Lithium trifluoromethylsulfinate and its preparation method and application
The high-purity lithium trifluoromethyl sulfinate is produced by completing the CS bond construction and lithium salting in one step at room temperature through photocatalytic reaction, which solves the problems of high preparation cost, complex process and heavy environmental burden in the existing technology, and realizes low-cost and efficient large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZIBO FEIYUAN CHEM CO LTD
- Filing Date
- 2026-04-10
- Publication Date
- 2026-07-24
AI Technical Summary
The existing technology for preparing lithium trifluoromethyl sulfinate is characterized by high cost, complex process, low yield, and heavy environmental impact, making it difficult to achieve large-scale production.
A photocatalytic reaction was carried out in a mixed solvent using sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate. Trifluoromethane was used as a trifluoromethyl radical precursor. The CS bond construction and lithium salting were completed in one step at room temperature through photo-irradiation to generate high-purity lithium trifluoromethyl sulfinate.
It reduces raw material costs, simplifies reaction steps, improves product purity and yield, reduces environmental pollution, and achieves high production efficiency and safety, making it suitable for large-scale production.
Smart Images
Figure CN121990950B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of organofluorine chemical technology, specifically relating to lithium trifluoromethyl sulfinate, its preparation method, and its application. Background Technology
[0002] Lithium trifluoromethyl sulfinate (CF3SO2Li) is a fluorinated lithium salt with unique physicochemical properties. Its molecular structure combines the strong electron-withdrawing properties of trifluoromethyl with the ionic conductivity of lithium sulfinate. With its excellent electrochemical stability, good solubility and compatibility with various materials, it has shown broad application prospects in new energy, pharmaceuticals, chemical industry, materials science and other fields, and has irreplaceable value in the field of lithium-ion batteries.
[0003] In the field of lithium-ion batteries, lithium trifluoromethyl sulfinate, as a novel lithium carrier molecule, can achieve precise replenishment of lithium ions, effectively solving the capacity decay problem caused by the loss of active lithium ions in lithium batteries, and significantly extending battery service life. At the same time, it is stable in air, has a relatively low synthesis cost, and is perfectly compatible with graphite, silicon-carbon anodes and various cathode materials. It can be widely used in electric vehicles, energy storage power stations and other scenarios, providing key technical support for the upgrading and development of the lithium battery industry.
[0004] Currently, the main method for preparing lithium trifluoromethylsulfinate is the reaction of prefunctionalized, highly reactive fluorine-containing reagents with sulfites. CN120817877A discloses a trifluoromethylsulfonyl chloride method, which uses trifluoromethylsulfonyl chloride and lithium sulfite as raw materials. A nucleophilic substitution reaction is carried out in an organic solvent, where the sulfite anion attacks the sulfur atom in the sulfonyl chloride to generate lithium trifluoromethylsulfinate. The product is then obtained through filtration, concentration, and recrystallization. This method has a relatively direct reaction path and is convenient for small-scale laboratory preparations, but its large-scale production is difficult due to limitations in the characteristics of the raw materials.
[0005] CN120794890A describes a trifluoromethyl sulfinate conversion method. Using sodium trifluoromethyl sulfinate as the starting material, it first undergoes an alkylation reaction with a benzyl halide to generate S-benzyl trifluoromethyl sulfinate. Subsequently, a hydrogenation reduction reaction is carried out in the presence of a catalyst to remove the benzyl group. Finally, lithium trifluoromethyl sulfinate is obtained through lithium salt substitution. This method requires multiple reaction steps and separation and purification processes, making the reaction process relatively complex.
[0006] Therefore, existing technologies suffer from high production costs due to their reliance on prefunctionalized, highly reactive fluorinated reagents, such as trifluoromethanesulfonyl chloride or sodium trifluoromethanesulfinate. These reagents involve complex synthesis processes and demanding reaction conditions, leading to high market prices and directly increasing the production cost of lithium trifluoromethanesulfinate. Secondly, the reaction processes are complex and yields are low, particularly with the trifluoromethanesulfinate conversion method, which involves multiple steps including alkylation, hydrogenation reduction, and lithium salt replacement. Each step requires strict control of reaction conditions and separate separation and purification operations. Finally, the environmental burden is significant, as each separation and purification step generates large amounts of organic wastewater. Improper treatment of this wastewater can pollute soil, water bodies, and other environmental environments. Summary of the Invention
[0007] The technical problem to be solved by this invention is to overcome the technical defects of existing technologies in the preparation of lithium trifluoromethyl sulfinate, such as high production cost, complex reaction process, low yield and heavy environmental burden. The invention provides a lithium trifluoromethyl sulfinate, its preparation method and application. The preparation method is efficient, low cost and environmentally friendly. The prepared lithium trifluoromethyl sulfinate has high purity and high yield. Its application is that it can effectively replenish the active lithium ions lost in the battery, significantly restore the battery capacity and extend the battery cycle life.
[0008] The preparation method of lithium trifluoromethyl sulfite according to the present invention includes the following steps: First, sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate are mixed and dissolved in a solvent to obtain a homogeneous and stable reaction system. The system is then subjected to deoxygenation treatment (preferably by purging with high-purity nitrogen 3-5 times to completely remove oxygen from the system and avoid oxygen interfering with the reaction process and generating oxidation byproducts); then, trifluoromethane gas is introduced into the deoxygenated system, and the reaction pressure is controlled at 0.4~1.0 MPa (this pressure range ensures that trifluoromethane is contained within the reaction system). The system has suitable solubility, which can ensure the reaction rate and avoid the increased equipment cost and safety risks caused by high pressure; turn on the visible light source and control the wavelength of the light source to 400~430nm (this wavelength range matches the absorption wavelength of tetrabutylammonium decatungstate, which can maximize the activation of the photocatalyst and achieve efficient CH bond breaking. The photo-reaction is carried out at room temperature, so that the components can fully react to generate the target product and obtain the reaction solution; finally, the reaction solution is post-processed to remove impurities and separate and purify to obtain high-purity lithium trifluoromethyl sulfinate.
[0009] In the reaction system of this invention, trifluoromethane, as a precursor of the trifluoromethyl radical, can be purified from a crude industrial byproduct. Sodium sulfite acts as a scavenger for the trifluoromethyl radical in the system; lithium carbonate is selected as the lithium source to provide lithium ions and achieve in-situ lithium salting of the product. The photocatalyst is a hydrogen atom transfer photocatalyst, whose core function is to selectively activate the CH bond of trifluoromethane, preferably tetrabutylammonium decatungstate, whose excited state can extract hydrogen atoms from trifluoromethane to generate trifluoromethyl radicals. Sodium ascorbate is selected as the electron donor to reduce and regenerate the photocatalyst, maintain the catalytic cycle, and provide electrons for the subsequent radical reduction step. The solvent is a mixture of acetonitrile and water, with acetonitrile as the main solvent to dissolve the organic components and water to dissolve the sodium sulfite.
[0010] The preparation method of this invention involves sequentially adding measured amounts of sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate to a high-pressure photoreactor, dissolving them in a mixed solvent of acetonitrile and water in a preferred ratio. After sealing the reactor, the air inside the reactor is replaced three times with high-purity nitrogen to remove oxygen. Then, trifluoromethane gas is introduced into the reactor, and the pressure inside the reactor is controlled to 0.4~1.0 MPa. Stirring is started, and a visible light source with a wavelength of 400~430 nm is turned on. The reaction is carried out under photoirradiation at room temperature for 6~12 hours. The reaction solution is concentrated to a viscous state by rotary evaporation, and the product is dissolved in anhydrous ethanol. The insoluble inorganic salts are removed by filtration. The filtrate is concentrated again, and recrystallization is carried out in a mixed solvent of acetonitrile and toluene. After cooling, white crystals precipitate. The crystals are collected by filtration and dried under vacuum at 100~120℃ for 12 hours to obtain lithium trifluoromethyl sulfinate product.
[0011] This invention utilizes a hydrogen atom transfer photocatalyst to generate a strongly oxidizing excited state under illumination, extracting a hydrogen atom from a trifluoromethane molecule to achieve homolytic cleavage of its CH bond, generating a highly reactive trifluoromethyl radical. This radical is immediately captured by sodium sulfite in the system, forming a trifluoromethanesulfonyl radical. The reduced photocatalyst is oxidized and regenerated by an electron donor added to the system. Simultaneously, the electron provided by the electron donor is transferred through the reduced photocatalyst, allowing the trifluoromethanesulfonyl radical to gain an electron and transform into a trifluoromethanesulfinate anion, which then combines with a lithium ion provided by lithium carbonate to generate the target product, lithium trifluoromethanesulfinate. The entire process completes the construction of the CS bond and lithium salting in one step under mild conditions, without the need for prefunctionalized fluorine-containing reagents.
[0012] The preparation of the target product can be achieved by making reasonable adjustments to the above core steps according to actual production needs. For example, deoxygenation can be carried out using conventional deoxygenation methods such as high-purity nitrogen replacement or vacuum degassing, as long as the oxygen in the system can be completely removed; the photo-reaction can use conventional visible light sources such as LED visible light sources or mercury lamps, as long as the wavelength of the light source is controlled within the range of 400~430nm; the reaction vessel can be a conventional high-pressure photoreactor, and the material can be stainless steel, polytetrafluoroethylene, or other materials that are resistant to high pressure, corrosion and do not affect the reaction.
[0013] First, sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate are dissolved in a solvent consisting of acetonitrile and water at a volume ratio of 4:1 to 1:1. Acetonitrile is a polar organic solvent that effectively dissolves the organic-inorganic components such as sodium sulfite, tetrabutylammonium decatungstate, and sodium ascorbate, while also increasing the solubility of trifluoromethane. The addition of water adjusts the polarity of the reaction system, promotes the dissociation of sodium sulfite, provides a suitable proton environment for the reaction, and reduces the viscosity of the system, facilitating the transfer of substances during the reaction. Too low a water content leads to insufficient dissociation of sodium sulfite, a decreased reaction rate, and increased system viscosity, affecting the transfer of active species. Too high a water content reduces the solubility of trifluoromethane and may also reduce the activity of the photocatalyst, generating more byproducts. Further optimized, the volume ratio of acetonitrile to water is 4:1 to 2:1, at which point the reaction rate, product yield, and purity are all at their best levels.
[0014] The light-induced reaction can proceed at room temperature for 6-12 hours without the need for additional heating or cooling equipment, which significantly reduces production energy consumption and equipment costs. At the same time, it avoids the adverse effects of high or low temperatures on the reaction. High temperatures can cause trifluoromethane to volatilize, reducing the utilization rate of raw materials and potentially triggering side reactions; low temperatures will significantly reduce the reaction rate, prolong the reaction time, and increase production costs.
[0015] The specific post-processing steps are as follows: evaporate and concentrate the reaction solution to a viscous state (preferably by rotary evaporation concentration), add anhydrous ethanol to dissolve, filter to remove insoluble inorganic salts (mainly unreacted lithium carbonate, sodium sulfate generated in the reaction, etc.), concentrate the filtrate again to a viscous state, add a mixed solvent for recrystallization, cool to 0~5℃ and stand for 2~4h to precipitate white crystals, filter and collect the white crystals, and vacuum dry at 100~120℃ for 12h.
[0016] The mixed solvent is a mixture of acetonitrile and toluene, with a volume ratio of acetonitrile to toluene of 3:1 to 1:1. The selection of this mixed solvent is based on the solubility characteristics of the target product: acetonitrile has good solubility for lithium trifluoromethyl sulfinate, while toluene has good solubility for organic impurities in the system (such as unreacted sodium ascorbate degradation products, photocatalyst residues, etc.). Mixing the two in the above ratio allows the target product to precipitate rapidly during cooling, while impurities remain in the mother liquor, thereby effectively improving the crystallization purity of the target product. If the volume ratio is too large, the toluene content will be too low, resulting in poor impurity removal; if the volume ratio is too small, the acetonitrile content will be too low, leading to a decrease in the solubility of the target product and a reduction in yield.
[0017] The drying process is vacuum drying, with a drying temperature of 100~120℃ and a drying time of 10~14h. Vacuum drying can prevent oxygen and moisture in the air from coming into contact with the product, thus preventing the product from oxidizing or absorbing moisture. The drying temperature of 100~120℃ can completely remove residual solvents (acetonitrile, toluene, anhydrous ethanol, etc.) from the crystals, ensuring the purity of the product.
[0018] The molar ratio of sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate is 1.0:0.55~0.7:0.01~0.03:1.0~2.0. Lithium carbonate, as a lithium-ion donor, is used in an amount 0.55~0.7 times that of sodium sulfite. This ensures a sufficient supply of lithium ions to combine with trifluoromethylsulfinate anions to form lithium trifluoromethylsulfinate, while avoiding excessive lithium carbonate which could lead to an excessively high pH and side reactions. Tetrabutylammonium decatungstate, as a photocatalyst, is used in an amount 0.01~0.03 times that of sodium sulfite. This amount ensures that the photocatalyst fully absorbs photon energy, generates sufficient active species, and the catalytic reaction proceeds efficiently, while avoiding excessive use which could lead to catalyst residue. The residue is difficult to remove, increasing the difficulty of post-processing; if the dosage is too low, the catalytic activity is insufficient, the reaction rate is slow, and the yield is low; if the dosage is too high, the catalyst residue increases and the production cost increases; sodium ascorbate, as a reducing agent, can ensure the timely reduction of the active species after the photocatalyst is oxidized, so that it can be recycled and regenerated, while inhibiting the occurrence of oxidation side reactions in the system. If the dosage is too low, the reducing agent is insufficient, the photocatalyst cannot be effectively regenerated, the reaction rate decreases, and the by-products increase; if the dosage is too high, the excess sodium ascorbate will increase the difficulty of post-processing and increase the production cost.
[0019] This invention significantly reduces raw material costs by using trifluoromethane, a byproduct of fluorochemicals, as the trifluoromethyl source. This inexpensive industrial byproduct gas is directly converted into a high-value-added product, effectively reducing raw material costs compared to the expensive trifluoromethanesulfonyl chloride or sodium trifluoromethanesulfinate relied upon in existing technologies. The reaction steps are simplified, significantly improving atom economy. CS bond construction and lithiation can be completed in a single photocatalytic reaction, directly obtaining the target product. Compared to existing technologies involving multiple steps such as alkylation, hydrogenation reduction, and lithium salt substitution, the process flow is greatly simplified. The reaction conditions are mild and highly safe, proceeding at room temperature and driven by visible light, eliminating the need for high-temperature environments and highly corrosive raw materials. Unlike existing technologies that use highly reactive sulfonyl chloride reagents or require high-temperature hydrogenation reduction, this invention completely avoids the use of highly corrosive raw materials, has lower requirements for equipment materials, and effectively reduces equipment investment and safety maintenance costs. This invention is environmentally friendly, significantly reducing emissions of waste gas, wastewater, and solid waste. It employs a mixed solvent system, with water as the primary byproduct, and the photocatalyst is recyclable and reusable. Trifluoromethane has a much higher greenhouse effect potential than carbon dioxide, and currently, high-temperature incineration is the main disposal method, resulting in significant waste of fluorine resources and environmental pressure. This invention transforms it into a high-value-added product, achieving efficient resource utilization. Compared to existing technologies that generate large amounts of organic waste through multiple steps, this invention uses less organic solvent, employs a hydrogen atom transfer photocatalyst, has mild reaction conditions, fewer side reactions, and a simple reaction system. After recrystallization purification, the product has high purity and stable quality, with carbon emissions and environmental impact far lower than existing technologies. In summary, this invention has significant advantages in terms of raw material cost, reaction steps, reaction conditions, environmental friendliness, and product purity, providing an economical, efficient, green, and safe feasible technical path for the large-scale production and application of lithium trifluoromethyl sulfinate.
[0020] The molar ratio of the trifluoromethane gas to sodium sulfite is 1:1.0~2.0.
[0021] Applications of lithium trifluoromethyl sulfinate: Lithium trifluoromethyl sulfinate is used in lithium-ion battery replenishment, energy storage equipment, and the pharmaceutical and chemical industries. In lithium-ion battery replenishment, it is used as a replenishing agent for various types of lithium-ion batteries (including pouch batteries, cylindrical batteries, and prismatic batteries), particularly suitable for repairing degraded lithium-ion batteries and pre-replenishing new batteries. In energy storage equipment, it can be used as an electrolyte additive in energy storage batteries (such as sodium-ion batteries and lithium-sulfur batteries), with an addition amount of 0.1~3.0 wt% of the total electrolyte mass. Its function is to improve the ionic conductivity and stability of the electrolyte, inhibit the dissolution of electrode materials and side reactions, extend the cycle life and service time of the energy storage battery, and simultaneously reduce the internal resistance of the energy storage battery, thereby improving energy storage efficiency. Furthermore, lithium trifluoromethyl sulfinate can be used as a fluorine-containing reagent in the synthesis of pharmaceutical intermediates, especially suitable for the preparation of drug molecules containing trifluoromethyl groups.
[0022] Compared with the prior art, the beneficial effects of the present invention are:
[0023] (1) The lithium trifluoromethyl sulfinate prepared by the present invention has better overall performance, higher purity and higher yield than existing products; fewer impurities, strong electrochemical stability, good solubility and good compatibility with various materials. It can meet the needs of high-end fields such as new energy and pharmaceutical chemical industry without further purification, and effectively solves the technical defects of insufficient purity and unstable performance of existing products.
[0024] (2) The preparation method of the present invention significantly reduces costs by replacing expensive prefunctionalized high-activity fluorine-containing reagents with inexpensive and readily available trifluoromethane, eliminating the need for complex raw material pretreatment and making it more suitable for large-scale production; the process is simplified and highly efficient, and preparation can be completed in one step of light irradiation reaction without the need for multiple steps of reaction and multiple separation and purification, the reaction conditions are mild, the operation is simple and energy consumption is low; it is environmentally friendly, the reaction produces no toxic or harmful byproducts, the post-treatment waste liquid is small in volume and simple in composition, and is easy to treat, while the reaction system is stable and controllable, and the product quality is uniform.
[0025] (3) The lithium trifluoromethyl sulfinate of the present invention has better application effects and a wider range of applications. In the field of lithium-ion battery replenishment, it can restore the first discharge capacity of a battery whose capacity has decayed to 80% of its initial capacity to more than 99% of its initial value, and the capacity retention rate is still more than 87% after 1000 cycles, with significant lithium replenishment effect; in the field of energy storage equipment, it can improve the stability and ionic conductivity of electrolyte, extend the cycle life of equipment, and improve energy storage efficiency; in the field of pharmaceutical and chemical industry, it can be used as a stable trifluoromethyl source for the synthesis of drug intermediates, with high reaction selectivity and few by-products, which can effectively improve drug performance and meet the synthesis needs of various fluorine-containing drugs, with application value significantly higher than existing products. Attached Figure Description
[0026] Figure 1 Lithium trifluoromethyl sulfinate, the product prepared in Example 1 19 F nuclear magnetic resonance spectrum. Detailed Implementation
[0027] The present invention will be further described below with reference to specific embodiments.
[0028] Example 1
[0029] The preparation method of lithium trifluoromethyl sulfinate according to the present invention includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (7.56 g, 0.06 mol), lithium carbonate (2.44 g, 0.033 mol), tetrabutylammonium decatungstate (3.98 g, 0.0012 mol), and sodium ascorbate (11.88 g, 0.060 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 4:1 (128 mL acetonitrile + 32 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.8 MPa. Stirring is started, and the reactor is irradiated with a 407 nm visible light LED light source and reacted at room temperature for 10 h. The reaction solution is concentrated to a viscous state by rotary evaporation, and the product is dissolved in 100 mL of anhydrous ethanol. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 3:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 100°C for 12 h to obtain 6.6 g of lithium trifluoromethyl sulfinate, with a yield of 94.3% and a purity of 99.9%.
[0030] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 99.5% of its initial value, and after 1000 cycles, the capacity retention rate still reached 87.7%. 19 F nuclear magnetic resonance spectrum as shown Figure 1 As shown.
[0031] Example 2
[0032] The preparation method of lithium trifluoromethyl sulfinate according to the present invention includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (6.3 g, 0.050 mol), lithium carbonate (2.59 g, 0.035 mol), tetrabutylammonium decatungstate (4.98 g, 0.0015 mol), and sodium ascorbate (14.85 g, 0.075 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 2:1 (120 mL acetonitrile + 40 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.6 MPa. Stirring is started, and the reactor is irradiated with a 430 nm visible light LED light source and reacted at room temperature for 6 hours. The reaction solution is concentrated to a viscous state by rotary evaporation, and 100 mL of anhydrous ethanol is added to dissolve the product. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 2:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 120°C for 12 h to obtain 6.31 g of lithium trifluoromethyl sulfinate, with a yield of 90.1% and a purity of 99.7%.
[0033] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 99.2% of its initial value, and after 1000 cycles, the capacity retention rate still reached 87.2%.
[0034] Example 3
[0035] The preparation method of lithium trifluoromethyl sulfinate according to the present invention includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (12.6 g, 0.100 mol), lithium carbonate (4.43 g, 0.060 mol), tetrabutylammonium decatungstate (6.64 g, 0.0020 mol), and sodium ascorbate (19.81 g, 0.100 mol) are added sequentially and dissolved in a 1:1 volume ratio of acetonitrile and water (80 mL acetonitrile + 80 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.4 MPa. Stirring is started, and the reactor is irradiated with a 420 nm visible light LED light source and reacted at room temperature for 12 h. The reaction solution is concentrated to a viscous state by rotary evaporation, and 100 mL of anhydrous ethanol is added to dissolve the product. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 1:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 100°C for 12 h to obtain 6.53 g of lithium trifluoromethyl sulfinate, with a yield of 93.3% and a purity of 99.8%.
[0036] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 99.3% of its initial value, and after 1000 cycles, the capacity retention rate still reached 87.4%.
[0037] Example 4
[0038] The preparation method of lithium trifluoromethyl sulfinate according to the present invention includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (9.45 g, 0.075 mol), lithium carbonate (3.84 g, 0.052 mol), tetrabutylammonium decatungstate (2.49 g, 0.00075 mol), and sodium ascorbate (29.72 g, 0.150 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 4:1 (128 mL acetonitrile + 32 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 1.0 MPa. Stirring is started, and the reactor is irradiated with a 400 nm visible light LED light source and reacted at room temperature for 8 hours. The reaction solution is concentrated to a viscous state by rotary evaporation, and 100 mL of anhydrous ethanol is added to dissolve the product. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 1:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 110℃ for 12 h to obtain 6.39 g of lithium trifluoromethyl sulfinate, with a yield of 91.3% and a purity of 99.8%.
[0039] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 99.4% of its initial value, and after 1000 cycles, the capacity retention rate still reached 87.2%.
[0040] Comparative Example 1
[0041] The preparation method of lithium trifluoromethyl sulfinate described in this comparative example includes the following steps: In a 500 mL high-pressure photoreactor, anhydrous sodium sulfate (8.52 g, 0.06 mol), lithium carbonate (2.44 g, 0.033 mol), tetrabutylammonium decatungstate (3.98 g, 0.0012 mol), and sodium ascorbate (11.88 g, 0.060 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 4:1 (128 mL acetonitrile + 32 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.8 MPa. Stirring is started, and the reactor is irradiated with a 407 nm visible light LED light source and reacted at room temperature for 10 h. The reaction solution is concentrated to a viscous state by rotary evaporation, and 100 mL of anhydrous ethanol is added to dissolve the product. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 3:1 was added for recrystallization. Upon cooling, white crystals precipitated. The crystals were collected by filtration and dried under vacuum at 100°C for 12 hours, yielding approximately 0.2 g of a white solid. Lithium trifluoromethyl sulfinate was not detected, making lithium supplementation impossible.
[0042] Comparative Example 2
[0043] The preparation method of lithium trifluoromethyl sulfinate described in this comparative example includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (7.56 g, 0.06 mol), lithium hydroxide (0.79 g, 0.033 mol), tetrabutylammonium decatungstate (3.98 g, 0.0012 mol), and sodium ascorbate (11.88 g, 0.060 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 4:1 (128 mL acetonitrile + 32 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.8 MPa. Stirring is started, and the reactor is irradiated with a 407 nm visible light LED light source and reacted at room temperature for 10 h. The reaction solution is concentrated to a viscous state by rotary evaporation, and the product is dissolved in 100 mL of anhydrous ethanol. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 3:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 100℃ for 12 h to obtain 5.51 g of lithium trifluoromethyl sulfinate, with a yield of 55.6% and a purity of 82.1%. The reaction solution was dark in color and contained byproducts.
[0044] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 75.2% of the initial value, and after 1000 cycles, the capacity retention rate still reached 55.8%.
[0045] Comparative Example 3
[0046] The preparation method of lithium trifluoromethyl sulfinate described in this comparative example includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (7.56 g, 0.06 mol), lithium carbonate (2.44 g, 0.033 mol), eosin Y (0.78 g, 0.0012 mol), and sodium ascorbate (11.88 g, 0.060 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 4:1 (128 mL acetonitrile + 32 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.8 MPa. Stirring is started, and the reactor is irradiated with a 407 nm visible light LED light source and reacted at room temperature for 10 h. The reaction solution is concentrated to a viscous state by rotary evaporation, and the product is dissolved in 100 mL of anhydrous ethanol. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 3:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 100°C for 12 hours to obtain 1.3 g of lithium trifluoromethyl sulfinate, with a yield of 18.6% and a purity of 86.3%.
[0047] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 79.5% of the initial value, and after 1000 cycles, the capacity retention rate still reached 60.3%.
[0048] Comparative Example 4
[0049] The preparation method of lithium trifluoromethyl sulfinate described in this comparative example includes the following steps: In a 500 mL high-pressure photoreactor, sodium sulfite (7.56 g, 0.06 mol), lithium carbonate (2.44 g, 0.033 mol), tetrabutylammonium decatungstate (3.98 g, 0.0012 mol), and triethylamine (6.07 g, 0.060 mol) are added sequentially and dissolved in a mixed solvent of acetonitrile and water at a volume ratio of 4:1 (128 mL acetonitrile + 32 mL water). The reactor is sealed, purged three times with high-purity nitrogen, and then trifluoromethane gas (0.05 mol) is introduced into the reactor, followed by high-purity nitrogen, until the total pressure inside the reactor reaches 0.8 MPa. Stirring is started, and the reactor is irradiated with a 407 nm visible light LED light source and reacted at room temperature for 10 h. The reaction solution is concentrated to a viscous state by rotary evaporation, and the product is dissolved in 100 mL of anhydrous ethanol. The insoluble inorganic salts are removed by filtration. After the filtrate was concentrated again, a mixed solvent of acetonitrile and toluene in a volume ratio of 3:1 was added for recrystallization, and white crystals precipitated upon cooling. The crystals were collected by filtration and dried under vacuum at 100°C for 12 hours to obtain 4.11 g of lithium trifluoromethyl sulfinate, with a yield of 58.7% and a purity of 92.7%.
[0050] Application: The prepared lithium trifluoromethyl sulfinate was dissolved in a lithium-ion battery electrolyte (composition: 1.0 M LiPF6, EC / EMC volume ratio 3:7, containing 2.0% VC), with an addition amount of 2.0 wt% of the total mass of the electrolyte. Graphite / LiFePO4 pouch cells with capacity decayed to 80% of their initial capacity were selected. In an argon-filled glove box, the lithium-replenishing electrolyte was injected through the injection port, sealed, and allowed to stand for 12 hours. The first charge was performed at a constant current of 0.1C to 4.3V to allow for complete decomposition of the lithium replenishing agent. Subsequently, the edge of the gas bag was cut open in the argon-filled glove box to evacuate the battery and remove the gas generated by the decomposition of the lithium replenishing agent, followed by resealing. After venting, charge-discharge cycle tests were conducted at a 1C rate. The results showed that after lithium replenishment, the battery's first discharge capacity recovered to 91.3% of the initial value, and after 1000 cycles, the capacity retention rate still reached 74.5%.
Claims
1. A method for preparing lithium trifluoromethyl sulfinate, characterized in that, Includes the following steps: First, sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate are mixed and dissolved in a solvent, namely acetonitrile and water, with a volume ratio of acetonitrile to water of 4:1 to 1:
1. The resulting system is deoxygenated, and then trifluoromethane gas is introduced, with the reaction pressure controlled at 0.4 to 1.0 MPa. A visible light source is turned on, with the wavelength controlled at 400 to 430 nm, and the reaction is irradiated to obtain a reaction solution. Finally, the reaction solution is post-treated to obtain lithium trifluoromethyl sulfinate.
2. The method for preparing lithium trifluoromethyl sulfinate according to claim 1, characterized in that: The light-induced reaction proceeds at room temperature for 6-12 hours.
3. The method for preparing lithium trifluoromethyl sulfinate according to claim 1, characterized in that: The specific post-processing steps are as follows: evaporate and concentrate the reaction solution to a viscous state, add anhydrous ethanol to dissolve it, filter, concentrate the filtrate again, add mixed solvent to recrystallize, cool and precipitate white crystals, filter and collect the white crystals, and dry.
4. The method for preparing lithium trifluoromethyl sulfinate according to claim 3, characterized in that: The mixed solvent is acetonitrile and toluene, with a volume ratio of acetonitrile to toluene of 3:1 to 1:
1.
5. The method for preparing lithium trifluoromethyl sulfinate according to claim 3, characterized in that: The drying process is vacuum drying, and the drying temperature is 100~120℃.
6. The method for preparing lithium trifluoromethyl sulfinate according to claim 1, characterized in that: The molar ratio of sodium sulfite, lithium carbonate, tetrabutylammonium decatungstate, and sodium ascorbate is 1.0:0.55~0.7:0.01~0.03:1.0~2.
0.
7. The method for preparing lithium trifluoromethyl sulfinate according to claim 1, characterized in that: The molar ratio of the trifluoromethane gas to sodium sulfite is 1:1.0~2.
0.
8. The method for preparing lithium trifluoromethyl sulfinate according to claim 1, characterized in that: The prepared lithium trifluoromethyl sulfinate is used in lithium-ion battery lithium replenishment, energy storage equipment, or pharmaceutical and chemical fields.