A boron-containing electrolyte salt and preparation and use thereof

Abstract

The application discloses a boron-containing electrolyte salt and a preparation and application thereof, and the preparation method of the boron-containing electrolyte salt comprises the following steps: I, adding boric acid, A + HCO3 ‑ , and water into a reaction container, stirring and mixing, then adding salicylic acid, obtaining a boron-containing electrolyte salt reaction liquid after reaction, and obtaining a product, the boron-containing electrolyte salt, through post-treatment of the boron-containing electrolyte salt reaction liquid; the A + is a 1-ethyl-3-methyl imidazole cation or a 1,2,3,4-tetramethyl imidazoline cation. The boron-containing electrolyte salt can be applied to a capacitor electrolyte as an electrolyte additive. The application has the advantages that a novel boron-containing electrolyte salt structure which can be applied to a capacitor electrolyte as an electrolyte additive is provided, the boron electrolyte salt has a simple synthesis process route, mild reaction conditions, convenient operation, high product purity, high yield, and high industrial utilization value.

Description

Technical Field

[0001] This invention specifically relates to the field of novel compounds and their preparation technology. Background Technology

[0002] Boron-containing electrolytes are a novel material that can be used as additives in lithium-ion battery electrolytes. Studies have found that boron compounds exhibit design diversity, and their unique structures enhance lithium-ion migration within the electrolyte, resulting in higher lithium-ion transference numbers, better thermal stability, and a more stable solid-electrolyte interface. This, in turn, improves the electrochemical performance of capacitors, including storage capacity, high-temperature resistance, and cycle life. To further enhance electrolyte performance, various boron compounds are continuously being researched as novel electrolyte additives for capacitor electrolytes.

[0003] N-substituted imidazole / imidazoline-bis(salicylic acid) borates are novel boron-containing electrolyte salts. Their cations are N-substituted imidazole / imidazoline salts, and their anions are halogen-free chelated bis(salicylic acid) borates. The strong π-π stacking and CH...π interactions between the benzene ring of the anion and the aromatic ring of the cation generally give these organic borate ionic liquids excellent lubrication and high-temperature resistance, making them suitable for the preparation of high-temperature lithium-ion battery systems. Therefore, these boron-containing electrolyte salts have promising market applications.

[0004] US Patent document (US20040007693A1) discloses a synthesis process for 1-butyl-3-methylimidazolium-bissalicylic acid borate. The process involves synthesizing the intermediate lithium bissalicylic acid borate in an aqueous system using boric acid, lithium carbonate, and salicylic acid. This intermediate is then ion-exchanged with 1-butyl-3-methylimidazolium chloride under heating conditions to obtain crude 1-butyl-3-methylimidazolium-bissalicylic acid borate. After washing and drying, a liquid product is obtained. The disadvantages of this method are: the reaction process is cumbersome and complex; the introduction of lithium salt in the first step increases the difficulty of purification and the cost of raw materials; and the introduction of excessively high chloride content in the second step not only corrodes production equipment and pollutes the environment but also leads to a decline in the electrical performance of capacitors, accelerating their failure time. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a boron-containing electrolyte salt, its preparation method and application. The preparation method uses readily available raw materials, has a simple reaction, is easy to purify, has low cost, and produces a product with high purity suitable for industrial application. The boron-containing electrolyte salt can be used as an electrolyte additive in capacitor electrolytes.

[0006] The method of this invention is a one-step synthesis method with a short synthetic route, mild reaction conditions, simple purification process, and no use of toxic or harmful solvents. The obtained product has high yield and high purity. The reaction uses water as a solvent, and the entire production process does not produce any substances harmful to the environment, meeting the requirements for green and environmentally friendly production and emissions. Therefore, the following technical solution is formed: A boron-containing electrolyte salt has the following structural formula: , Where A + It is a 1-ethyl-3-methylimidazolium cation or a 1,2,3,4-tetramethylimidazoline cation.

[0007] A method for preparing a boron-containing electrolyte salt includes the following steps: 1. Adding boric acid and A... + HCO3 - Water is added to a reaction vessel and stirred to mix. Then salicylic acid is added. After the reaction is complete, a boron-containing electrolyte salt reaction solution is obtained. The boron-containing electrolyte salt reaction solution is then post-treated to obtain the product boron-containing electrolyte salt. The A... + It is a 1-ethyl-3-methylimidazolium cation or a 1,2,3,4-tetramethylimidazoline cation.

[0008] Furthermore, in the aforementioned method for preparing a boron-containing electrolyte salt, A + HCO3 - The molar ratio of boric acid and salicylic acid is (1~1.2): (1~1.2): 2.

[0009] Furthermore, in the aforementioned method for preparing boron-containing electrolyte salt, water is used as a reaction solvent, and the amount of water added ensures that the reaction concentration is 25-30% relative to the theoretical amount of boron-containing electrolyte salt produced.

[0010] Furthermore, in the aforementioned method for preparing a boron-containing electrolyte salt, boric acid and A... + HCO3 - After adding water to the reaction vessel, heat to 40-60℃ and stir thoroughly. Then add salicylic acid in batches and maintain the temperature at 60-80℃ for 4-8 hours. The purpose of adding salicylic acid in batches is to prevent the instantaneous generation of a large amount of heat and gas when adding salicylic acid all at once, which would cause the reaction to boil over and the material to spray out.

[0011] Furthermore, in the aforementioned method for preparing a boron-containing electrolyte salt, the post-treatment step of the boron-containing electrolyte salt reaction solution includes: adding solvent for extraction 2-3 times, followed by vacuum concentration and deep drying for 12-24 hours to obtain a boron-containing electrolyte salt solid.

[0012] Furthermore, in the aforementioned method for preparing a boron-containing electrolyte salt, the organic solvent used for extraction is selected from any one of dichloromethane, ethyl acetate, and dimethyl carbonate.

[0013] The above-mentioned boron-containing electrolyte salt is used as an electrolyte additive in capacitor electrolytes.

[0014] The advantages of this invention are: This application provides a novel boron-containing electrolyte salt structure and a method for preparing the boron-containing electrolyte salt. The synthesis process is simple, the reaction conditions are mild, water is used as the reaction solvent, the operation is convenient, and no complex equipment is required. No toxic products are generated during the reaction, the entire reaction process is safe and environmentally friendly, and the synthesized product has high purity, reaching up to 99.9%. It can be directly used as an electrolyte additive with a high yield. This novel boron-containing electrolyte salt can be used as an electrolyte additive in capacitor electrolytes, thus having high industrial application value. Attached Figure Description

[0015] Figure 1 The 1H spectrum is of 1-ethyl-3-methylimidazolium disalicylate borate prepared in Example 1.

[0016] Figure 2 The B spectrum is of 1-ethyl-3-methylimidazolium disalicylate borate prepared in Example 1.

[0017] Figure 3 The 1H spectrum is of 1,2,3,4-tetramethylimidazoline disalicylic acid borate prepared in Example 3.

[0018] Figure 4 The B spectrum is for the 1,2,3,4-tetramethylimidazoline disalicylic acid borate prepared in Example 3.

[0019] Figure 5 This is a thermogravimetric analysis (TGA) curve of 1-ethyl-3-methylimidazolium disalicylate borate in carbonate solvents. Detailed Implementation

[0020] The present invention will now be described in further detail with reference to preferred embodiments.

[0021] Example 1: 1. 1.1 mol of boric acid, 1.0 mol of 1-ethyl-3-methylimidazolium bicarbonate, and 51.1 mol of water were added to a reaction vessel and stirred thoroughly. The mixture was heated to 50°C, and 2 mol of salicylic acid was added to the reaction vessel in batches while stirring. After the addition was completed, the temperature was raised to 80°C and the reaction was maintained for 6 hours to obtain a reaction solution of lithium 1-ethyl-3-methylimidazolium disalicylate borate. The reaction solution was added to dichloromethane, extracted twice, concentrated under vacuum, and deep dried for 12 hours to obtain 0.81 mol of 1-ethyl-3-methylimidazolium disalicylate borate.

[0022] The reaction principle is as follows: .

[0023] Combined with NMR ¹H and ¹B spectral analysis, the product purity was 99.9%, and the yield reached 81%. The ¹H spectrum showed... Figure 1 As shown, the B spectrum is as follows Figure 2 As shown.

[0024] According to ICP testing: Na + 0.01ppm, K + 0.01ppm, Fe 3+ 0.01ppm, Ca 2+ 0.01ppm, Pb 2+ : 0.02ppm.

[0025] Potentiometric titration: Cl - : 0.03ppm.

[0026] Moisture content determined by Karl Fischer titration: 74 ppm.

[0027] Example 2: 1. 1.2 mol of boric acid, 1.1 mol of 1-ethyl-3-methylimidazolium bicarbonate, and 65.7 mol of water were added to a reaction vessel and stirred thoroughly. The mixture was heated to 60°C, and 2 mol of salicylic acid was added to the reaction vessel in batches while stirring. After the addition was completed, the temperature was raised to 80°C and the reaction was maintained for 7 hours to obtain a reaction solution of lithium 1-ethyl-3-methylimidazolium disalicylate borate. The reaction solution was added to dichloromethane, extracted twice, concentrated under vacuum, and dried for 16 hours to obtain 0.80 mol of 1-ethyl-3-methylimidazolium disalicylate borate.

[0028] Combined with NMR ¹H and ¹B spectroscopy analysis, the product purity was found to be 99.9%, with a yield of 80%. According to ICP testing: Na + 0.02ppm, K + 0.01ppm, Fe 3+ 0.02ppm, Ca 2+ 0.01ppm, Pb 2+ : 0.03ppm.

[0029] Potentiometric titration: Cl - : 0.11ppm.

[0030] Moisture content determined by Karl Fischer titration: 90 ppm.

[0031] Example 3: 1.1 mol of boric acid, 1.2 mol of 1,2,3,4-tetramethylimidazoline bicarbonate, and 68.4 mol of water were added to a reaction vessel and stirred thoroughly. The mixture was heated to 40°C, and 2 mol of salicylic acid was added to the reaction vessel in batches while stirring. After the addition was completed, the temperature was raised to 60°C and the reaction was maintained for 8 hours to obtain a reaction solution of lithium 1,2,3,4-tetramethylimidazoline disalicylate borate. Dimethyl carbonate was added to the reaction solution, and the mixture was extracted three times, concentrated under vacuum, and dried for 24 hours to obtain 0.78 mol of 1,2,3,4-tetramethylimidazoline disalicylate borate.

[0032] The reaction principle is as follows: .

[0033] Combined with NMR ¹H and ¹B spectral analysis, the product purity was 99.9%, and the yield reached 78%. ¹H spectral data are as follows: Figure 3 As shown, the B spectrum is as follows Figure 4 As shown.

[0034] According to ICP testing: Na + 0.01ppm, K + 0.01ppm, Fe 3+ 0.02ppm, Ca 2+ 0.01 ppm, Pb 2+ : 0.01ppm.

[0035] Potentiometric titration: Cl - 0.78ppm.

[0036] Moisture content determined by Karl Fischer titration: 149 ppm.

[0037] Example 4: 1.0 mol of boric acid, 1.2 mol of 1,2,3,4-tetramethylimidazoline bicarbonate, and 53.2 mol of water were added to a reaction vessel and stirred thoroughly. The mixture was heated to 50°C, and 2 mol of salicylic acid was added to the reaction vessel in batches while stirring. After the addition was completed, the temperature was raised to 70°C and the reaction was maintained for 7 hours to obtain a reaction solution of lithium 1,2,3,4-tetramethylimidazoline disalicylate borate. The reaction solution was added to ethyl acetate, extracted three times, concentrated under vacuum, and dried for 18 hours to obtain 0.79 mol of 1,2,3,4-tetramethylimidazoline disalicylate borate.

[0038] Combined with NMR H and B spectrum analysis, the product purity was 99.9% and the yield reached 79%.

[0039] According to ICP testing: Na + 0.02ppm, K + 0.03ppm, Fe3+ 0.04ppm, Ca 2+ 0.09 ppm, Pb 2+ : 0.02ppm.

[0040] Potentiometric titration: Cl - : 0.23ppm.

[0041] Moisture content determined by Karl Fischer titration: 98 ppm.

[0042] As can be seen from the above embodiments, this invention provides a novel boron-containing electrolyte salt structure and a method for preparing the boron-containing electrolyte salt. The synthesis process is simple, the reaction conditions are mild, and the operation is convenient. It can be obtained without the use of complex equipment. No toxic products are generated during the reaction process. The entire reaction process is safe and environmentally friendly. The synthesized product has high purity, reaching up to 99.9%, and can be directly used as an electrolyte additive. It also has a high yield and high industrial utilization value.

[0043] Electrochemical performance tests were conducted on 1-ethyl-3-methylimidazolium disalicylate borate and 1,2,3,4-tetramethylimidazoline disalicylate borate in several different solvent systems. The results showed that both novel borates exhibited good solubility in carbonate solvents, high ionic conductivity, and high decomposition temperatures. For example, 1-ethyl-3-methylimidazolium disalicylate borate showed good solubility in carbonate solvents, an ionic conductivity >8.0 mS / cm, and a decomposition temperature >400℃. (See [link to relevant documentation] for details.) Figure 5 As shown, the boron-containing electrolyte salt described in this application can be used as an electrolyte additive in capacitor electrolytes. This demonstrates that the boron-containing electrolyte salt can be used as an electrolyte additive in capacitor electrolytes.

[0044] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A boron-containing electrolyte salt, characterized in that, The structure is as follows: , Among them, A + Represents a cation; the A + It is a 1-ethyl-3-methylimidazolium cation or a 1,2,3,4-tetramethylimidazoline cation.

2. A method for preparing a boron-containing electrolyte salt, comprising the following steps: I. Adding boric acid, A... + HCO3 - Water is added to a reaction vessel and stirred to mix. Then salicylic acid is added. After the reaction is complete, a boron-containing electrolyte salt reaction solution is obtained. The boron-containing electrolyte salt reaction solution is then post-treated to obtain the product boron-containing electrolyte salt. The A... + It is a 1-ethyl-3-methylimidazolium cation or a 1,2,3,4-tetramethylimidazoline cation.

3. The method for preparing a boron-containing electrolyte salt according to claim 2, characterized in that: A + HCO3 - The molar ratio of boric acid and salicylic acid is (1~1.2): (1~1.2):

2.

4. The method for preparing a boron-containing electrolyte salt according to claim 2, characterized in that: Water is used as the reaction solvent, and its dosage ensures that the reaction concentration is 25-30% relative to the theoretical amount of boron-containing electrolyte salt produced.

5. The method for preparing a boron-containing electrolyte salt according to claim 2, characterized in that: Boric acid, A + HCO3 - After adding water to the reaction vessel, heat to 40-60℃ and stir thoroughly. Then add salicylic acid in batches and keep the temperature at 60-80℃ for 4-8 hours.

6. The method for preparing a boron-containing electrolyte salt according to claim 2, characterized in that: The post-processing steps of the boron-containing electrolyte salt reaction solution include: adding solvent for extraction 2-3 times, followed by vacuum concentration and deep drying for 12-24 hours to obtain boron-containing electrolyte salt solid.

7. The method for preparing a boron-containing electrolyte salt according to claim 6, characterized in that: The organic solvent used for extraction is selected from any one of dichloromethane, ethyl acetate, or dimethyl carbonate.

8. The application of the boron-containing electrolyte salt as described in claim 1 as an electrolyte additive in capacitor electrolytes.

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