A continuous purification device and method of lithium battery additive

Abstract

The present application relates to a kind of lithium battery additive continuous purification device and method, purification device includes first rectifying column, first scraper film evaporator, second rectifying column, second scraper film evaporator, condensing assembly, wherein the first rectifying column is used for the purification of lithium battery electrolyte additive reaction product source;The top gas output port of first scraper film evaporator is connected with the bottom of the first rectifying column;Second rectifying column is connected with the bottom liquid output port of the first scraper film evaporator in the feed port, the top output lithium battery electrolyte additive product of the second rectifying column;The top gas output port of second scraper film evaporator is connected with the bottom of second rectifying column, and the bottom liquid output port of the second scraper film evaporator is used to output high-boiling component.Compared with prior art, the present application is more suitable for the purification of heat-sensitive substances, with simplified operation process and higher operation continuity.

Description

Technical Field

[0001] This invention relates to the field of lithium battery additive purification technology, and in particular to a continuous purification apparatus and method for lithium battery additives. Background Technology

[0002] 4-Fluoro-1,3-dioxacyclopenten-2-one (C3H3FO3, abbreviated as fluoroethylene carbonate) and 1,3-dioxacyclopenten-2-one (C3H2O3, abbreviated as vinylene carbonate) are important fine chemical materials, currently mainly used as film-forming additives in lithium-ion battery electrolytes. Both can form a good solid electrolyte interphase (SEI) film on the electrode surface, reducing further contact and reaction between the electrolyte and electrode materials. This has the effects of improving the low-temperature discharge performance of the battery, inhibiting the decomposition of the electrolyte, and increasing the discharge capacity of the battery. Moreover, the addition ratio is low, so the development prospects are good.

[0003] Currently, there are several routes for preparing fluoroethylene carbonate, such as direct fluorination, halogen exchange, and electrochemical fluorination. Among them, the halogen exchange method uses ethylene carbonate as a raw material, which is chlorinated to produce chloroethylene carbonate. After purification, it undergoes a halogen exchange reaction with potassium fluoride to obtain fluoroethylene carbonate. This method is characterized by high safety and ease of industrialization, and has high application value.

[0004] Vinylene carbonate is prepared by chlorinating ethylene carbonate to produce chloroethylene carbonate, followed by dechlorination using triethylamine as an acid-binding agent. The dechlorination process can utilize organic solvents such as tetrahydrofuran, diethyl ether, dimethyl carbonate, and ethylene carbonate. Dimethyl carbonate is the most commonly used solvent due to its high safety and ease of subsequent separation.

[0005] The reaction solutions of fluoroethylene carbonate and vinylene carbonate both contain impurities such as the product itself, light components, transition components, and heavy components. After multi-step separation and purification processes including adsorption and distillation, industrial-grade fluoroethylene carbonate and vinylene carbonate products can be obtained. Impurities in the industrial-grade products typically enter the electrolyte, leading to battery capacity decay and reduced cycle life. According to lithium battery process requirements, battery-grade fluoroethylene carbonate must have a purity greater than 99.95%, and battery-grade vinylene carbonate must have a purity greater than 99.995%.

[0006] CN102887883A discloses a continuous purification method for crude fluoroethylene carbonate, which involves pretreatment and vacuum distillation of the crude fluoroethylene carbonate to obtain purified fluoroethylene carbonate. This method can separate the target product, but achieving the desired purity using a single distillation process requires a high number of theoretical plates, a large reflux ratio, high energy consumption, and significant product heat loss.

[0007] Fluorinated ethylene carbonate has a boiling point of 200℃, and vinylene carbonate has a boiling point of 165℃. Both are thermosensitive, and even with reduced pressure distillation, prolonged exposure to the heating temperature can easily lead to side reactions. Scraped film evaporators are high-efficiency evaporators that use rotating scrapers to force film formation and can perform falling film evaporation under vacuum conditions. They are commonly used in heating processes for thermosensitive or highly viscous materials. For the distillation separation of thermosensitive materials, scraped film evaporators can be used as reboilers in the column bottom. For example, CN102125770A discloses a scraped film evaporator for continuous distillation of thermosensitive materials, which can avoid thermal decomposition caused by excessively high temperatures or prolonged residence time in high-temperature zones during heating.

[0008] Crystallization is a unit operation that effectively separates organic systems with similar boiling points but significantly different melting points. Its separation purity is typically higher than that of distillation, meeting the high-purity requirements of products. Fluorinated ethylene carbonate has a melting point of 18–20°C, and vinylene carbonate has a melting point of 19–22°C, both far below their boiling points. Currently, the industry commonly uses a coupled vacuum distillation and crystallization technique to achieve the purification requirements for battery-grade fluoroethylene carbonate and vinylene carbonate.

[0009] CN105801554A discloses a method for purifying high-purity fluoroethylene carbonate. The method involves pretreating crude fluoroethylene carbonate for decolorization and removing light components by vacuum distillation, then dissolving it in a low-boiling-point solvent. Cooling crystallization and vacuum drying are then employed to obtain refined fluoroethylene carbonate with a purity of over 99.95%. While this method can separate the target product, introducing a crystallization solvent into the system artificially increases impurities in the fluoroethylene carbonate, increasing energy consumption and difficulty in subsequent separations, and resulting in a lower product yield.

[0010] CN110655499A discloses a method and system for purifying battery-grade vinylene carbonate using falling film crystallization coupled with distillation. The crude vinylene carbonate is subjected to falling film crystallization and heating followed by sweating. The crystals are then melted by heating and distilled to obtain purified vinylene carbonate. This method can separate the target product, but it requires raw material purity as high as 98.5%, far exceeding the purity achievable with vinylene carbonate reaction solutions. This results in high raw material costs, significant differences in operation time and throughput between the distillation and crystallization units, and low consistency in the purification process.

[0011] There is a need in the field to develop a distillation-crystallization coupled continuous purification apparatus that is more suitable for the purification of heat-sensitive substances and has a simplified operating procedure and higher operational consistency.

[0012] There is also a need to develop a continuous purification method coupled with distillation and crystallization. This method, when used in conjunction with a distillation and crystallization coupled purification device for example, to separate reactants for lithium battery electrolyte additives, can advantageously improve product purity, reduce product heat loss, and obtain high-purity fractionated products while reducing product costs, thus achieving good economic benefits.

[0013] There is an urgent need in this field to develop a distillation-crystallization coupled continuous purification device that is more suitable for the purification of heat-sensitive substances, has a simplified operating procedure, and has higher operational consistency.

[0014] There is also a need to develop a continuous purification method coupled with distillation and crystallization. This method, when combined with a distillation and crystallization coupled purification device, can be used, for example, to separate reactants for lithium battery electrolyte additives. This can effectively improve product purity, reduce product heat loss, and obtain high-purity fractionated products while reducing product costs, thus achieving good economic benefits. Summary of the Invention

[0015] The purpose of this invention is to overcome the defects of the prior art by providing a distillation-crystallization coupled continuous purification apparatus and method. Compared with the existing distillation-crystallization coupled purification apparatus and method, this invention is more suitable for the purification of heat-sensitive substances, and has a simplified operation process and higher operation continuity.

[0016] The objective of this invention can be achieved through the following technical solutions:

[0017] The first aspect of this invention provides a continuous purification apparatus for lithium battery additives, comprising a first distillation column, a first scraped-film evaporator, a second distillation column, a second scraped-film evaporator, and a condensation assembly, wherein specifically:

[0018] The first distillation column is used to purify the reaction product source of lithium battery electrolyte additives. The top of the first distillation column outputs components with a boiling point lower than that of lithium battery electrolyte additives at atmospheric pressure, and the bottom of the column outputs components containing lithium battery electrolyte additives and high-boiling-point components.

[0019] The first scraped film evaporator is provided with a bottom liquid outlet and a top gas outlet, and the top gas outlet of the first scraped film evaporator is connected to the bottom of the first distillation column;

[0020] The feed inlet of the second distillation column is connected to the bottom liquid outlet of the first scraped film evaporator.

[0021] The second scraped film evaporator is provided with a bottom liquid outlet and a top gas outlet. The top gas outlet of the second scraped film evaporator is connected to the bottom of the second distillation column, and the bottom liquid outlet of the second scraped film evaporator is used to output high-boiling-point components.

[0022] A condenser assembly, connected to the top of the second distillation column, is used for the purification of the gas phase at the top of the second distillation column. The condenser assembly alternately performs cooling crystallization, heating melting, and melting extraction processes on the top fraction of the second distillation column. The bottom of the condenser assembly outputs lithium battery electrolyte additive products.

[0023] Furthermore, the condensation assembly includes a first condenser and a second condenser, wherein specifically:

[0024] The first condenser has its bottom liquid outlet connected to the top of the second distillation column;

[0025] The second condenser has its bottom liquid outlet connected to the top of the second distillation column.

[0026] Furthermore, the continuous purification device for lithium battery additives also includes a first storage tank and a first transfer pump connected to each other. The bottom liquid outlet of the first scraped film evaporator is fluidly connected to the inlet of the first scraped film evaporator through the first storage tank and the first transfer pump, and is also connected to the feed inlet of the second distillation column through the first storage tank.

[0027] Furthermore, the continuous purification device for lithium battery additives also includes a second storage tank and a second transfer pump connected to each other. The bottom liquid outlet of the second scraped film evaporator is fluidly connected to the inlet of the second scraped film evaporator through the second storage tank and the second transfer pump, and the high-boiling-point component is output through the second storage tank.

[0028] Furthermore, both the first scraped film evaporator and the second scraped film evaporator are equipped with an externally jacketed heated evaporation cylinder, a speed transmission device, a rotating cloth distributor, and scrapers.

[0029] Furthermore, both the first scraped film evaporator and the second scraped film evaporator adopt heat transfer oil heating, and the heat transfer oil is equipped with an external circulation heating device with a heating temperature range of 20 to 200°C.

[0030] Furthermore, the first and second distillation columns are equipped with structured packing and tray distributors.

[0031] Furthermore, the liquid outlet ports at the bottom of the first condenser and the second condenser are connected to a reflux ratio controller;

[0032] Both the first condenser and the second condenser adopt low-temperature ethylene glycol cooling and are equipped with an external circulating heating and cooling device. The temperature control range of the external circulating heating and cooling device is -20 to 100°C.

[0033] A second aspect of the present invention provides a continuous purification method for lithium battery additives using the purification apparatus described above, comprising the following steps:

[0034] The first distillation column is used to perform preliminary purification of the reaction product source of lithium battery electrolyte additives, and the components with a boiling point lower than that of lithium battery electrolyte additives are output from the top of the first distillation column at atmospheric pressure.

[0035] The material in the bottom of the first distillation column is repeatedly circulated and heated through the first scraped film evaporator, while maintaining bottom output.

[0036] The liquid output from the bottom of the first scraped film evaporator is purified by a second distillation column and a condensation assembly. The top fraction of the second distillation column is alternately cooled and crystallized, heated and melted and collected by the condensation assembly, thereby purifying the top product of the second distillation column and outputting a lithium battery electrolyte additive product.

[0037] The bottom material of the second distillation column is repeatedly circulated and heated through the second scraped film evaporator, and high-boiling-point components are output.

[0038] Furthermore, the specific steps include:

[0039] Step 1: The reaction product of the lithium battery electrolyte additive is conveyed to the first distillation column;

[0040] Step 2: The liquid phase in the bottom of the first distillation column flows into the first scraped film evaporator. The liquid phase in the first scraped film evaporator is heated and evaporated. The light vapor phase enters the distillation column and undergoes mass transfer with the liquid phase in the column. The unevaporated heavy components flow into the first storage tank and are then transported to the first scraped film evaporator for circulating heating via the first transfer pump.

[0041] Step 3: Remove the components with boiling points lower than those of the lithium battery electrolyte additive from the top of the first distillation column at atmospheric pressure, and collect the lithium battery electrolyte additive and high-boiling-point components from the bottom of the first storage tank and send them into the second distillation column.

[0042] Step 4: The liquid phase from the bottom of the second distillation column flows into the second scraped film evaporator. The liquid phase in the second scraped film evaporator is heated and evaporated. The light vapor phase enters the distillation column and undergoes mass transfer with the liquid phase in the column. The unevaporated heavy components flow into the second storage tank and are then transported to the inlet of the scraped film evaporator for circulating heating via the second transfer pump.

[0043] Step 5: The vapor phase at the top of the second distillation column enters the first condenser, where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the second distillation column.

[0044] Step 6: Open the material inlet of the second condenser to allow the vapor phase from the top of the second distillation column to enter the second condenser, where it will be cooled, liquefied, and crystallized. All the uncrystallized liquid will flow back into the second distillation column. Close the material inlet of the first condenser, raise the temperature of the cooling medium in the first condenser, and maintain the temperature to allow the crystals in the first condenser to sweat. The molten liquid will flow back into the second distillation column.

[0045] Step 7: Raise the temperature of the coolant in the first condenser and keep it constant to completely melt the crystals in the first condenser. Collect the lithium battery electrolyte additive product and collect the high-boiling-point component from the bottom of the second storage tank.

[0046] Step 8: Open the material inlet of the first condenser to allow the vapor phase from the top of the second distillation column to enter the first condenser, where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the column. Close the material inlet of the second condenser, raise the temperature of the cooling medium in the second condenser, and maintain the temperature to allow the crystals in the second condenser to sweat. The molten liquid is then returned to the second distillation column.

[0047] Step 9: Raise the temperature of the coolant in the second condenser and keep it at a constant temperature to completely melt the crystals in the second condenser, and collect the lithium battery electrolyte additive product. Collect the high-boiling-point component from the bottom of the second storage tank.

[0048] Step 10: The vapor phase from the top of the second distillation column enters the first condenser and the second condenser alternately for cooling crystallization, heating melting, and melting extraction.

[0049] Compared with the prior art, the present invention has the following technical advantages:

[0050] 1) The fluoroethylene carbonate product obtained by separating the reaction products of lithium battery electrolyte additives using the method of the present invention can reach a purity of 99.95% or higher, the vinylene carbonate product can reach a purity of 99.995% or higher, and the dimethyl carbonate product can reach a purity of 99% or higher.

[0051] 2) Using a scraped thin-film evaporator as the reboiler in the distillation column greatly reduces the heat loss of the raw materials.

[0052] 3) By adopting distillation-crystallization coupling, the stable high purity of the product can be ensured while reducing the height of the distillation column and the changes in the feed composition.

[0053] 4) The process adopts a melt crystallization method, which introduces no new impurities, causes no pollution, and has a simple process flow and low energy consumption.

[0054] 5) By adopting the method of direct crystallization in the condenser, the sweat can be directly returned to the distillation column for distillation without storage, which simplifies the process and enhances the continuity of operation.

[0055] 6) There are no restrictions on the composition of the reaction products of lithium battery electrolyte additives; the continuous process is adopted, the throughput is large, the operation is simple, the product purity is high, and it can be directly applied to industrial production. Attached Figure Description

[0056] Figure 1 This is a schematic diagram of a distillation and crystallization coupling device for continuous purification of lithium battery electrolyte additive reactants in one embodiment of the present invention;

[0057] Figure 2 This is a schematic diagram of the distillation and crystallization coupling device for continuous purification of lithium battery electrolyte additive reactants in Comparative Example 1 of the present invention.

[0058] Figure 3 This is a schematic diagram of the distillation and crystallization coupling device used for continuous purification of lithium battery electrolyte additive reactants in Comparative Example 2 of the present invention.

[0059] In the diagram: 1. First distillation column; 2. First scraped film evaporator; 3. First storage tank; 4. First transfer pump; 5. Second distillation column; 6. Second scraped film evaporator; 7. Second storage tank; 8. Second transfer pump; 9. First condenser; 10. Second condenser; 11. Source of reaction products for lithium battery electrolyte additives; 12. Components with boiling points lower than those for lithium battery electrolyte additives at atmospheric pressure; 13. Components containing lithium battery electrolyte additives and high-boiling-point components; 14. Lithium battery electrolyte additive products; 15. High-boiling-point components. Detailed Implementation

[0060] One aspect of the present invention relates to a distillation-crystallization coupled continuous purification apparatus, which includes multiple distillation columns connected in series, a scraped film evaporator, and a condenser.

[0061] Figure 1 This is a schematic diagram of a distillation-crystallization coupling device for the continuous purification of lithium battery electrolyte additive reactants, according to an embodiment of the present invention. As shown in the figure, the distillation-crystallization coupling purification device of the present invention includes:

[0062] A first distillation column 1 has a top liquid outlet and a bottom liquid outlet that is fluidly connected to a second distillation column 5.

[0063] The first scraped film evaporator 2 has a bottom liquid outlet and a top gas outlet, and the top gas outlet is connected to the bottom of the first distillation column 1.

[0064] The second distillation column 5 has a top liquid outlet connected to a plurality of condensers.

[0065] The second scraped film evaporator 6 has a bottom liquid outlet and a top gas outlet, the top gas outlet being connected to the bottom of the second distillation column 5;

[0066] A first condenser 9 has a bottom liquid outlet that is connected to the top of a second distillation column 5.

[0067] The second condenser 10 has a bottom liquid outlet connected to the top of the second distillation column 5.

[0068] In one embodiment of the present invention, the first distillation column 1 is fluidly connected to the lithium battery electrolyte additive reaction product source 11;

[0069] In one embodiment of the present invention, the liquid outlet at the bottom of the first scraped film evaporator 2 is connected to the inlet fluid of the first scraped film evaporator 2 via the first storage tank 3 and the first delivery pump 4.

[0070] In one embodiment of the present invention, the bottom liquid outlet of the second scraped film evaporator 6 is connected to the inlet fluid of the second scraped film evaporator 6 via the second storage tank 7 and the second transfer pump 8.

[0071] In one embodiment of the present invention, the first scraped film evaporator 2 and the second scraped film evaporator 6 are equipped with an externally jacketed heated evaporation cylinder, a speed transmission device, a rotating cloth feeder and a scraper.

[0072] The first scraped film evaporator 2 and the second scraped film evaporator 6 are heated by heat transfer oil. The heat transfer oil is equipped with an external circulation heating device, and the temperature range is 20 to 200°C.

[0073] In one embodiment of the present invention, the first distillation column 1 and the second distillation column 5 are equipped with high-efficiency structured packing and tray distributors.

[0074] In one embodiment of the present invention, the number of condensers connected to the top liquid outlet of the second distillation column 5 is 1 to 5, preferably 2 to 4, and more preferably 2 to 3.

[0075] In one embodiment of the present invention, the liquid outlets at the bottom of the first condenser 9 and the second condenser 10 are connected to a reflux ratio controller.

[0076] In one embodiment of the present invention, the first condenser 9 and the second condenser 10 adopt a low-temperature ethylene glycol cooling method, and the coolant is equipped with an external circulating heating and cooling device with a temperature range of -20 to 100°C.

[0077] Another aspect of the present invention relates to a continuous purification method for the distillation and crystallization coupled with the reaction products of lithium battery electrolyte additives, comprising:

[0078] Step 1: The reaction product of the lithium battery electrolyte additive is transported to the first distillation column 1;

[0079] Step 2: The liquid phase in the bottom of the first distillation column 1 flows into the first scraped film evaporator 2. The liquid phase in the first scraped film evaporator 2 is heated and evaporated. The light vapor phase enters the distillation column and is contacted with the liquid phase in the column for mass transfer. The unevaporated heavy components flow into the first storage tank 3 and are transported to the inlet of the scraped film evaporator for circulating heating via the first transfer pump 4.

[0080] Step 3: Remove component 12, which has a boiling point lower than that of lithium battery electrolyte additives, from the top of the first distillation column 1 at atmospheric pressure. Take out component 13 containing lithium battery electrolyte additives and high-boiling point components from the bottom of the first storage tank 3 and send it into the second distillation column 5.

[0081] Step 4: The liquid phase in the bottom of the second distillation column 5 flows into the second scraped film evaporator 6. The liquid phase in the second scraped film evaporator 6 is heated and evaporated. The light vapor phase enters the distillation column and is contacted with the liquid phase in the column for mass transfer. The unevaporated heavy components flow into the second storage tank 7 and are transported to the inlet of the scraped film evaporator for circulation heating via the second transfer pump 8.

[0082] Step 5: The vapor phase at the top of the second distillation column 5 enters the first condenser 9, where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the column.

[0083] Step 6: Open the material inlet of the second condenser 10 to allow the vapor phase from the top of the second distillation column 5 to enter the second condenser 10, where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the column. Close the material inlet of the first condenser 9, raise the temperature of the cooling medium in the first condenser 9, and maintain the temperature to allow the crystals in the first condenser 9 to sweat. The molten liquid is then returned to the column.

[0084] Step 7: Raise the temperature of the coolant in the first condenser 9 and keep it at a constant temperature to completely melt the crystals in the first condenser 9, and collect the lithium battery electrolyte additive product 14; collect the high-boiling-point component 15 from the bottom of the second storage tank 7.

[0085] Step 8: Open the material inlet of the first condenser 9 to allow the vapor phase from the top of the second distillation column 5 to enter the first condenser 9, where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the column. Close the material inlet of the second condenser 10, raise the temperature of the cooling medium in the second condenser 10, and maintain the temperature to allow the crystallized liquid in the second condenser 10 to evaporate. The molten liquid is then returned to the column.

[0086] Step 9: Raise the temperature of the coolant in the second condenser 10 and keep it at a constant temperature to completely melt the crystals in the second condenser 10, and collect the lithium battery electrolyte additive product 14; collect the high-boiling-point component 15 from the bottom of the second storage tank 7.

[0087] Step 10: The vapor phase from the top of the second distillation column 5 enters the first condenser 9 and the second condenser 10 alternately for cooling crystallization, heating melting, and melting extraction.

[0088] In one embodiment of the present invention, the scraper rotation speed in the first scraper film evaporator 2 in step 2 is 0-200 r / min, preferably 50-150 r / min, and more preferably 80-120 r / min.

[0089] In one embodiment of the present invention, the temperature of the heat transfer medium in the first scraped film evaporator 2 in step 2 is 30-90°C, preferably 45-75°C, and more preferably 50-60°C.

[0090] In one embodiment of the present invention, the operating pressure at the top of the distillation column in step 3 is 1 to 100 kPa·A, preferably 5 to 75 kPa·A, and more preferably 10 to 50 kPa·A.

[0091] In one embodiment of the present invention, the top temperature of the first distillation column 1 in step 3 is 20-60°C, preferably 25-50°C, and more preferably 30-40°C.

[0092] In one embodiment of the present invention, the temperature of the heat transfer medium in the second scraped film evaporator 6 in step 4 is 60-120°C, preferably 75-110°C, and more preferably 90-100°C.

[0093] In one embodiment of the present invention, the top operating pressure of the second distillation column 5 in step 5 is 0.10 to 5 kPa·A, preferably 0.10 to 2 kPa·A, and more preferably 0.10 to 1 kPa·A.

[0094] In one embodiment of the present invention, the top temperature of the second distillation column 5 in step 5 is 25-90°C, preferably 35-80°C, and more preferably 45-70°C.

[0095] In one embodiment of the present invention, the cooling medium temperature of the first condenser 9 in step 5 is 5-25°C, preferably 10-20°C, and more preferably 14-16°C.

[0096] In one embodiment of the present invention, the crystallization time in the first condenser 9 in step 5 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0097] In one embodiment of the present invention, the cooling medium temperature of the second condenser 10 in step 6 is 5-25°C, preferably 10-20°C, and more preferably 14-16°C.

[0098] In one embodiment of the present invention, the crystallization time in the second condenser 10 in step 6 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0099] In one embodiment of the present invention, the cooling medium temperature of the first condenser 9 in step 6 is 15-30°C, preferably 20-25°C, and more preferably 22-23°C.

[0100] In one embodiment of the present invention, the crystallization in step 6 is kept at a constant temperature in the first condenser 9 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0101] In one embodiment of the present invention, the cooling medium temperature of the first condenser 9 in step 7 is 30-60°C, preferably 35-55°C, and more preferably 40-50°C.

[0102] In one embodiment of the present invention, the crystallization in step 7 is kept at a constant temperature in the first condenser 9 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0103] In one embodiment of the present invention, the cooling medium temperature of the first condenser 9 in step 8 is 5-25°C, preferably 10-20°C, and more preferably 14-16°C.

[0104] In one embodiment of the present invention, the crystallization time in the first condenser 9 in step 8 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0105] In one embodiment of the present invention, the cooling medium temperature of the second condenser 10 in step 8 is 15-30°C, preferably 20-25°C, and more preferably 22-23°C.

[0106] In one embodiment of the present invention, the crystallization in step 8 is kept at a constant temperature in the second condenser 10 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0107] In one embodiment of the present invention, the cooling medium temperature of the second condenser 10 in step 9 is 30-60°C, preferably 35-55°C, and more preferably 40-50°C.

[0108] In one embodiment of the present invention, the crystallization in step 9 is kept at a constant temperature in the second condenser 10 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0109] In one embodiment of the present invention, the exchange cycle of the first condenser 9 and the second condenser 10 alternatingly cooling crystallization, heating melting and melting collection in step 10 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0110] In one embodiment of the present invention, the processing capacity of the reaction product of the lithium battery electrolyte additive is 5~2000 kg / h, preferably 15~1500 kg / h, and more preferably 25~1000 kg / h.

[0111] The reaction products of the lithium battery electrolyte additives include, but are not limited to: fluoroethylene carbonate, vinylene carbonate, chloroethylene carbonate, dimethyl carbonate, ethylene carbonate, difluoroethylene carbonate, triethylamine, and 2,6-di-tert-butyl-p-cresol.

[0112] In one embodiment of the present invention, the diameter of the distillation column of the first distillation column 1 is 40 mm to 1000 mm, preferably 100 mm to 900 mm, and more preferably 200 mm to 800 mm.

[0113] In one embodiment of the present invention, the diameter of the distillation column of the second distillation column 5 is 40 mm to 800 mm, preferably 100 mm to 700 mm, and more preferably 200 mm to 600 mm.

[0114] The present invention will be further described below through specific embodiments, but this is not a limitation of the present invention. Those skilled in the art can make various modifications or improvements based on the basic idea of ​​the present invention, but as long as they do not depart from the basic idea of ​​the present invention, they are all within the scope of the present invention.

[0115] Any preparation methods, materials, structures, or composition ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0116] In the following embodiments, the continuous distillation column used is equipped with high-efficiency separation packing and a distributor. The high-efficiency separation packing is wire mesh structured packing, and the distributor is a common tray distributor. Unless otherwise specified, the raw materials or processing technologies are all commercially available materials or conventional processing technologies in the art.

[0117] In the following embodiments, the composition of the raw materials to be processed, measured by mass, is as follows:

[0118]

[0119] Example 1

[0120] This embodiment uses the appendix Figure 1The distillation-crystallization coupled purification apparatus shown processes feedstock R-1 at a rate of 50 kg / h. The feedstock is fed into the first distillation column 1. The liquid phase flows by gravity from the bottom of the first distillation column 1 into the first scraped-film evaporator 2 for heating. The scraper speed in the first scraped-film evaporator 2 is 100 r / min, and the temperature of the heat transfer medium in the first scraped-film evaporator 2 is 55°C. Unvaporized material enters the first storage tank 3 and is then returned to the first scraped-film evaporator 2 via the first transfer pump 4. Vaporized material enters the first distillation column 1 and rises to the top of the column. The pressure at the top of the first distillation column 1 is 20 kJ / h. The temperature at the top of the first distillation column 1 is 35°C. Components with boiling points lower than those in the lithium battery electrolyte additive are collected from the top of the first distillation column 1 at atmospheric pressure. The lithium battery electrolyte additive and high-boiling-point components are collected from the bottom of the first storage tank 3 and enter the second distillation column 5. The liquid phase flows by gravity from the bottom of the first distillation column 2 into the second scraped film evaporator 6 for heating. The scraper speed in the second scraped film evaporator 6 is 100 r / min, and the temperature of the heat transfer medium in the second scraped film evaporator 6 is 90°C. Unvaporized material enters the second storage tank 7 and returns to the second scraped film evaporator 6 via the second transfer pump 8. Vaporized material enters the second distillation column 5 and rises to the top. The temperature of the cooling medium in the first condenser 9 is 14°C, and the pressure at the top of the second distillation column 5 is 1 kPa.A. The temperature at the top of the second distillation column 5 is 60°C. Fluoroethylene carbonate is cooled and crystallized in the first condenser 9. All uncrystallized material is returned to the second distillation column 5. The crystallization operation lasts for 3 hours. The cooling medium temperature in the second condenser 10 is 14℃. The liquid inlet of the first condenser 9 is closed. Fluoroethylene carbonate is cooled and crystallized in the second condenser 10. All uncrystallized material is returned to the second distillation column 5. The crystallization operation lasts for 3 hours. At the same time, the cooling medium temperature in the first condenser 9 is raised to 22℃ and kept at a constant temperature for 1 hour. All the swollen liquid is returned to the second distillation column 5. Then, the cooling medium temperature in the first condenser 9 is raised to 45℃ and kept at a constant temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate, which is continuously collected. The temperature of the cooling medium in the first condenser 9 is reduced to 14°C, and the liquid inlet of the second condenser 10 is closed. Fluoroethylene carbonate crystallizes in the first condenser 9, and all uncrystallized material is refluxed into the second distillation column 5. The crystallization operation lasts for 3 hours. Simultaneously, the temperature of the cooling medium in the second condenser 10 is raised to 22°C and maintained at this temperature for 1 hour. All the refluxed liquid is refluxed into the second distillation column 5. Then, the temperature of the cooling medium in the second condenser 10 is raised to 45°C and maintained at this temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate, which is continuously collected. The first condenser 9 and the second condenser 10 alternately perform cooling crystallization, heating sweating, and melting collection, with an alternation cycle of 3 hours. High-purity fluoroethylene carbonate is continuously collected from the liquid outlet of the condenser at the top of the second distillation column 5, and high-boiling-point components are continuously collected from the bottom of the second storage tank 7 at the bottom of the second distillation column 5. The product number is P-1.

[0121] Example 2

[0122] This embodiment uses the appendix Figure 1The distillation-crystallization coupled purification apparatus shown processes R-2 as feedstock at a rate of 60 kg / h. The feedstock is fed into the first distillation column 1. The liquid phase flows by gravity from the bottom of the first distillation column 1 into the first scraped-film evaporator 2 for heating. The scraper speed in the first scraped-film evaporator 2 is 90 r / min, and the temperature of the heat transfer medium in the first scraped-film evaporator 2 is 55°C. Unvaporized material enters the first storage tank 3 and is then returned to the first scraped-film evaporator 2 via the first transfer pump 4. Vaporized material enters the first distillation column 1 and rises to the top of the column. The pressure at the top of the first distillation column 1 is 30 kJ / h. The temperature at the top of the first distillation column 1 is 30°C. Components with boiling points lower than those of the lithium battery electrolyte additive are collected from the top of the first distillation column 1 at atmospheric pressure. The lithium battery electrolyte additive and high-boiling-point components are collected from the bottom of the first storage tank 3 and enter the second distillation column 5. The liquid phase flows by gravity from the bottom of the first distillation column 2 into the second scraped film evaporator 6 for heating. The scraper speed in the second scraped film evaporator 6 is 90 r / min, and the temperature of the heat transfer medium in the second scraped film evaporator 6 is 75°C. Unvaporized material enters the second storage tank 7 and returns to the second scraped film evaporator 6 via the second transfer pump 8. Vaporized material enters the second distillation column 5 and rises to the top. The temperature of the cooling medium in the first condenser 9 is 15°C, and the pressure at the top of the second distillation column 5 is 1 kPa.A. The temperature at the top of the second distillation column 5 is 45°C. Fluoroethylene carbonate is cooled and crystallized in the first condenser 9. All uncrystallized material is returned to the second distillation column 5. The crystallization operation lasts for 2 hours. The cooling medium temperature in the second condenser 10 is 15°C. The liquid inlet of the first condenser 9 is closed. Fluoroethylene carbonate is cooled and crystallized in the second condenser 10. All uncrystallized material is returned to the second distillation column 5. The crystallization operation lasts for 2 hours. At the same time, the cooling medium temperature in the first condenser 9 is raised to 21°C and kept at a constant temperature for 1 hour. All the swollen liquid is returned to the second distillation column 5. Then, the cooling medium temperature in the first condenser 9 is raised to 40°C and kept at a constant temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate and is continuously collected. The temperature of the cooling medium in the first condenser 9 is reduced to 15°C, and the liquid inlet of the second condenser 10 is closed. Fluoroethylene carbonate crystallizes in the first condenser 9, and all uncrystallized material is refluxed into the second distillation column 5. The crystallization operation lasts for 2 hours. Simultaneously, the temperature of the cooling medium in the second condenser 10 is raised to 21°C and maintained at this temperature for 1 hour. All the refluxed liquid is refluxed into the second distillation column 5. Then, the temperature of the cooling medium in the second condenser 10 is raised to 40°C and maintained at this temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate, which is continuously collected. The first condenser 9 and the second condenser 10 alternately perform cooling crystallization, heating sweating, and melting collection, with an alternation cycle of 2 hours. High-purity fluoroethylene carbonate is continuously collected from the liquid outlet of the condenser at the top of the second distillation column 5, and high-boiling-point components are continuously collected from the bottom of the second storage tank 7 at the bottom of the second distillation column 5. The product number is P-2.

[0123] Comparative Example 1

[0124] This comparative example uses the appendix. Figure 2 The distillation crystallization coupled purification device shown is used to process raw material R-1. The scraped film evaporator in Example 1 is replaced with a conventional kettle reboiler, and the first storage tank 3 and the second storage tank 7 are removed. Otherwise, it is the same as in Example 1. The product number is P-3.

[0125] Comparative Example 2

[0126] This comparative example uses the appendix. Figure 3The distillation-crystallization coupled purification apparatus shown processes feedstock R-1 at a rate of 50 kg / h. The feedstock is fed into the first distillation column 1. The liquid phase flows by gravity from the bottom of the first distillation column 1 into the first scraped-film evaporator 2 for heating. The scraper speed in the first scraped-film evaporator 2 is 100 r / min, and the temperature of the heat transfer medium in the first scraped-film evaporator 2 is 55°C. Unvaporized material enters the first storage tank 3 and is then returned to the first scraped-film evaporator 2 via the first transfer pump 4. Vaporized material enters the first distillation column 1 and rises to the top of the column. The pressure at the top of the first distillation column 1 is 20 kJ / h. The temperature at the top of the first distillation column 1 is 35℃. Components with boiling points lower than those in the lithium battery electrolyte additive are collected from the top of the first distillation column 1 at atmospheric pressure. The lithium battery electrolyte additive and high-boiling-point components are collected from the bottom of the first storage tank 3 and enter the second distillation column 5. The liquid phase flows by gravity from the bottom of the first distillation column 2 into the second scraped-film evaporator 6 for heating. The scraper speed in the second scraped-film evaporator 6 is 100 r / min, and the temperature of the heat transfer medium in the second scraped-film evaporator 6 is 90℃. Unvaporized material enters the second storage tank 7 and returns to the second scraped-film evaporator 6 via the second transfer pump 8. Vaporized material enters the second distillation column 5 and rises to the top. The cooling medium temperature in the condenser 16 is 20℃, and the cooling medium temperature in the first condenser 9 is 14℃. The pressure at the top of the second distillation column 5 is 1 kPa.A. At kPa·A, the top temperature of the second distillation column 5 is 60°C. Fluoroethylene carbonate, after being liquefied by cooling in condenser 16, enters the first condenser 9 for cooling and crystallization. All uncrystallized material is returned to the second distillation column 5 via pump 17. The crystallization operation lasts for 3 hours. The cooling medium temperature in the second condenser 10 is 14°C. The liquid inlet of the first condenser 9 is closed. Fluoroethylene carbonate, after being liquefied by cooling in condenser 16, enters the second condenser 10 for cooling and crystallization. All uncrystallized material is returned to the second distillation column 5. The crystallization operation lasts for 3 hours. Simultaneously, the cooling medium temperature in the first condenser 9 is raised to 22°C and maintained at this temperature for 1 hour. All the evaporated liquid is returned to the second distillation column 5. Then, the cooling medium temperature in the first condenser 9 is raised to 45°C and maintained at this temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate, which is continuously collected. When the temperature of the cooling medium in the first condenser 9 is reduced to 14°C, the liquid inlet of the second condenser 10 is closed. After the fluoroethylene carbonate is liquefied in the condenser 16, it enters the first condenser 9 for cooling and crystallization. All the uncrystallized material is returned to the second distillation column 5. The crystallization operation lasts for 3 hours. At the same time, the temperature of the cooling medium in the second condenser 10 is raised to 22°C and kept at a constant temperature for 1 hour. All the swollen liquid is returned to the second distillation column 5. Then, the temperature of the cooling medium in the second condenser 10 is raised to 45°C and kept at a constant temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate, which is continuously collected.The first condenser 9 and the second condenser 10 alternately perform cooling crystallization, heating sweating, and melting extraction, with an alternation cycle of 3 hours. High-purity fluoroethylene carbonate is continuously extracted from the liquid outlet of the condenser at the top of the second distillation column 5, and high-boiling-point components are continuously extracted from the bottom of the second storage tank 7 at the bottom of the second distillation column 5. The resulting product is designated as P-4.

[0127] Table 2 Product List

[0128]

[0129] As can be seen from the experimental results in Table 2, when processing the same raw material R-1, the heating methods of the distillation column used in Example 1 and Comparative Example 1 are different. The purity of the fluoroethylene carbonate product in Comparative Example 1, which uses a commonly used reboiler, is lower than that in Example 1, and the product yield is much lower than that in Example 1. The crystallization purification methods used in Example 1 and Comparative Example 2 are different. The purity of the fluoroethylene carbonate product in Comparative Example 2, which uses a commonly used distillation-then-crystallization operation, is the same as that in Example 1, and the product yield is slightly lower than that in Example 1. However, its process adds a condenser and a liquid transfer pump compared to Example 1, and the operation is more complicated than that in Example 1.

[0130] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A continuous purification method for lithium battery additives, characterized in that, This is achieved through a purification device for lithium battery additives, which includes: The first distillation column (1) is used to purify the reaction product source (11) of the lithium battery electrolyte additive. The top of the first distillation column (1) outputs a component (12) with a boiling point lower than that of the lithium battery electrolyte additive at atmospheric pressure, and the bottom of the column outputs a component (13) containing the lithium battery electrolyte additive and a high-boiling-point component. The first scraped film evaporator (2) is provided with a bottom liquid outlet and a top gas outlet, and the top gas outlet of the first scraped film evaporator (2) is connected to the bottom of the first distillation column (1). The feed inlet of the second distillation column (5) is connected to the bottom liquid outlet of the first scraped film evaporator (2); The second scraped film evaporator (6) is provided with a bottom liquid outlet and a top gas outlet. The top gas outlet of the second scraped film evaporator (6) is connected to the bottom of the second distillation column (5). The bottom liquid outlet of the second scraped film evaporator (6) is used to output high-boiling-point components (15). The condensation assembly includes a first condenser (9) and a second condenser (10). The condensation assembly is connected to the top of the second distillation column (5) and is used for the purification of the gas phase at the top of the second distillation column (5). The condensation assembly alternately performs cooling crystallization, heating melting and melting extraction processes on the top fraction of the second distillation column (5). The bottom of the condensation assembly outputs lithium battery electrolyte additive product (14). The liquid output from the bottom of the first scraped film evaporator (2) is purified by the second distillation column (5) and the condensation assembly. The top fraction of the second distillation column (5) is alternately cooled and crystallized, heated and melted and collected by the condensation assembly. This process is used to purify the top product of the second distillation column (5) and output lithium battery electrolyte additive product (14). The purification method includes the following steps: The lithium battery electrolyte additive reaction product source (11) is initially purified by the first distillation column (1), and the component (12) with a boiling point lower than that of the lithium battery electrolyte additive is output from the top of the first distillation column (1). The bottom material of the first distillation column (1) is repeatedly circulated and heated through the first scraped film evaporator (2) while maintaining bottom output; This causes the vapor phase at the top of the second distillation column (5) to enter the first condenser (9), where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the second distillation column (5). Open the material inlet of the second condenser (10) to allow the vapor phase at the top of the second distillation column (5) to enter the second condenser (10), where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the second distillation column (5). Close the material inlet of the first condenser (9) to raise the temperature of the cooling medium in the first condenser (9). Maintain the temperature so that the crystals in the first condenser (9) will sweat, and the molten liquid will be returned to the second distillation column (5). Raise the temperature of the coolant in the first condenser (9) and keep it constant so that the crystals in the first condenser (9) are completely melted and the lithium battery electrolyte additive product (14) is extracted. The high-boiling-point component (15) is extracted from the bottom of the second storage tank (7). Open the material inlet of the first condenser (9) to allow the vapor phase at the top of the second distillation column (5) to enter the first condenser (9), where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the column. Close the material inlet of the second condenser (10) to raise the temperature of the cooling medium in the second condenser (10). Maintain the temperature so that the crystals in the second condenser (10) will sweat, and the molten liquid will be returned to the second distillation column (5). Raise the temperature of the coolant in the second condenser (10), keep the temperature constant so that the crystals in the second condenser (10) are completely melted, and extract the lithium battery electrolyte additive product (14). Extract the high-boiling-point component (15) from the bottom of the second storage tank (7). This allows the gas phase from the top of the second distillation column (5) to enter the first condenser (9) and the second condenser (10) alternately for cooling crystallization, heating melting and melting extraction.

2. The continuous purification method for a lithium battery additive according to claim 1, characterized in that, The condensation assembly includes: The bottom liquid outlet of the first condenser (9) is connected to the top of the second distillation column (5); The second condenser (10) has its bottom liquid outlet connected to the top of the second distillation column (5).

3. The continuous purification method for lithium battery additives according to claim 1, characterized in that, The continuous purification device for lithium battery additives also includes a first storage tank (3) and a first transfer pump (4) connected to each other. The bottom liquid outlet of the first scraped film evaporator (2) is fluidly connected to the inlet of the first scraped film evaporator (2) through the first storage tank (3) and the first transfer pump (4), and is connected to the feed inlet of the second distillation column (5) through the first storage tank (3).

4. The continuous purification method for lithium battery additives according to claim 1, characterized in that, The continuous purification device for lithium battery additives also includes a second storage tank (7) and a second transfer pump (8) connected to each other. The bottom liquid outlet of the second scraped film evaporator (6) is fluidly connected to the inlet of the second scraped film evaporator (6) through the second storage tank (7) and the second transfer pump (8), and outputs high-boiling-point components (15) through the second storage tank (7).

5. The continuous purification method for a lithium battery additive according to claim 1, characterized in that, The first scraped film evaporator (2) and the second scraped film evaporator (6) are both equipped with an externally jacketed heating evaporation cylinder, a speed transmission device, a rotating cloth feeder and a scraper.

6. The continuous purification method for a lithium battery additive according to claim 1, characterized in that, Both the first scraped film evaporator (2) and the second scraped film evaporator (6) adopt the heat transfer oil heating method. The heat transfer oil is equipped with an external circulation heating device, and the heating temperature range is 20 to 200℃.

7. The continuous purification method for a lithium battery additive according to claim 1, characterized in that, The first distillation column (1) and the second distillation column (5) are filled with structured packing and tray distributors.

8. The continuous purification method for lithium battery additives according to claim 2, characterized in that, The liquid outlets at the bottom of the first condenser (9) and the second condenser (10) are connected to a reflux ratio controller; Both the first condenser (9) and the second condenser (10) adopt low-temperature ethylene glycol cooling and are equipped with an external circulating heating and cooling device. The temperature control range of the external circulating heating and cooling device is -20 to 100°C.

9. The continuous purification method for a lithium battery additive according to claim 1, characterized in that, The continuous purification method specifically includes the following steps: Step 1: The reaction product of the lithium battery electrolyte additive is transported to the first distillation column (1). Step 2: The liquid phase in the bottom of the first distillation column (1) flows into the first scraped film evaporator (2). The liquid phase in the first scraped film evaporator (2) is heated and evaporated. The light vapor phase enters the distillation column and is mass-transferred by contact between the vapor and liquid phase in the column. The unevaporated heavy components flow into the first storage tank (3) and are transported to the first scraped film evaporator (2) for circulating heating via the first transfer pump (4). Step 3: Remove the components (12) with boiling points lower than those of lithium battery electrolyte additives from the top of the first distillation column (1) and collect the lithium battery electrolyte additives and high-boiling-point components (13) from the bottom of the first storage tank (3) and send them into the second distillation column (5). Step 4: The liquid phase in the bottom of the second distillation column (5) flows into the second scraped film evaporator (6). The liquid phase in the second scraped film evaporator (6) is heated and evaporated. The light vapor phase enters the distillation column and is mass-transferred by contact between the vapor and liquid phase in the column. The unevaporated heavy components flow into the second storage tank (7) and are transported to the inlet of the scraped film evaporator for circulating heating via the second transfer pump (8). Step 5: The vapor phase at the top of the second distillation column (5) enters the first condenser (9), where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the second distillation column (5). Step 6: Open the material inlet of the second condenser (10) to allow the vapor phase at the top of the second distillation column (5) to enter the second condenser (10), where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the second distillation column (5). Close the material inlet of the first condenser (9) and raise the temperature of the cooling medium in the first condenser (9). Maintain the temperature so that the crystals in the first condenser (9) will sweat, and the molten liquid will be returned to the second distillation column (5). Step 7: Raise the temperature of the coolant in the first condenser (9), keep the temperature constant so that the crystals in the first condenser (9) are completely melted, and collect the lithium battery electrolyte additive product (14). Collect the high boiling point component (15) from the bottom of the second storage tank (7). Step 8: Open the material inlet of the first condenser (9) to allow the vapor phase at the top of the second distillation column (5) to enter the first condenser (9), where it is cooled, liquefied, and crystallized. All the uncrystallized liquid is returned to the column. Close the material inlet of the second condenser (10), raise the temperature of the cooling medium in the second condenser (10), and maintain the temperature to allow the crystals in the second condenser (10) to sweat. The molten liquid is then returned to the second distillation column (5). Step 9: Raise the temperature of the coolant in the second condenser (10), keep the temperature constant so that the crystals in the second condenser (10) are completely melted, and collect the lithium battery electrolyte additive product (14). Collect the high boiling point component (15) from the bottom of the second storage tank (7). Step 10: The gas phase at the top of the second distillation column (5) enters the first condenser (9) and the second condenser (10) alternately to carry out the cooling crystallization, heating melting and melting extraction process.

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