25g. Then, the following performance comparison tests were conducted on each pouch cell: Three groups of each soft-pack battery corresponding to Examples 1-5 and Comparative Examples 1-6 were made. Each group was cycled 200 times at 25°C, 45°C and 60°C respectively. The charge and discharge conditions used for each cycle test were: charge and discharge rate of 1C / 1C and voltage range of 2.5V-4.2V. The measured capacity retention rates of the lithium-ion batteries are shown in Table 2 below:

[0045] It should be noted that the thiodicyclic bicyclic compounds provided in this embodiment can also be used as catalysts or participate in drug molecule design, and have good application prospects.

[0046] To further enhance the effectiveness of the sulfide bicyclic compound proposed in the above embodiments of this application in lithium-ion batteries, this embodiment also proposes an electrolyte for lithium iron phosphate batteries, comprising an organic solvent system, a lithium salt system, and an additive system; the organic solvent system comprises at least one cyclic carbonate and at least one chain carbonate; the additive system comprises a sulfide bicyclic compound, wherein the sulfide bicyclic compound is the sulfide bicyclic compound described above in this embodiment.

[0047] Preferably, in this embodiment, the sulfide bicyclic compound accounts for 0.5-5% of the electrolyte mass fraction of the lithium-ion battery; more preferably, it is 1-4%.

[0048] Preferably, in this embodiment, the cyclic carbonate accounts for 15-35% of the mass fraction of the electrolyte in the lithium-ion battery; the chain carbonate accounts for 55-75% of the mass fraction of the electrolyte in the lithium-ion battery; preferably, in this embodiment, the cyclic carbonate is ethylene carbonate EC and / or propylene carbonate PC; the chain carbonate is ethyl methyl carbonate EMC and / or dimethyl carbonate DMC and / or diethyl carbonate DEC.

[0049] Preferably, in this embodiment, the lithium salt system includes any one or a mixture of several of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalateborate)borate (LiBOB), and lithium tetrafluoroborate (LiBF4); preferably, in this embodiment, the concentration of the lithium salt system in the electrolyte of the lithium iron phosphate battery is 0.8-1 mol·L⁻¹. -1 .

[0050] Preferably, in this embodiment, the additive system further includes the combined use of at least two of the following: lithium difluorooxalate borate (LiODFB), ethylene carbonate (VC), fluoroethylene carbonate (FEC), ethylene sulfate (DTD), and propanesulfonate lactone (PS), which account for 0.5-5% of the mass fraction of the lithium-ion battery electrolyte.

[0051] Preferably, this embodiment also proposes a method for preparing the electrolyte of a lithium iron phosphate battery as described above, wherein the raw materials of the organic solvent system are mixed to obtain an organic solvent mixture, the organic solvent mixture is frozen for 1-3 hours, a lithium salt system is added to the organic solvent mixture for mixing, and finally an additive system is added for mixing to obtain the electrolyte of the lithium-ion battery.

[0052] Preferably, this embodiment also proposes a lithium iron phosphate battery, which uses the electrolyte of the lithium iron phosphate battery as described above; its positive electrode active material includes lithium iron phosphate material LiFePO4; more preferably, in this embodiment, the negative electrode active material of the lithium iron phosphate battery includes graphite or a known carbon-silicon composite material.

[0053] To further verify the effectiveness of the electrolyte proposed in the above embodiments of this application in lithium iron phosphate batteries, this application further provides the following embodiments and comparative examples: Example 6: An electrolyte for a lithium iron phosphate battery, comprising: The organic solvent system with a mass fraction of 84.5% is specifically composed of ethylene carbonate EC: ethyl methyl carbonate EMC: dimethyl carbonate DMC = 3:5:2 (wt%). The lithium salt system uses 1.0 mol·L⁻¹ -1 Lithium hexafluorophosphate (LiPF6); Example 1 provides a product with a mass fraction of 2%; The remainder consists of other additives, specifically ethylene carbonate (VC): lithium difluorooxalate borate (LiODFB): propanesulfonate lactone (PS) = 2:1:1 (wt%). The electrolyte is prepared in a glove box under N2 atmosphere, ensuring that the water content of the solvent system is <10ppm. During preparation, the raw materials of the organic solvent system are first mixed evenly in a fixed ratio, and then the mixture is cooled to a freezing temperature of 1.5-2 hours to obtain an organic solvent mixture. The lithium salt system is then added and mixed evenly. Finally, the product provided in Example 1 and other additives are added and mixed evenly before use.

[0054] Example 7: The remaining technical solutions of Example 7 are the same as those of Example 6, except that in Example 7, the product provided in Example 2 is used instead of the product provided in Example 1.

[0055] Example 8: The remaining technical solutions of Example 8 are the same as those of Example 6, except that in Example 8, the product provided in Example 3 is used instead of the product provided in Example 1.

[0056] Example 9: The remaining technical solutions of Example 9 are the same as those of Example 6, except that in Example 9, the product provided in Example 4 is used instead of the product provided in Example 1.

[0057] Example 10: The remaining technical solutions of Example 10 are the same as those of Example 6, except that in Example 10, the product provided in Example 5 is used instead of the product provided in Example 1.

[0058] Comparative Example 7: The remaining technical solutions of Comparative Example 7 are the same as those of Example 6, except that in Comparative Example 7, the product provided by Comparative Example 1 is used instead of the product provided by Example 1.

[0059] Comparative Example 8: The remaining technical solutions of Comparative Example 8 are the same as those of Example 6, except that in Comparative Example 8, the organic solvent system is specifically composed of ethylene carbonate EC: propylene carbonate PC = 1:1 (wt%).

[0060] Comparative Example 9: The remaining technical solutions of Comparative Example 9 are the same as those of Example 6, except that in Comparative Example 9, the organic solvent system is specifically composed of diethyl carbonate (DEC): ethyl methyl carbonate (EMC): dimethyl carbonate (DMC) in a mass ratio of 1:1:1 (wt%).

[0061] Then, the pouch cells corresponding to Examples 6-10 and Comparative Examples 7-9 were fabricated according to the following steps: Preparation of the battery positive electrode: Using methylpyrrolidone (NMP) as a solvent, 2% (w / w) of polyvinylidene fluoride (PVDF) was uniformly dispersed to obtain a mixture. Then, 2% (w / w) of carbon nanotubes (CNTs) were added and uniformly mixed. Next, 96% (w / w) of the positive electrode active material (lithium iron phosphate, LiFePO4) was added and mixed evenly. The mixture was then uniformly coated onto aluminum foil using a coating machine. After drying, rolling, and cutting, the positive electrode sheet was formed with an areal density ranging from 350-450 g / cm³. 2 (Double-sided); Preparation of the battery negative electrode: Using deionized water as a solvent, 1% by mass of carboxymethyl cellulose (CMC) is uniformly dispersed to obtain a mixture. Then, 2% by mass of conductive carbon black (SP) and 96% by mass of negative electrode active material (specifically graphite) are added and uniformly mixed. Finally, 1% by mass of styrene-butadiene rubber (SBR) is added and uniformly mixed. After uniform mixing, the mixture is evenly coated onto copper foil using a coating machine. After drying, rolling, and cutting, the negative electrode sheet is formed with an areal density ranging from 200-350 g / cm³. 2 (Double-sided); Therefore, we obtained: lithium iron phosphate pouch batteries assembled from the electrolytes provided by Examples 6-10 and Comparative Examples 7-9 respectively as specific additives, with each pouch battery using 25g of electrolyte. To further demonstrate the specific application effect of the embodiments of this application in lithium iron phosphate batteries, this application also provides the following embodiment 11: Example 11: The remaining technical solutions of Example 11 are the same as those of Example 6, except that in the soft-pack battery of Example 11, the positive electrode active material adopts the ternary system NCM622, wherein NCM is LiNi x Co y Mn 1-x-y The abbreviation for O2, 622, refers to the ratio of N (representing nickel), C (representing cobalt), and M (representing manganese) being 6:2:2.

[0062] Then, the following performance comparison tests were conducted on each pouch battery: Three groups of each soft-pack battery corresponding to Examples 6-11 and Comparative Examples 7-9 were made. Each group was cycled for 200 cycles at 25°C, 45°C and 60°C respectively. The charge and discharge conditions used for each cycle test were: charge and discharge rate of 1C / 1C and voltage range of 2.5V-4.2V. The measured capacity retention rates of lithium-ion batteries are shown in Table 3 below:

[0063] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0064] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A chalcogenide bicyclic compound, characterized in that, It contains the following structural formula: X and Y are each independently selected from any one of P, B, and P=O; and A and B are each independently selected from O, carbonyl, thionyl, thionyl, substituted or unsubstituted C1-C6 alkylene, substituted or unsubstituted C2-C6 alkylene. 10 alkenyl, substituted or unsubstituted C2-C 10 Alkyne group, substituted or unsubstituted C2-C 10 Contains either a cyano group or an aryl group.

2. The chalcogenide bicyclic compound according to claim 1, characterized in that, The chalcogenide bicyclic compound comprises the following structure: , , , , Any one or a mixture of several of them.

3. A method for preparing a chalcogenide bicyclic compound according to any one of claims 1-2, characterized in that, Using a sulfur source as the starting material, the corresponding ligand is added dropwise in an organic solvent environment to carry out the reaction. After the addition is completed, the reaction is continued at a constant temperature for at least 10 hours to obtain the reaction product. The reaction product is then post-treated to obtain the sulfide bicyclic compound.

4. The method for preparing the chalcogenide bicyclic compound according to claim 3, characterized in that, The sulfur source is selected from any one or a mixture of several of the following: methyl disulfonic acid, methyl disulfonic acid derivatives, methyl disulfonates, pyrosulfonic acid, and pyrosulfates.

5. The method for preparing the chalcogenide bicyclic compound according to claim 3, characterized in that, The ligand is selected from any one or a mixture of several of the following: phosphoric acid and its metal salts, pyrophosphate and its metal salts, phosphoryl chloride, pyrophosphoryl chloride, phosphorous acid and its metal salts, pyrophosphorous acid and its metal salts, phosphorous chloride, pyrophosphoryl chloride, boric acid and its derivatives, and boric anhydride and its derivatives.

6. The method for preparing the chalcogenide bicyclic compound according to claim 3, characterized in that, The reaction solvent includes any one or a mixture of several of the following: ether organic solvents, carbonate organic solvents, carboxylic acid ester organic solvents, chlorinated hydrocarbons, alkanes, and nitrile organic solvents.

7. The method for preparing the chalcogenide bicyclic compound according to claim 3, characterized in that, The molar ratio of the ligand to the sulfur source is 0.8-2.5:1, preferably 1:1; and / or the amount of the organic solvent added is 1.5-5 times the weight of the ligand, preferably 2-3 times.

8. The method for preparing the chalcogenide bicyclic compound according to claim 3, characterized in that, The temperature range of the reaction is controlled between -20℃ and 150℃, and the pressure range is controlled between 0.1MPa and 5MPa.

9. The method for preparing the chalcogenide bicyclic compound according to claim 3, characterized in that, The post-processing includes filtering to initially separate the liquid product; then purifying it through extraction and crystallization to obtain the sulfide bicyclic compound.

10. The application of a chalcogenide bicyclic compound according to any one of claims 1-2, characterized in that, The chalcogenide bicyclic compound may be added to the electrolyte of a battery; or the chalcogenide bicyclic compound may be used as a catalyst or involved in drug molecule design.

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