Device for the continuous preparation of lithium difluorooxalato borate
By using a dynamic microchannel reactor and a separation device in combination, the problems of low solid-liquid reaction efficiency and chloride metathesis in the preparation of lithium difluorooxalate borate were solved, realizing efficient and continuous production and the preparation of high-purity products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- JIUJIANG TINCI ADVANCED MATERIALS CO LTD
- Filing Date
- 2025-08-05
- Publication Date
- 2026-07-21
Smart Images
Figure CN224524724U_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of electrolyte salt synthesis technology, specifically relating to an apparatus for the continuous preparation of lithium difluorooxalate borate. Background Technology
[0002] Lithium difluorooxalate borate (LiODFB) is an important high-performance electrolyte additive for lithium-ion batteries, combining the advantages of both lithium difluorooxalate borate and lithium tetrafluoroborate. It possesses excellent electrochemical properties and thermal stability, facilitating the formation of a more stable SEI film on the negative electrode surface, thereby improving the battery's high-temperature cycle performance and high-temperature storage performance. Furthermore, the SEI film formed by LiODFB can prevent the co-intercalation of electrolyte solvents (especially propylene carbonate) on the negative electrode surface, preventing damage to the SEI film structure.
[0003] Currently, some technologies propose a synthetic route that uses oxalates, such as sodium oxalate, to react with chlorosilanes to obtain oxalate silica esters, followed by the reaction of the silica esters with lithium tetrafluoroborate to obtain lithium difluorooxalate borate. This route generally consists of two steps: first, the oxalate reacts with chlorosilanes to generate oxalate silica esters; second, the silica esters react with lithium tetrafluoroborate to generate lithium difluorooxalate borate. Existing apparatus for preparing lithium difluorooxalate borate suffers from low solid-liquid reaction efficiency due to the presence of both solids (such as oxalates, chlorides, and lithium tetrafluoroborate) and liquids in the two-step reaction. Furthermore, the generated chlorides, such as sodium chloride, undergo a metathesis reaction with the lithium tetrafluoroborate from the second step, resulting in high acidity and excessive chloride ion content in the reaction products. Utility Model Content
[0004] This application aims to at least partially address one of the technical problems in the related art. Therefore, one objective of this application is to provide an apparatus for the continuous preparation of lithium difluorooxalate borate. The apparatus for the continuous preparation of lithium difluorooxalate borate proposed in this application improves production efficiency and yields high-quality lithium difluorooxalate borate.
[0005] The first aspect of this application discloses an apparatus for the continuous preparation of lithium difluorooxalate borate, comprising a first dynamic microchannel reactor, a second dynamic microchannel reactor, and a separation device. The first dynamic microchannel reactor provides space for the reaction of oxalate and chlorosilane. The second dynamic microchannel reactor is located downstream of the first dynamic microchannel reactor and receives the reaction products from the first dynamic microchannel reactor, while also providing space for the reaction of the reaction products from the first dynamic microchannel reactor with lithium tetrafluoroborate. The separation device is located downstream of the second dynamic microchannel reactor and separates the reaction products from the second dynamic microchannel reactor to obtain lithium difluorooxalate borate.
[0006] The apparatus for continuous preparation of lithium difluorooxalate borate according to embodiments of this application employs a combination of a first dynamic microchannel reactor and a second dynamic microchannel reactor. This fully utilizes the tolerance of the dynamic microchannel reactor to solid substances, and both reactors offer high heat and mass transfer efficiency, high safety, and high reaction efficiency. By combining the two processes with the reaction equipment, the solid-containing reaction liquid obtained from the first step reaction in the first dynamic microchannel reactor can directly enter the second dynamic microchannel reactor for the second step reaction without separating chloride salts such as sodium chloride. Separation is performed uniformly after the reaction, minimizing the probability of chloride salts undergoing metathesis reactions, thus ensuring the quality of the obtained lithium difluorooxalate borate. In summary, the apparatus for continuous preparation of lithium difluorooxalate borate proposed in this application enables continuous production of lithium difluorooxalate borate, improves production efficiency, and yields high-quality lithium difluorooxalate borate with low impurity content.
[0007] In some embodiments of this application, the separation device includes a flash tank located downstream of the second dynamic microchannel reactor for removing volatile gases from the reaction products in the second dynamic microchannel reactor. This enables continuous production of lithium difluorooxalate borate, improving production efficiency, and yields high-quality lithium difluorooxalate borate with low impurity content.
[0008] In some embodiments of this application, the separation device further includes a continuous centrifuge located downstream of the flash tank. The continuous centrifuge receives the solid-liquid mixture flowing out of the flash tank and separates and removes the solid to obtain a lithium difluorooxalate borate solution. This enables continuous production of lithium difluorooxalate borate, improving production efficiency, and yields high-quality lithium difluorooxalate borate with low impurity content.
[0009] In some embodiments of this application, the apparatus for the continuous preparation of lithium difluorooxalate borate further includes a back pressure system. The back pressure system is connected to at least one of the flash tank, the continuous centrifuge, the first dynamic microchannel reactor, and the second dynamic microchannel reactor, and is used to increase the internal pressure of at least one of the flash tank, the continuous centrifuge, the first dynamic microchannel reactor, and the second dynamic microchannel reactor. This enables continuous production of lithium difluorooxalate borate, improves production efficiency, and yields high-quality lithium difluorooxalate borate with low impurity content.
[0010] In some embodiments of this application, the apparatus for continuous preparation of lithium difluorooxalate borate further includes a chlorosilane storage tank, which is located upstream of the first dynamic microchannel reactor. A first feed pump is provided between the chlorosilane storage tank and the first dynamic microchannel reactor to transport the chlorosilane in the chlorosilane storage tank to the first dynamic microchannel reactor.
[0011] In some embodiments of this application, the apparatus for continuous preparation of lithium difluorooxalate borate further includes an oxalate storage tank located upstream of the first dynamic microchannel reactor. The oxalate storage tank is used to store oxalate solution. A second feed pump is provided between the oxalate storage tank and the first dynamic microchannel reactor to deliver the oxalate solution to the first dynamic microchannel reactor.
[0012] In some embodiments of this application, the apparatus for continuous preparation of lithium difluorooxalate borate further includes a lithium tetrafluoroborate storage tank, which is located upstream of the second dynamic microchannel reactor. The lithium tetrafluoroborate storage tank is used to store a lithium tetrafluoroborate solution. A third feed pump is provided between the lithium tetrafluoroborate storage tank and the second dynamic microchannel reactor to deliver the lithium tetrafluoroborate solution to the second dynamic microchannel reactor. This enables continuous production of lithium difluorooxalate borate, improves production efficiency, and produces high-quality lithium difluorooxalate borate with low impurity content.
[0013] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0014] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:
[0015] Figure 1 This is a structural diagram of an apparatus for the continuous preparation of lithium difluorooxalate borate according to an embodiment of this application.
[0016] Figure 2 This is a chromatogram of a solution of lithium difluorooxalate borate and an ester solvent obtained by the apparatus obtained according to the method of Example 1 of this application.
[0017] Explanation of icon numbers:
[0018] 1. Chlorosilane storage tank; 2. Oxalate storage tank; 3. First feed pump; 4. Second feed pump; 5. First dynamic microchannel reactor; 6. Lithium tetrafluoroborate storage tank; 7. Third feed pump; 8. Second dynamic microchannel reactor; 9. Flash tank; 10. Continuous centrifuge; 11. First agitator; 12. Second agitator. Detailed Implementation
[0019] The embodiments of this application are described in detail below. The embodiments described below are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0020] Lithium difluorooxalate borate is an important high-performance electrolyte additive for lithium-ion batteries, combining the advantages of both lithium difluorooxalate borate and lithium tetrafluoroborate, and possessing excellent electrochemical properties and thermal stability.
[0021] Existing methods for preparing lithium difluorooxalate borate mainly involve synthesizing lithium tetrafluoroborate from lithium oxalate and boron trifluoride, followed by reacting lithium tetrafluoroborate with oxalic acid to obtain lithium difluorooxalate borate. This method involves corrosive materials such as boron trifluoride and oxalic acid, placing high demands on the reaction system and increasing equipment costs and maintenance complexity. Furthermore, this reaction route involves gas-liquid reactions, resulting in low reaction efficiency and producing large amounts of corrosive exhaust gas, making continuous production difficult.
[0022] Existing apparatuses for preparing lithium difluorooxalate borate have low solid-liquid reaction efficiency due to the presence of solids (such as oxalates, chlorides, lithium tetrafluoroborate, etc.) and liquids in the two-step reaction. Furthermore, the generated chlorides, such as sodium chloride, undergo metathesis reactions with the lithium tetrafluoroborate in the second step, resulting in high acidity and excessive chloride ion content in the reaction products.
[0023] In view of this, the first aspect of this application proposes an apparatus for the continuous preparation of lithium difluorooxalate borate. For embodiments of this application, please refer to... Figure 1 The aforementioned continuous preparation apparatus for lithium difluorooxalate borate includes a first dynamic microchannel reactor 5, a second dynamic microchannel reactor 8, and a separation device. The first dynamic microchannel reactor 5 provides space for the reaction of oxalate and chlorosilane. The second dynamic microchannel reactor 8 is located downstream of and connected to the first dynamic microchannel reactor 5, and is used to receive the reaction products from the first dynamic microchannel reactor 5, and to provide space for the reaction of the reaction products from the first dynamic microchannel reactor 5 with lithium tetrafluoroborate. The separation device is located downstream of and connected to the second dynamic microchannel reactor 8, and is used to separate the reaction products from the second dynamic microchannel reactor 8 to obtain lithium difluorooxalate borate.
[0024] The following is a detailed description of the beneficial effects that the apparatus for the continuous preparation of lithium difluorooxalate borate proposed in this application can achieve:
[0025] This application provides an apparatus for the continuous preparation of lithium difluorooxalate borate, employing a first dynamic microchannel reactor 5 and a second dynamic microchannel reactor 8 in combination. This fully utilizes the tolerance of dynamic microchannel reactors to solid substances, and both reactors offer high heat and mass transfer efficiency, high safety, and high reaction efficiency. By combining the two processes with the reaction equipment, the solid-containing reaction liquid obtained from the first step reaction in the first dynamic microchannel reactor 5 can directly enter the second dynamic microchannel reactor 8 for the second step reaction without separating chloride salts such as sodium chloride. Separation is then performed uniformly after the reaction, minimizing the probability of chloride salts undergoing metathesis reactions and ensuring the quality of the obtained lithium difluorooxalate borate. In summary, the apparatus for the continuous preparation of lithium difluorooxalate borate proposed in this application enables continuous production of lithium difluorooxalate borate, improves production efficiency, and yields high-quality lithium difluorooxalate borate with low impurity content.
[0026] It is understandable that for reactions containing solids (such as oxalates, chlorides, lithium tetrafluoroborate, etc.), conventional microreactors or pipeline reactors are prone to solid blockage. Therefore, this application adopts a dynamic microchannel reactor (first dynamic microchannel reactor 5 and second dynamic microchannel reactor 8), which combines an outer jacket with an internal stirrer. The built-in stirring shaft rotates at high speed and also has a heat exchange function, making it an option for continuous solid-liquid reactions and less prone to solid blockage.
[0027] The advantages of the apparatus for the continuous preparation of lithium difluorooxalate borate proposed in this application are detailed below:
[0028] High heat and mass transfer efficiency: The first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8 can achieve efficient temperature control in the reaction chamber. Under the high-speed rotation of the stirring paddle, the liquid and solid are kept moving in one direction, reducing back mixing and ensuring the average residence time of the reaction. When lithium tetrafluoroborate solution is added during the series connection of the two dynamic microchannel reactors, the two phases of liquid are mixed in seconds in the dynamic microchannel reactor. The materials react rapidly according to the molar ratio, resulting in high selectivity for the synthesis of lithium difluorooxalate borate and fewer metathesis reactions.
[0029] High safety: The first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8 have low liquid holding capacity and can withstand solid-liquid reaction conditions. Internal stirring can be installed inside the first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8. The internal stirring can include a stirring shaft and blades. After the reaction starts, the blades can force the solid to move, eliminating the risk of overpressure caused by solid blockage. The stirring shaft can be hollow, with an inlet and outlet for the heat exchange medium connected to the inside of the stirring shaft, facilitating the introduction of the heat exchange medium for heating or cooling. Heat exchange medium is present both inside and outside the stirring shaft of the first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8, ensuring accurate material temperature control. Rapid material flow during stirring avoids localized overheating or hot spots.
[0030] Specifically, an external heating jacket can be provided on the outer surface of the first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8. The heating jacket has an inlet and an outlet for the heat exchange medium to facilitate the introduction of the heat exchange medium and control the internal temperature of the first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8.
[0031] High reaction efficiency: The reaction raw materials use ester solvents, and after solid-liquid separation after the reaction, a solution of lithium difluorooxalate borate dissolved in ester solvent is directly produced, which is compatible with the electrolyte solvent. No additional preparation process is required, resulting in high production efficiency. The reaction time is short when synthesizing lithium difluorooxalate borate, and the metathesis reaction between chloride salts such as sodium chloride and lithium tetrafluoroborate occurs less.
[0032] High product purity: The inorganic byproducts such as lithium chloride and ammonium tetrafluoroborate produced by the reaction of chloride salts such as sodium chloride with lithium tetrafluoroborate have low solubility in ester solvents. After simple drying of the moist solid, industrial-grade byproduct sodium chloride is obtained. However, the product lithium difluorooxalate borate has high solubility in ester solvents. Therefore, during solid-liquid separation, impurities enter the sodium chloride solution and are treated as industrial-grade sodium chloride. The insoluble matter, chloride ions, and acidity of lithium difluorooxalate borate in the ester solvent solution are controllable.
[0033] Furthermore, this application enables the optimization of reaction conditions, further improving the purity and yield of the product. The reaction process involves fewer steps, and the chloride ion content and acidity of the lithium difluorooxalate borate liquid salt product are controllable, ensuring consistent quality.
[0034] Specifically, taking sodium oxalate as an example, the reaction equation in the first dynamic microchannel reactor 5 is as follows:
[0035] Na2C2O4+2Si(CH3)3Cl→(Si(CH3)3)2C2O4+2NaCl.
[0036] The reaction equation in the second dynamic microchannel reactor 8 is:
[0037] (Si(CH3)3)2C2O4+LiBF4→LiC2O4BF2+2Si(CH3)3F.
[0038] According to some specific embodiments of this application, the separation device is a device for separating lithium difluorooxalate borate generated in the second dynamic microchannel reactor 8. The separation device may include one or both of a gas-liquid separation device and a solid-liquid separation device. The gas-liquid separation device separates volatile gases such as solvents from the product solution. As an example, the gas-liquid separation device may be a flash separator. The solid-liquid separation device separates solids (such as oxalate, chloride, lithium tetrafluoroborate, etc.) from the product solution. The solid-liquid separation device may be a centrifuge.
[0039] According to some specific embodiments of this application, please refer to Figure 1 The separation device includes a flash tank 9, which is located downstream of and connected to the second dynamic microchannel reactor 8. The flash tank 9 is used to remove volatile gases from the reaction products in the second dynamic microchannel reactor 8. The flash tank 9 is a separation device that rapidly vaporizes (flashes) the liquid when the pressure suddenly decreases. After the reaction, the material continuously enters the flash tank 9. When the pressure in the flash tank 9 suddenly decreases, a mixture of gases including fluorosilanes, chlorosilanes, and solvent vapors is discharged from the gas phase, which can further reduce the impurity content in the obtained lithium difluorooxalate borate.
[0040] According to some specific embodiments of this application, please refer to Figure 1 The separation device further includes a continuous centrifuge 10, which is located downstream of the flash tank 9 and connected to it. The continuous centrifuge 10 receives the solid-liquid mixture flowing out of the flash tank 9 and separates and removes the solid to obtain a lithium difluorooxalate borate solution. The continuous centrifuge 10 is a highly automated solid-liquid separation device with full-speed operation, continuous feeding and discharging. After the reaction, the material continuously enters the flash tank 9. A mixture of gases, including fluorosilanes, chlorosilanes, and solvent evaporation gases, is discharged from the gas phase, while the liquid enters the continuous centrifuge 10. The continuous centrifuge 10 separates the solid chloride salt and the liquid, forming a 15% moisture content chloride salt, such as sodium chloride solid, and the product lithium difluorooxalate borate solution (the solvent can be an ester solvent). The 15% moisture content chloride salt solid is dried to obtain a chloride salt byproduct.
[0041] The apparatus for the continuous preparation of lithium difluorooxalate borate further includes a back pressure system. This back pressure system is connected to at least one of the flash tank 9, the continuous centrifuge 10, the first dynamic microchannel reactor 5, and the second dynamic microchannel reactor 8. It is used to increase the internal pressure of at least one of these components. The back pressure system refers to an artificially created or naturally existing reverse pressure in a fluid or steam system, used to increase and stabilize the internal pressure of at least one of these components. For example, the back pressure system can be a self-regulating back pressure valve. This facilitates improved reaction efficiency and results in high-quality lithium difluorooxalate borate with low impurity content.
[0042] It is understandable that when the back pressure system is connected to a component, it can increase the pressure inside that component and keep it stable. For example, the pressure of the corresponding component can be controlled between 0.5 MPa and 1 MPa. For instance, when the back pressure system is connected to the flash tank 9 and the continuous centrifuge 10 respectively, the pressure inside the flash tank 9 and the continuous centrifuge 10 can be controlled between 0.5 MPa and 1 MPa.
[0043] According to some specific embodiments of this application, the temperature of the flash tank 9 is 110℃~120℃, for example, it can be 110℃, 112℃, 115℃, 117℃, 120℃, etc. Controlling the temperature of the flash tank 9 within the above range allows the mixed gas of fluorosilanes, chlorosilanes and solvent volatilization gases in the product of the second dynamic microchannel reactor 8 to be discharged from the gas phase, thereby achieving the separation of impurities and facilitating the removal of fluorosilanes, chlorosilanes, etc. from the reaction products, resulting in high quality and low impurity content of the prepared lithium difluorooxalate borate.
[0044] According to some specific embodiments of this application, the pressure of the flash tank 9 is 0.5MPa to 1MPa, for example, it can be 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1MPa, etc., thereby facilitating the production of high-quality lithium difluorooxalate borate with low impurity content.
[0045] According to some specific embodiments of this application, the rotational speed of the continuous centrifuge 10 is 60 r / min to 120 r / min. For example, it can be 60 r / min, 80 r / min, 100 r / min, 120 r / min, etc. Controlling the rotational speed of the continuous centrifuge 10 within the above range can ensure the separation of solid chloride salts such as sodium chloride from lithium difluorooxalate borate solution, and can also keep the moisture content of the solid chloride salts below 15%, which is convenient for subsequent drying.
[0046] According to some specific embodiments of this application, the pressure of the continuous centrifuge 10 is 0.5MPa to 1MPa, for example, it can be 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1MPa, etc., thereby facilitating the production of high-quality lithium difluorooxalate borate with low impurity content.
[0047] According to some specific embodiments of this application, please refer to Figure 1 The apparatus for continuous production of lithium difluorooxalate borate further includes a chlorosilane storage tank 1, which is located upstream of the first dynamic microchannel reactor 5. A first feed pump 3 is provided between the chlorosilane storage tank 1 and the first dynamic microchannel reactor 5. The chlorosilane storage tank 1 and the first dynamic microchannel reactor 5 are respectively connected to the first feed pump 3, so that the first feed pump 3 delivers the chlorosilane in the chlorosilane storage tank 1 to the first dynamic microchannel reactor 5. The first feed pump 3 can also adjust the flow rate of the chlorosilane as needed, serving as a metering pump. Therefore, continuous production of lithium difluorooxalate borate can be achieved, improving production efficiency, and the obtained lithium difluorooxalate borate has high quality and low impurity content.
[0048] According to some specific embodiments of this application, please refer to Figure 1 The apparatus for continuous production of lithium difluorooxalate borate further includes an oxalate storage tank 2, which is located upstream of the first dynamic microchannel reactor 5. The oxalate storage tank 2 stores oxalate solution. A second feed pump 4 is connected between the oxalate storage tank 2 and the first dynamic microchannel reactor 5, allowing the second feed pump 4 to deliver the oxalate solution to the first dynamic microchannel reactor 5. The second feed pump 4 can also adjust the flow rate of the oxalate solution as needed, serving as a metering pump. This enables continuous production of lithium difluorooxalate borate, improving production efficiency, and producing high-quality lithium difluorooxalate borate with low impurity content.
[0049] According to some embodiments of this application, the oxalate storage tank 2 is provided with a first stirring paddle 11, which rotates at high speed in the oxalate storage tank 2 to make the oxalate solution uniform and stable, thereby reducing oxalate precipitation.
[0050] According to some specific embodiments of this application, please refer to Figure 1The apparatus for continuous preparation of lithium difluorooxalate borate further includes a lithium tetrafluoroborate storage tank 6, which is located upstream of the second dynamic microchannel reactor 8. The lithium tetrafluoroborate storage tank 6 is used to store lithium tetrafluoroborate solution. A third feed pump 7 is provided between the lithium tetrafluoroborate storage tank 6 and the second dynamic microchannel reactor 8. The lithium tetrafluoroborate storage tank 6 and the second dynamic microchannel reactor 8 are respectively connected to the third feed pump 7, so that the third feed pump 7 delivers the lithium tetrafluoroborate solution to the second dynamic microchannel reactor 8. The third feed pump 7 can also adjust the flow rate of the lithium tetrafluoroborate solution as needed, serving as a metering pump. Therefore, continuous production of lithium difluorooxalate borate can be achieved, improving production efficiency, and the obtained lithium difluorooxalate borate has high quality and low impurity content.
[0051] According to some specific embodiments of this application, the lithium tetrafluoroborate storage tank 6 is provided with a second stirring paddle 12, which rotates at high speed in the lithium tetrafluoroborate storage tank 6, making the lithium tetrafluoroborate solution uniform and stable, and reducing the precipitation of lithium tetrafluoroborate.
[0052] According to some specific embodiments of this application, the pressure of the apparatus for the continuous preparation of lithium difluorooxalate borate is 0.5 MPa to 1 MPa. As an example, the pressure of the apparatus for the continuous preparation of lithium difluorooxalate borate can be 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa, 0.9 MPa, 1 MPa, etc. Specifically, nitrogen can be used to increase the pressure of the entire apparatus to 0.5 MPa to 1 MPa, and the pressure of the entire apparatus can be stabilized by a back pressure system. This ensures that the reaction process in the two dynamic microchannel reactors is carried out under high pressure, promoting complete reaction in the first dynamic microchannel reactor 5 and the second dynamic microchannel reactor 8, thereby improving reaction efficiency and product purity, and enhancing the stability of the entire apparatus for the continuous preparation of lithium difluorooxalate borate.
[0053] According to some specific embodiments of this application, the reaction temperature of the first dynamic microchannel reactor 5 is 50℃ to 120℃, for example, it can be 50℃, 70℃, 90℃, 100℃, 120℃, etc. Controlling the reaction temperature of the first dynamic microchannel reactor 5 within the above range, the higher reaction temperature can promote the rapid reaction of oxalates such as sodium oxalate with chlorosilanes, shorten the reaction time, and match the fast reaction of the second dynamic microchannel reactor, realizing the continuous production of lithium difluorooxalate borate, improving production efficiency, and producing high-quality lithium difluorooxalate borate.
[0054] According to some specific embodiments of this application, the reaction temperature of the second dynamic microchannel reactor 8 is 20℃~70℃. For example, it can be 20℃, 40℃, 50℃, 70℃, etc. Controlling the reaction temperature of the second dynamic microchannel reactor 8 within the above range has little impact on the main reaction rate. However, the metathesis reaction rate of chloride salts such as sodium chloride is extremely slow, and the product selectivity is higher than 99%, which is beneficial to improving the quality of lithium difluorooxalate borate and reducing the impurity content. At the same time, it can reduce the formation process of fluorosilanes, reduce the generation of bubbles, and thus reduce the impact on the average residence time of materials, ensuring the efficient progress of the reaction.
[0055] According to some specific embodiments of this application, the oxalate solution contains oxalate by mass of less than or equal to 20%. For example, the mass percentage of oxalate may be 1%, 5%, 10%, 15%, 20%, etc. Controlling the mass percentage of oxalate within the above range can ensure the full progress of the reaction and avoid the formation of byproducts.
[0056] According to some specific embodiments of this application, the mass flow rate ratio of the oxalate solution to the chlorosilane is (4-10):1, for example, it can be 4:1, 5:1, 7:1, 9:1, 10:1, etc. By controlling the mass flow rate ratio of the oxalate solution to the chlorosilane within the above range, the molar ratio of oxalate (such as sodium oxalate) to chlorosilane can be 1:(1.01-1.05), which promotes the complete reaction of sodium oxalate after the reaction, leaving a small amount of chlorosilane, and can ensure the full progress of the reaction while avoiding the formation of by-products.
[0057] According to some specific embodiments of this application, the oxalate includes either sodium oxalate or potassium oxalate, and the oxalate readily reacts with chlorosilanes under heating conditions with few side reactions.
[0058] According to some specific embodiments of this application, the solvents in the oxalate solution and the lithium tetrafluoroborate solution are each independently selected from ester solvents, including any one of dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC). The above-mentioned ester solvents can dissolve the product lithium difluorooxalate borate, but are not easily soluble in byproducts such as sodium chloride, lithium chloride, and sodium tetrafluoroborate. Therefore, a solution of lithium difluorooxalate borate in an ester solvent with qualified acidity and chloride ion content can be obtained, resulting in high-quality lithium difluorooxalate borate with low impurity content.
[0059] According to some specific embodiments of this application, the ester solvents used in the oxalate solution and the lithium tetrafluoroborate solution are exactly the same. For example, the oxalate solution uses dimethyl carbonate, and the lithium tetrafluoroborate solution also uses dimethyl carbonate. In this way, a solution of lithium difluorooxalate borate in an ester solvent with high purity can be obtained.
[0060] According to some specific embodiments of this application, the stirring speed in the first dynamic microchannel reactor 5 is 200 r / min to 400 r / min, for example, it can be 200 r / min, 300 r / min, 400 r / min, etc. Controlling the stirring speed within the above range can make the fluid therein turbulent, thereby improving mass transfer efficiency and reaction rate.
[0061] According to some specific embodiments of this application, the Reynolds number of the fluid in the first dynamic microchannel reactor 5 is greater than or equal to 10,000. For example, the Reynolds number can be 10,000, 50,000, 60,000, 70,000, 80,000, 90,000, 100,000, 150,000, etc. Controlling the Reynolds number of the fluid in the first dynamic microchannel reactor 5 within the above range can make the fluid in it turbulent, thereby improving mass transfer efficiency and reaction rate.
[0062] According to some specific embodiments of this application, the residence time of the fluid in the first dynamic microchannel reactor 5 is 1 min to 30 min. For example, the residence time can be 1 min, 5 min, 10 min, 20 min, 30 min, etc. Controlling the residence time of the fluid in the first dynamic microchannel reactor 5 within the above range can ensure that the reaction proceeds fully, while avoiding the generation of by-products due to excessively long residence time, so that the obtained lithium difluorooxalate borate has high quality and low impurity content.
[0063] According to some specific embodiments of this application, the mass percentage of lithium tetrafluoroborate in the lithium tetrafluoroborate solution is less than or equal to 20%, for example, it can be 1%, 5%, 10%, 15%, 20%, etc. Controlling the mass percentage of lithium tetrafluoroborate within the above range can ensure that the reaction proceeds fully and avoid the formation of by-products.
[0064] According to some specific embodiments of this application, the mass flow rate ratio of the oxalate solution to the chlorosilane is (4-10):1. For example, the mass flow rate ratio can be 4:1, 5:1, 7:1, 9:1, 10:1, etc. Controlling the mass flow rate ratio within the above range can ensure the full progress of the reaction and avoid the generation of by-products.
[0065] The molar ratio of silicone oxalate in the first dynamic microchannel reactor to lithium tetrafluoroborate in the lithium tetrafluoroborate solution is 1:(1-1.05). For example, the mass flow rate ratio can be 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, etc. Controlling the molar ratio within the above range ensures the complete progress of the reaction while avoiding the formation of byproducts.
[0066] According to some specific embodiments of this application, the stirring speed in the second dynamic microchannel reactor 8 is 200 r / min to 400 r / min, for example, it can be 200 r / min, 300 r / min, 400 r / min, etc. Controlling the stirring speed within the above range can make the fluid therein turbulent, thereby improving mass transfer efficiency and reaction rate.
[0067] According to some specific embodiments of this application, the Reynolds number of the fluid in the second dynamic microchannel reactor 8 is greater than or equal to 15,000. For example, the Reynolds number can be 15,000, 20,000, 50,000, 70,000, 80,000, 90,000, 100,000, 150,000, etc. Controlling the Reynolds number of the fluid in the second dynamic microchannel reactor 8 within the above range can make the fluid in it turbulent, thereby improving mass transfer efficiency and reaction rate.
[0068] According to some specific embodiments of this application, the residence time of the fluid in the second dynamic microchannel reactor 8 is 1 min to 10 min. For example, the residence time can be 1 min, 5 min, 10 min, etc. Controlling the residence time of the fluid in the second dynamic microchannel reactor 8 within the above range can ensure that the reaction proceeds fully, while avoiding the formation of by-products due to excessively long residence time, resulting in high-quality lithium difluorooxalate borate with low impurity content.
[0069] In summary, the apparatus for the continuous preparation of lithium difluorooxalate borate proposed in this application utilizes a two-stage dynamic microchannel reactor to rapidly synthesize oxalate silica grease containing solids in the first dynamic microchannel reactor 5, reducing the separation steps after synthesis and allowing direct entry into the second fast reaction step. The gas phase is separated by distillation and reused, while the liquid undergoes continuous separation. Impurities are separated into solid industrial-grade sodium chloride, and the liquid is a qualified product, namely lithium difluorooxalate borate solution.
[0070] The embodiments of this application are described in detail below. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. In addition, unless otherwise specified, all reagents used in the following embodiments are commercially available or can be synthesized according to the methods described herein or known methods. For reaction conditions not listed, they are also readily available to those skilled in the art.
[0071] Example 1
[0072] use Figure 1 The apparatus shown is used to prepare lithium difluorooxalate borate solution:
[0073] The pressure of the entire system is increased to 0.6 MPa using high-pressure nitrogen, and the pressure of the entire device is stabilized at 0.8 MPa by a back pressure system.
[0074] The temperature of the first dynamic microchannel reactor 5 is raised to 90℃, and the stirring speed is 300 r / min. The temperature of the second dynamic microchannel reactor 8 is raised to 40℃, the temperature of the flash tank 9 is set to 110℃, and the speed of the continuous centrifuge 10 is maintained at 90 r / min.
[0075] In the feeding system, sodium oxalate and DMC solvent are stirred in the oxalate storage tank 2 by the first agitator 11 to form a homogeneous liquid (oxalate solution) with a sodium oxalate mass ratio of 10%. Subsequently, the oxalate solution (via the second feed pump 4) and chlorosilane in the chlorosilane storage tank 1 (via the first feed pump 3) are simultaneously introduced into the first dynamic microchannel reactor 5, with a mass flow ratio of 6:1 and a reaction residence time of 20 min. The resulting mixture then enters the second dynamic microchannel reactor 8, while lithium tetrafluoroborate solution is added from the lithium tetrafluoroborate storage tank 6 to the second dynamic microchannel reactor 8 via the third feed pump 7. The lithium tetrafluoroborate storage tank 6 is equipped with a second agitator 12. The lithium tetrafluoroborate in the DMC solution has a lithium tetrafluoroborate mass ratio of 9%, and the molar ratio of silicone oxalate to lithium tetrafluoroborate is 1:1.02. The reaction residence time is 5 min.
[0076] In the post-processing unit, the material exiting the second dynamic microchannel reactor 8 enters the flash tank 9, and the mixed gas of chlorosilane, fluorosilane, and DMC is discharged from the gas phase. Figure 1 The gas and liquid enter a continuous centrifuge 10, forming a sodium chloride solid with a moisture content of 15% and a product solution. Figure 1 A solution of lithium difluorooxalate borate (15% moisture content) was dried to obtain sodium chloride byproduct ( ). Figure 1 The product contains 99.55% sodium chloride, 0.07% lithium chloride, and 0.38% sodium tetrafluoroborate (solids). The solution was tested and found to contain 19.9% lithium difluorooxalate borate, 4 ppm lithium chloride, 10 ppm tetrafluoroborate (lithium tetrafluoroborate and sodium tetrafluoroborate), with the remainder being solvent DMC.
[0077] Comparative Example 1
[0078] Sodium oxalate and DMC solvent were stirred in a reactor to form a homogeneous liquid (oxalate solution) with a sodium oxalate mass ratio of 10%. The oxalate solution was then mixed with chlorosilane at a mass ratio of 6:1 and reacted at 90°C and 0.8 MPa for 20 min to obtain a mixed solution.
[0079] Sodium chloride was separated from the mixture to obtain a silicone oxalate solution. The mass percentage of lithium tetrafluoroborate in the DMC solution of lithium tetrafluoroborate was 10%. The silicone oxalate and lithium tetrafluoroborate were mixed in a molar ratio of 1:1.02 and reacted at 40°C for 5 min to obtain the reaction solution.
[0080] The reaction solution was flash-evaporated at a temperature of 110°C. A mixture of chlorosilane, fluorosilane, and DMC was discharged from the gas phase, and the liquid entered a centrifuge at a speed of 90 r / min to form a sodium chloride solid with a moisture content of 15% and a product solution. The sodium chloride solid with a moisture content of 15% was dried to obtain sodium chloride byproduct. The product solution was a solution of lithium difluorooxalate borate and an ester solvent.
[0081] The chromatogram of the solution of lithium difluorooxalate borate prepared in Example 1 with an ester solvent is shown below. Figure 2 As shown, the solution of lithium difluorooxalate borate and ester solvent prepared in Example 1 of this application has high quality.
[0082] The components of the sodium chloride byproduct and the solutions of lithium difluorooxalate borate and ester solvents in Example 1 and Comparative Example 1 were determined, and the test results are shown in Table 1.
[0083] 1. Determination of components in sodium chloride byproducts:
[0084] Sample pretreatment (dilution / filtration with deionized water), and Li was detected using ICP inductively coupled plasma. + (Column: CS12A), IC anion mode detection of BF4 - (Column: AS11-HC), corresponding to the mass percentage of lithium chloride and the mass percentage of tetrafluoroborate.
[0085] 2. Determination of solution composition of lithium difluorooxalate borate in ester solvents:
[0086] Sample pretreatment (dilution / filtration with deionized water), and detection of F using an IC ion chromatograph. - And the oxalate content, which is converted into the mass percentage of lithium difluorooxalate borate.
[0087] The test results are shown in Table 1.
[0088] Table 1
[0089]
[0090] in conclusion:
[0091] As shown in Table 1, in Example 1, the continuous preparation apparatus for lithium difluorooxalate borate according to the embodiments of this application can achieve continuous production of lithium difluorooxalate borate, improving production efficiency, and the obtained lithium difluorooxalate borate has high quality, while also yielding sodium chloride or potassium chloride as byproducts. Comparative Example 1, which did not use the continuous method apparatus of this application, obtained lithium difluorooxalate borate of lower quality.
[0092] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0093] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.
Claims
1. An apparatus for the continuous preparation of lithium difluorooxalate borate, characterized in that, include: A first dynamic microchannel reactor, wherein the first dynamic microchannel reactor is used to provide space for the reaction of oxalate and chlorosilane; The second dynamic microchannel reactor is located downstream of the first dynamic microchannel reactor and is used to receive the reaction products in the first dynamic microchannel reactor and to provide space for the reaction of the reaction products in the first dynamic microchannel reactor with lithium tetrafluoroborate. A separation device, located downstream of the second dynamic microchannel reactor, is used to separate the reaction products in the second dynamic microchannel reactor to obtain lithium difluorooxalate borate.
2. The apparatus for continuous preparation of lithium difluorooxalate borate according to claim 1, characterized in that, The separation device includes a flash tank located downstream of the second dynamic microchannel reactor, which is used to remove volatile gases from the reaction products in the second dynamic microchannel reactor.
3. The apparatus for continuous preparation of lithium difluorooxalate borate according to claim 2, characterized in that, The separation device further includes a continuous centrifuge located downstream of the flash tank, which receives the solid-liquid mixture flowing out of the flash tank and separates and removes the solid to obtain a lithium difluorooxalate borate solution.
4. The apparatus for continuous preparation of lithium difluorooxalate borate according to claim 3, characterized in that, The apparatus for the continuous preparation of lithium difluorooxalate borate further includes a back pressure system, which is connected to at least one of the flash tank, the continuous centrifuge, the first dynamic microchannel reactor, and the second dynamic microchannel reactor, and is used to increase the internal pressure of at least one of the flash tank, the continuous centrifuge, the first dynamic microchannel reactor, and the second dynamic microchannel reactor.
5. The apparatus for the continuous preparation of lithium difluorooxalate borate according to any one of claims 1 to 4, characterized in that, The apparatus for continuous preparation of lithium difluorooxalate borate further includes a chlorosilane storage tank, which is located upstream of the first dynamic microchannel reactor. A first feed pump is provided between the chlorosilane storage tank and the first dynamic microchannel reactor to transport the chlorosilane in the chlorosilane storage tank to the first dynamic microchannel reactor.
6. The apparatus for the continuous preparation of lithium difluorooxalate borate according to any one of claims 1 to 4, characterized in that, The apparatus for continuous preparation of lithium difluorooxalate borate further includes an oxalate storage tank located upstream of the first dynamic microchannel reactor. The oxalate storage tank is used to store oxalate solution. A second feed pump is provided between the oxalate storage tank and the first dynamic microchannel reactor to deliver the oxalate solution to the first dynamic microchannel reactor.
7. The apparatus for the continuous preparation of lithium difluorooxalate borate according to any one of claims 1 to 4, characterized in that, The apparatus for continuous preparation of lithium difluorooxalate borate further includes a lithium tetrafluoroborate storage tank, which is located upstream of the second dynamic microchannel reactor. The lithium tetrafluoroborate storage tank is used to store lithium tetrafluoroborate solution. A third feed pump is provided between the lithium tetrafluoroborate storage tank and the second dynamic microchannel reactor to deliver the lithium tetrafluoroborate solution to the second dynamic microchannel reactor.