Purification device and method of lithium battery additive

Abstract

The present application relates to a kind of purification device and method of lithium battery additive, purification device includes raw material storage tank, scraper film evaporator, rectifying column, condenser assembly, storage tank component, wherein the liquid flow inlet of scraper film evaporator is connected with the raw material storage tank, the scraper film evaporator is used to repeatedly circulate evaporation for reaction product source;Rectifying column is connected with the scraper film evaporator;Condenser assembly is connected with the top of the rectifying column, and the light component in the top of rectifying column is crystallized, sweating, melts in condenser assembly, and obtains purification product;Storage tank component is connected with the condenser assembly, for the storage of the purification product.Compared with prior art, the purification device in the present application is more suitable for the purification of heat-sensitive substances, with simplified operation process;While reducing the cost of product, high-purity fractionation product is obtained, and good economic benefit is obtained.

Description

Technical Field

[0001] This invention relates to the field of lithium battery additive preparation technology, and in particular to a 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. Fluoroethylene carbonate has a melting point of 18-20℃, and vinylene carbonate has a melting point of 19-22℃, both far below their boiling points. Currently, the industry commonly uses a coupled vacuum distillation and crystallization technique to achieve the purification requirements of 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, raising the energy consumption and difficulty of 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 an urgent need in this field to develop a distillation-crystallization coupled purification device that is suitable for the purification of heat-sensitive substances and has a simplified operating procedure.

[0012] There is also a need to develop a method for coupled distillation and crystallization purification. This method, combined with a distillation and crystallization coupled purification device, should be used, for example, to separate fluoroethylene carbonate and vinylene carbonate reaction liquids. It should be able to improve product purity, reduce product heat loss, and obtain high-purity fractionated products while reducing product costs, thereby achieving good economic benefits. Summary of the Invention

[0013] The purpose of this invention is to overcome the shortcomings of the prior art by providing a purification device and method for lithium battery additives. Compared with existing distillation and crystallization coupled purification devices, this invention is more suitable for the purification of heat-sensitive substances and has a simplified operation process. It can obtain high-purity fractionated products while reducing product costs, thus achieving good economic benefits.

[0014] The objective of this invention can be achieved through the following technical solutions:

[0015] The first aspect of this invention provides a purification apparatus for lithium battery additives, comprising a raw material storage tank, a scraped film evaporator, a distillation column, a condenser assembly, and a storage tank assembly, wherein specifically:

[0016] Raw material storage tanks are used to store the sources of electrolyte additive reaction products;

[0017] A scraped film evaporator, wherein the liquid inlet of the scraped film evaporator is connected to the raw material storage tank, and the scraped film evaporator is used to repeatedly circulate and evaporate the reaction product source;

[0018] A distillation column is connected to the scraped film evaporator, and the distillation column separates the light vapor components output from the scraped film evaporator.

[0019] A condenser assembly is connected to the top of the distillation column, where the light components at the top of the distillation column crystallize, sweat, and melt to obtain a purified product.

[0020] A storage tank assembly, connected to the condenser assembly, is used for storing the purified product.

[0021] Furthermore, the top of the scraped film evaporator is provided with a gas outlet, which is connected to the bottom of the distillation column.

[0022] Furthermore, the purification device for the lithium battery additive also includes a first delivery pump, which is connected to the raw material storage tank. The first delivery pump is used to deliver the electrolyte additive reaction product source to the raw material storage tank.

[0023] Furthermore, the purification device for the lithium battery additive also includes a second raw material storage tank and a second delivery pump connected to each other.

[0024] The output end of the second delivery pump is connected to the raw material storage tank, the output end of the second raw material storage tank is connected to the input end of the second delivery pump, and the bottom end of the scraped film evaporator is connected to the input end of the second raw material storage tank.

[0025] Furthermore, the condenser assembly includes a first condenser and a second condenser connected to each other;

[0026] The top of the distillation column is connected to the input ends of the first condenser and the second condenser, respectively, and the output ends of the first condenser and the second condenser are both connected to the top of the distillation column, thereby forming a reflux.

[0027] Both the first condenser and the second condenser are connected to the storage tank assembly.

[0028] Furthermore, the storage tank assembly includes a first product storage tank, a second product storage tank, and a third product storage tank, all of which are simultaneously connected to the output ends of the first condenser and the second condenser.

[0029] Furthermore, the scraped film evaporator is equipped with an externally jacketed heated evaporation cylinder, a speed transmission device, a rotating cloth distributor, and scrapers;

[0030] The scraped film evaporator uses heat transfer oil for heating and is equipped with an external circulating heating device for heating, with a heating temperature range of 20 to 200°C.

[0031] Furthermore, the distillation column is equipped with structured packing and a tray distributor;

[0032] The bottom liquid outlets of both the first and second condensers are connected to a reflux ratio controller;

[0033] Both the first and second condensers use low-temperature ethylene glycol cooling. Both the first and second condensers are equipped with external circulating heating and cooling devices, with a temperature control range of -20 to 100°C.

[0034] A second aspect of this invention provides a method for purifying lithium battery additives using the purification apparatus described above. When the apparatus of this invention is used, for example, to separate fluoroethylene carbonate and vinylene carbonate reaction solutions, battery-grade fluoroethylene carbonate and vinylene carbonate products can be obtained efficiently, reducing product heat loss. This achieves good economic benefits by reducing product costs while obtaining high-purity fractionated products. The method includes the following steps:

[0035] The electrolyte additive reaction product is fed into a scraped film evaporator, evaporated in the scraped film evaporator, and then transported to a distillation column;

[0036] The distillation product from the distillation column is fed to a condenser assembly, where it crystallizes, sweats, and melts to obtain a purified product.

[0037] Furthermore, the specific steps include:

[0038] Step 1: The lithium battery electrolyte additive reaction product source is transported to the first raw material storage tank via the first transfer pump;

[0039] Step 2: The reaction product of lithium battery electrolyte additive in the first raw material storage tank flows into a scraped thin film evaporator for heating and evaporation. The light vapor component enters the distillation column for separation, and the unevaporated heavy component flows into the second raw material storage tank. After being transported to the first raw material storage tank by the second transfer pump, it is circulated and heated.

[0040] Step 3: The gas from the top of the distillation column is liquefied by passing it through the first condenser. After the total reflux operation is completed and the temperature at the top of the distillation column stabilizes, a portion of the light and transition components is collected by using a variable reflux ratio and sent to the first and second product storage tanks. The remaining portion is refluxed back into the column, and the temperature of the heating medium in the scraped thin film evaporator is gradually increased.

[0041] Step 4: Increase the temperature of the cooling medium in the first condenser so that the gas at the top of the column after distillation is cooled, liquefied and crystallized in the first condenser, and all the uncrystallized liquid is returned to the column.

[0042] Step 5: Lower the temperature of the cooling medium in the second condenser, open the material inlet of the second condenser, so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the second condenser, and all the uncrystallized liquid is returned to the column. Close the material inlet of the first condenser, raise the temperature of the cooling medium in the first condenser, keep the temperature constant so that the crystals in the first condenser sweat, and the molten liquid is returned to the column.

[0043] Step 6: Raise the temperature of the coolant in the first condenser and keep it at a constant temperature to completely liquefy the crystals in the first condenser, thereby obtaining the lithium battery electrolyte additive product, which is then collected into the third product storage tank.

[0044] Step 7: Lower the temperature of the cooling medium in the first condenser, open the material inlet of the first condenser, so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the first condenser, and 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, keep the temperature constant so that the crystals in the second condenser sweat, and the molten liquid is returned to the column.

[0045] Step 8: Increase the temperature of the coolant in the second condenser and keep it at a constant temperature to completely liquefy the crystals in the second condenser, thereby obtaining the lithium battery electrolyte additive product, which is then collected into the third product storage tank.

[0046] Step 9: The first condenser and the second condenser alternately perform the cooling crystallization, heating melting, and melting collection process several times.

[0047] Compared with the prior art, the present invention has the following technical advantages:

[0048] 1) The purity of the fluoroethylene carbonate product obtained by separating the reaction products of lithium battery electrolyte additives using the method of the present invention can reach 99.95% or higher, the purity of the vinylene carbonate product can reach 99.995% or higher, and the purity of the dimethyl carbonate product can reach 99% or higher.

[0049] 2) This invention uses a scraped thin-film evaporator as the reboiler of the distillation column, which greatly reduces the heat loss of the raw material;

[0050] 3) By adopting a distillation-crystallization coupling method, 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;

[0051] 4) This invention uses a melt crystallization method, which introduces no new impurities, causes no pollution, and has a simple process flow and low energy consumption;

[0052] 5) This invention uses direct crystallization in the condenser, so the sweat can be directly returned to the distillation column for distillation without storage, which simplifies the process and enhances the continuity of operation.

[0053] 6) This invention does not impose any restrictions on the composition of the reaction products of the lithium battery electrolyte additives. It adopts a batch process, which has high operational flexibility and high product purity, and can be directly applied to industrial production. Attached Figure Description

[0054] Figure 1 This is a schematic diagram of a distillation and crystallization coupling device for purifying lithium battery electrolyte additives in one embodiment of the present invention.

[0055] Figure 2 This is a schematic diagram of the distillation and crystallization coupling device used for purifying lithium battery electrolyte additives in Comparative Example 1 of the present invention.

[0056] Figure 3 This is a schematic diagram of the distillation and crystallization coupling device used for purifying lithium battery electrolyte additives in Comparative Example 2 of the present invention.

[0057] In the diagram: 1. Raw material storage tank; 2. Scraped thin film evaporator; 3. Second raw material storage tank; 4. First transfer pump; 5. Second transfer pump; 6. Distillation column; 7. First condenser; 8. Second condenser; 9. First product storage tank; 10. Second product storage tank; 11. Third product storage tank; 12. Reaction product source; 13. Third condenser; 14. Third transfer pump. Detailed Implementation

[0058] One aspect of the present invention relates to a distillation-crystallization coupled purification apparatus, which includes a scraped film evaporator, a distillation column, a plurality of condensers connected to the distillation column, and a plurality of storage tanks connected to the condensers.

[0059] Figure 1 This is a schematic diagram of a distillation-crystallization coupled purification apparatus for purifying additives in lithium battery electrolytes, according to an embodiment of the present invention. As shown in the figure, the distillation-crystallization coupled purification apparatus of the present invention includes:

[0060] A scraped film evaporator 2 has a top gas outlet connected to the bottom of a distillation column 6.

[0061] Distillation column 6, which has a top liquid outlet connected to multiple condensers;

[0062] The first condenser 7 has a bottom liquid outlet, which is connected to the top of the distillation column 6 and multiple storage tanks.

[0063] In one embodiment of the present invention, the top of the scraped film evaporator 2 is fluidly connected to the lithium battery electrolyte additive reaction product source 12 via a first raw material storage tank 1 and a first delivery pump 4.

[0064] The bottom of the scraped film evaporator 2 is connected to the first raw material storage tank 1 via the second raw material storage tank 3 and the second transfer pump 5.

[0065] In one embodiment of the present invention, the scraped film evaporator 2 is equipped with an externally jacketed heated evaporation cylinder, a speed transmission device, a rotating cloth feeder, and a scraper.

[0066] The scraped film evaporator 2 uses heat transfer oil for heating. The heat transfer oil is equipped with an external circulation heating device, and the temperature range is 20 to 200°C.

[0067] In one embodiment of the invention, the distillation column 6 is equipped with high-efficiency structured packing and a tray distributor.

[0068] In one embodiment of the present invention, the number of condensers connected to the top liquid outlet of the distillation column 6 is 1 to 5, preferably 2 to 4, and more preferably 2 to 3.

[0069] In one embodiment of the present invention, the liquid outlet at the bottom of the first condenser 7 is connected to a reflux ratio controller.

[0070] In one embodiment of the present invention, the number of storage tanks connected to the bottom liquid outlet of the first condenser 7 is 1 to 5, preferably 2 to 4, and more preferably 2 to 3.

[0071] In one embodiment of the present invention, the first condenser 7 adopts 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.

[0072] Another aspect of the present invention relates to a distillation-crystallization coupled purification method for lithium battery electrolyte additives, comprising:

[0073] Step 1: The reaction products of lithium battery electrolyte additives are transported to the first raw material storage tank 1 via the first transfer pump 4;

[0074] Step 2: The reaction product of lithium battery electrolyte additive in the first raw material storage tank 1 flows into the scraped thin film evaporator 2 for heating and evaporation. The light vapor component enters the distillation column for separation, and the unevaporated heavy component flows into the second raw material storage tank 3. After being transported to the first raw material storage tank 1 by the second transfer pump 5, it is circulated and heated.

[0075] Step 3: The gas at the top of the column after distillation flows through the first condenser 7 and is liquefied. After the total reflux operation is carried out until the temperature at the top of the column stabilizes for a period of time, a portion of the light and transition components are collected using a variable reflux ratio and sent to the first product storage tank 9 and the second product storage tank 10. The remaining portion is refluxed back into the column, and the temperature of the heating medium in the scraped thin film evaporator 2 is gradually increased.

[0076] Step 4: Increase the temperature of the cooling medium in the first condenser 7 so that the gas at the top of the column after distillation is cooled, liquefied and crystallized in the first condenser 7, and all the uncrystallized liquid is returned to the column.

[0077] Step 5: Lower the temperature of the cooling medium in the second condenser 8, open the material inlet of the second condenser 8, so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the second condenser 8, and all the uncrystallized liquid is returned to the column; close the material inlet of the first condenser 7, raise the temperature of the cooling medium in the first condenser 7, and keep the temperature constant so that the crystals in the first condenser 7 sweat, and the molten liquid is returned to the column.

[0078] Step 6: Raise the temperature of the coolant in the first condenser 7 and keep it constant to completely liquefy the crystals in the first condenser 7, so as to obtain the lithium battery electrolyte additive product, which is then collected into the third product storage tank 11.

[0079] Step 7: Lower the temperature of the cooling medium in the first condenser 7, open the material inlet of the first condenser 7, so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the first condenser 7, and all the uncrystallized liquid is returned to the column; close the material inlet of the second condenser 8, raise the temperature of the cooling medium in the second condenser 8, and keep the temperature constant so that the crystals in the second condenser 8 can sweat, and the molten liquid is returned to the column.

[0080] Step 8: Raise the temperature of the coolant in the second condenser 8 and keep it constant to completely liquefy the crystals in the second condenser 8 to obtain the lithium battery electrolyte additive product, which is then collected into the third product storage tank 11.

[0081] Step 9: The first condenser 7 and the second condenser 8 alternately perform the cooling crystallization, heating melting, and melting collection process several times.

[0082] In one embodiment of the present invention, the scraper rotation speed in the scraped film evaporator 2 in step 2 is 0-200 r / min, preferably 50-150 r / min, and more preferably 80-120 r / min.

[0083] In one embodiment of the present invention, the temperature of the heat transfer medium in the scraped film evaporator 2 in step 2 is 30-90°C, preferably 45-75°C, and more preferably 50-60°C.

[0084] In one embodiment of the present invention, the operating pressure at the top of the distillation column in step 2 is 1 to 100 kPa·A, preferably 5 to 75 kPa·A, and more preferably 10 to 50 kPa·A.

[0085] In one embodiment of the present invention, the cooling medium temperature of the first condenser 7 in step 3 is -10 to 20°C, preferably -4 to 15°C, and more preferably 2 to 10°C.

[0086] In one embodiment of the present invention, the total reflux operation time in step 3 is 10 to 60 minutes, preferably 20 to 50 minutes, and more preferably 30 to 40 minutes.

[0087] In one embodiment of the present invention, the variation range of the return flow ratio in step 3 is 1:2 to 20:1, preferably 1:1 to 10:1, and more preferably 2:1 to 5:1.

[0088] In one embodiment of the present invention, when the light and transition components are collected in step 3, the top temperature of the distillation column is 20-60°C, preferably 25-50°C, and more preferably 30-40°C.

[0089] In one embodiment of the present invention, the proportion of light components extracted in step 3 is 60-120% of the proportion of light components in the raw material, preferably 75-110%, and most preferably 90-100%.

[0090] In one embodiment of the present invention, the proportion of the transition component extracted in step 3 is 70-150% of the proportion of the transition component in the raw material, preferably 85-135%, and most preferably 100-120%.

[0091] In one embodiment of the present invention, the temperature of the heat transfer medium in the scraped film evaporator 2 in step 3 is 60-120°C, preferably 75-110°C, and more preferably 90-100°C.

[0092] In one embodiment of the present invention, the operating pressure at the top of the distillation column in step 4 is 0.10–5 kPa·A, preferably 0.10–2 kPa·A, and more preferably 0.10–1 kPa·A.

[0093] In one embodiment of the present invention, the cooling medium temperature of the first condenser 7 in step 4 is 5-25°C, preferably 10-20°C, and more preferably 14-16°C.

[0094] In one embodiment of the present invention, the top temperature of the distillation column in step 4 is 25–90°C, preferably 35–80°C, and more preferably 45–70°C.

[0095] In one embodiment of the present invention, the crystallization time in the first condenser 7 in step 4 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0096] In one embodiment of the present invention, the cooling medium temperature of the second condenser 8 in step 5 is 5-25°C, preferably 10-20°C, and more preferably 14-16°C.

[0097] In one embodiment of the present invention, the crystallization time in the second condenser 8 in step 5 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0098] In one embodiment of the present invention, the cooling medium temperature of the first condenser 7 in step 5 is 15-30°C, preferably 20-25°C, and more preferably 22-23°C.

[0099] In one embodiment of the present invention, the crystallization in step 5 is kept at a constant temperature in the first condenser 7 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0100] In one embodiment of the present invention, the cooling medium temperature of the first condenser 7 in step 6 is 30-60°C, preferably 35-55°C, and more preferably 40-50°C.

[0101] In one embodiment of the present invention, the crystallization in step 6 is kept at a constant temperature in the first condenser 7 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0102] In one embodiment of the present invention, the cooling medium temperature of the first condenser 7 in step 7 is 5-25°C, preferably 10-20°C, and more preferably 14-16°C.

[0103] In one embodiment of the present invention, the crystallization time in the first condenser 7 in step 7 is 1 to 6 hours, preferably 2 to 5 hours, and more preferably 3 to 4 hours.

[0104] In one embodiment of the present invention, the cooling medium temperature of the second condenser 8 in step 7 is 15-30°C, preferably 20-25°C, and more preferably 22-23°C.

[0105] In one embodiment of the present invention, the crystallization in step 7 is kept at a constant temperature in the second condenser 8 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0106] In one embodiment of the present invention, the cooling medium temperature of the second condenser 8 in step 8 is 30-60°C, preferably 35-55°C, and more preferably 40-50°C.

[0107] In one embodiment of the present invention, the crystallization in step 8 is kept at a constant temperature in the second condenser 8 for 0.1 to 2 hours, preferably 0.2 to 1.5 hours, and more preferably 0.5 to 1 hour.

[0108] In one embodiment of the present invention, the first condenser 7 and the second condenser 8 alternately perform the cooling crystallization, heating melting and melting collection process 1 to 6 times in step 9, preferably 2 to 5 times, and more preferably 3 to 4 times.

[0109] In one embodiment of the present invention, the processing capacity of the reaction product of the lithium battery electrolyte additive is 5 to 1000 kg / h, preferably 15 to 750 kg / h, and more preferably 25 to 500 kg / h.

[0110] 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.

[0111] In one embodiment of the present invention, the diameter of the distillation column 6 is 40 mm to 800 mm, preferably 100 mm to 700 mm, and more preferably 200 mm to 600 mm.

[0112] 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.

[0113] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Any preparation methods, materials, structures, or compositional ratios not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0114] In the following embodiments, the batch 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.

[0115] In the following embodiments, the composition of the raw materials to be processed, measured by mass, is as follows:

[0116]

[0117]

[0118] Example 1

[0119] Adopting attachment Figure 1The distillation-crystallization coupled purification apparatus shown processes feedstock R-1 at a rate of 25 kg / h. The feedstock is fed into the first feedstock storage tank 1 in a single pass via the first transfer pump 4. From the first feedstock storage tank 1, the feedstock flows by gravity into a scraped-film evaporator 2 for heating. The scraper speed in the scraped-film evaporator 2 is 100 r / min, and the heat transfer medium temperature in the scraped-film evaporator 2 is 55°C. Unvaporized material enters the second feedstock storage tank 3 and is then returned to the first feedstock storage tank 1 via the second transfer pump 5. Vaporized material enters the distillation column 6 and rises to the top of the column. At the top, the pressure at the top of distillation column 6 is 20 kPa·A, the temperature of the cooling medium in the first condenser 7 is 10°C, and the total reflux operation lasts for 30 minutes. The top temperature of distillation column 6 is 35°C. During the light component collection stage, the reflux ratio is set to 2:1, and 60% of the collected light component enters the first product storage tank 9. During the transition component collection stage, the reflux ratio is set to 5:1, and 9% of the collected light component and transition component enter the second product storage tank 10. During the collection process, the temperature of the heat transfer medium in the scraped film evaporator 2 gradually increases to 90°C. The temperature of the cooling medium in the first condenser 7 is then increased to 14°C, the pressure at the top of distillation column 6 is 1 kPa·A, and the top temperature of distillation column 6 is 60°C. Fluoroethylene carbonate is cooled and crystallized in the first condenser 7, and all uncrystallized material is refluxed back into distillation column 6. The crystallization operation lasts for 3 hours. The temperature of the cooling medium in the second condenser 8 is reduced to 14°C, and the liquid inlet of the first condenser 7 is closed. Fluoroethylene carbonate is cooled and crystallized in the second condenser 8, and all the uncrystallized material is returned to the distillation column 6. The crystallization operation lasts for 3 hours. At the same time, the temperature of the cooling medium in the first condenser 7 is raised to 22°C and kept at a constant temperature for 1 hour. All the swollen liquid is returned to the distillation column 6. Then, the temperature of the cooling medium in the first condenser 7 is raised to 45°C and kept at a constant temperature for 0.5 hours. The melted liquid is high-purity fluoroethylene carbonate, which is then transported to the third product storage tank 11 for storage. The temperature of the cooling medium in the first condenser 7 is reduced to 14°C, and the liquid inlet of the second condenser 8 is closed. Fluoroethylene carbonate crystallizes in the first condenser 7, and all uncrystallized material is returned to the distillation column 6. The crystallization process lasts for 3 hours. Simultaneously, the temperature of the cooling medium in the second condenser 8 is raised to 22°C and maintained at this temperature for 1 hour. All the evaporated liquid is returned to the distillation column 6. Then, the temperature of the cooling medium in the second condenser 8 is raised to 45°C and maintained at this temperature for 0.5 hours. The melted liquid is high-purity fluoroethylene carbonate and is transported to the third product storage tank 11 for storage. The first condensers 7 and 8 alternately perform the cooling crystallization, heating evaporation, and melting collection steps, repeating this process four times. The resulting product is designated P-1.

[0120] Example 2

[0121] Adopting attachment Figure 1The distillation-crystallization coupled purification apparatus shown processes R-2 as feedstock at a rate of 30 kg / h. The feedstock is fed into the first feedstock storage tank 1 via a first transfer pump 4. From the first feedstock storage tank 1, the feedstock flows by gravity into a scraped-film evaporator 2 for heating. The scraper speed in the scraped-film evaporator 2 is 90 r / min, and the heat transfer medium temperature in the scraped-film evaporator 2 is 55℃. Unvaporized material enters the second feedstock storage tank 3 and is then returned to the first feedstock storage tank 1 via a second transfer pump 5. Vaporized material enters the distillation column 6 and rises to the top of the column. The pressure at the top of the distillation column 6 is... At 30 kPa·A, the cooling medium temperature in the first condenser 7 is 10°C. Total reflux operation lasts 30 minutes. The top temperature of distillation column 6 is 30°C. During the light component extraction stage, the reflux ratio is set to 2:1. 15% of the extracted light component enters the first product storage tank 9. During the transition component extraction stage, the reflux ratio is set to 5:1. 43% of the extracted transition component enters the second product storage tank 10. 6% of the extracted transition component enters the first product storage tank 9. During extraction, the heat transfer medium temperature in the scraped film evaporator 2 gradually increases to 75°C. The cooling medium temperature in the first condenser 7 is raised to 15°C. The top pressure of distillation column 6 is 1 kPa·A, and the top temperature of distillation column 6 is 45°C. Fluoroethylene carbonate crystallizes in the first condenser 7. All uncrystallized material is refluxed back into distillation column 6. Crystallization operation lasts 2 hours. The temperature of the cooling medium in the second condenser 8 is reduced to 15°C, and the liquid inlet of the first condenser 7 is closed. Fluoroethylene carbonate is cooled and crystallized in the second condenser 8, and all the uncrystallized material is returned to the distillation column 6. The crystallization operation lasts for 2 hours. At the same time, the temperature of the cooling medium in the first condenser 7 is raised to 21°C and kept at a constant temperature for 1 hour. All the saturated liquid is returned to the distillation column 6. Then, the temperature of the cooling medium in the first condenser 7 is raised to 40°C and kept at a constant temperature for 0.5 hours. The melted liquid is high-purity fluoroethylene carbonate, which is then transported to the third product storage tank 11 for storage. The temperature of the cooling medium in the first condenser 7 is reduced to 15°C, and the liquid inlet of the second condenser 8 is closed. Fluoroethylene carbonate crystallizes in the first condenser 7, and all uncrystallized material is returned to the distillation column 6. The crystallization operation lasts for 2 hours. Simultaneously, the temperature of the cooling medium in the second condenser 8 is raised to 21°C and maintained at this temperature for 1 hour. All the evaporated liquid is returned to the distillation column 6. Then, the temperature of the cooling medium in the second condenser 8 is raised to 40°C and maintained at this temperature for 0.5 hours. The melted liquid is high-purity vinylene carbonate, which is then transported to the third product storage tank 11 for storage. The first condensers 7 and 8 alternately perform the cooling crystallization, heating evaporation, and melting collection steps, repeating this process four times. The resulting product is designated P-2.

[0122] Comparative Example 1

[0123] Adopting attachment Figure 2The 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. The first raw material storage tank 1 and the raw material storage tank 2 are removed. Otherwise, it is the same as in Example 1. The product number is P-3.

[0124] Comparative Example 2

[0125] Adopting attachment Figure 3The distillation-crystallization coupled purification apparatus shown processes feedstock R-1 at a rate of 25 kg / h. The feedstock is fed into the first feedstock storage tank 1 in a single pass via the first transfer pump 4. From the first feedstock storage tank 1, the feedstock flows by gravity into a scraped-film evaporator 2 for heating. The scraper speed in the scraped-film evaporator 2 is 100 r / min, and the heat transfer medium temperature in the scraped-film evaporator 2 is 55°C. Unvaporized material enters the second feedstock storage tank 3 and is then returned to the first feedstock storage tank 1 via the second transfer pump 5. Vaporized material enters the distillation column 6 and rises to the top of the column. The pressure at the top of distillation column 6 is 20 kPa·A, the temperature of the cooling medium in the third condenser 13 is 10°C, and the total reflux operation lasts for 30 minutes. The temperature at the top of distillation column 6 is 35°C. During the light component collection stage, the reflux ratio is set to 2:1, and 60% of the collected light component enters the first product storage tank 9. During the transition component collection stage, the reflux ratio is set to 5:1, and 9% of the collected light component and transition component enter the second product storage tank 10. During the collection process, the temperature of the heat transfer medium in the scraped film evaporator 2 gradually increases to 90°C. The temperature of the cooling medium in the third condenser 13 is then increased to 20°C, the pressure at the top of distillation column 6 is 1 kPa·A, and the temperature at the top of distillation column 6 is 60°C. After cooling in the third condenser 13, fluoroethylene carbonate flows into the first condenser 7 for crystallization. The temperature of the cooling medium in the first condenser 7 is 14°C. All uncrystallized material is refluxed back into distillation column 6 via the third transfer pump 14. The crystallization operation lasts for 3 hours. The temperature of the cooling medium in the second condenser 8 is reduced to 14°C, and the liquid inlet of the first condenser 7 is closed. Fluoroethylene carbonate crystallizes in the second condenser 8, and all the uncrystallized material is returned to the distillation column 6 via the third transfer pump 14. The crystallization operation lasts for 3 hours. At the same time, the temperature of the cooling medium in the first condenser 7 is raised to 22°C and kept at a constant temperature for 1 hour. All the swollen liquid is returned to the distillation column 6 via the third transfer pump 14. Then, the temperature of the cooling medium in the first condenser 7 is raised to 45°C and kept at a constant temperature for 0.5 hours. The melted liquid is high-purity fluoroethylene carbonate, which is then transported to the third product storage tank 11 for storage. The temperature of the cooling medium in the first condenser 7 is reduced to 14°C, and the liquid inlet of the second condenser 8 is closed. Fluoroethylene carbonate crystallizes in the first condenser 7, and all uncrystallized material is returned to the distillation column 6 via the third transfer pump 14. The crystallization operation lasts for 3 hours. Simultaneously, the temperature of the cooling medium in the second condenser 8 is raised to 22°C and maintained at this temperature for 1 hour. All the saturated liquid is returned to the distillation column 6 via the third transfer pump 14. Then, the temperature of the cooling medium in the second condenser 8 is raised to 45°C and maintained at this temperature for 0.5 hours. The molten liquid is high-purity fluoroethylene carbonate, which is then transported to the third product storage tank 11 for storage. The first condensers 7 and 8 alternately perform the cooling crystallization, heating saturation, and melting collection steps, repeating this process four times. The resulting product is designated P-4.

[0126] Table 2 Product List

[0127] project P-1 P-2 P-3 P-4 Purity of fluoroethylene carbonate products 99.95％ / 99.8％ 99.95％ Purity of vinylene carbonate products / 99.995％ / / Product yield 85％ 80％ 45％ 83％

[0128] As can be seen from the experimental results in Table 2, when processing the same raw material R-1, the distillation column reboiler heating methods used in Example 1 and Comparative Example 1 differed. The purity of the fluoroethylene carbonate product in Comparative Example 1, which used a commonly used reboiler, was lower than that in Example 1, and the product yield was significantly lower. The crystallization purification methods used in Example 1 and Comparative Example 2 differed. The purity of the fluoroethylene carbonate product in Comparative Example 2, which used a commonly used pre-distillation followed by crystallization operation, was the same as in Example 1, and the product yield was slightly lower than that in Example 1. However, its process involved an additional condenser and a liquid transfer pump compared to Example 1, and the operation was more cumbersome.

[0129] 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 method for purifying a lithium battery additive, characterized in that, This is achieved through a purification device for lithium battery additives, which includes: Raw material storage tank (1) is used to store the electrolyte additive reaction product source (12). A scraped film evaporator (2) is provided, the liquid inlet of which is connected to the raw material storage tank (1), and the scraped film evaporator (2) is used to repeatedly circulate and evaporate the reaction product source (12); The distillation column (6) is connected to the scraped film evaporator (2); The condenser assembly is connected to the top of the distillation column (6). The condenser assembly works with the distillation column (6) to separate the light vapor components output from the scraped film evaporator (2). The light components at the top of the distillation column (6) crystallize, sweat, and melt in the condenser assembly to obtain a purified product. A storage tank assembly, connected to the condenser assembly, is used for storing the purified product; The purification method includes the following steps: The electrolyte additive reaction product source (12) is fed into the scraped film evaporator (2), evaporated in the scraped film evaporator (2), and then transported to the distillation column (6). The distillation product of the distillation column (6) is conveyed to a condenser assembly, which includes a first condenser (7) and a second condenser (8), and crystallization, sweating and melting are achieved through the following steps: Raise the temperature of the cooling medium in the first condenser (7) so that the gas at the top of the column after distillation is cooled, liquefied and crystallized in the first condenser (7), and all the uncrystallized liquid is returned to the column; Lower the temperature of the cooling medium in the second condenser (8), open the material inlet of the second condenser (8), so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the second condenser (8), and all the uncrystallized liquid is returned to the column. Close the material inlet of the first condenser (7), raise the temperature of the cooling medium in the first condenser (7), keep the temperature constant so that the crystals in the first condenser (7) sweat, and the molten liquid is returned to the column. Raise the temperature of the coolant in the first condenser (7) and keep it constant so that the crystals in the first condenser (7) are completely liquefied to obtain the lithium battery electrolyte additive product, which is then collected into the product storage tank. Lower the temperature of the cooling medium in the first condenser (7), open the material inlet of the first condenser (7), so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the first condenser (7), and all the uncrystallized liquid flows back into the column. Close the material inlet of the second condenser (8), raise the temperature of the cooling medium in the second condenser (8), keep the temperature constant so that the crystals in the second condenser (8) sweat, and the molten liquid flows back into the column. Raise the temperature of the coolant in the second condenser (8) and keep it constant so that the crystals in the second condenser (8) are completely liquefied to obtain the lithium battery electrolyte additive product, which is then collected into the product storage tank. The first condenser (7) and the second condenser (8) alternately carry out the cooling crystallization, heating melting and melting collection process several times to obtain the purified product.

2. The purification method for a lithium battery additive according to claim 1, characterized in that, The top of the scraped film evaporator (2) is provided with a gas outlet, which is connected to the bottom of the distillation column (6).

3. The purification method for a lithium battery additive according to claim 1, characterized in that, The purification device for the lithium battery additive also includes a first delivery pump (4), which is connected to the raw material storage tank (1). The first delivery pump (4) is used to deliver the electrolyte additive reaction product source (12) to the raw material storage tank (1).

4. The purification method for a lithium battery additive according to claim 1, characterized in that, The purification device for the lithium battery additive also includes a second raw material storage tank (3) and a second transfer pump (5) connected to each other. The output end of the second delivery pump (5) is connected to the raw material storage tank (1), the output end of the second raw material storage tank (3) is connected to the input end of the second delivery pump (5), and the bottom end of the scraped film evaporator (2) is connected to the input end of the second raw material storage tank (3).

5. The purification method for a lithium battery additive according to claim 1, characterized in that, The condenser assembly includes a first condenser (7) and a second condenser (8) connected to each other. The top of the distillation column (6) is connected to the input ends of the first condenser (7) and the second condenser (8), respectively, and the output ends of the first condenser (7) and the second condenser (8) are both connected to the top of the distillation column (6) to form a reflux. The first condenser (7) and the second condenser (8) are both connected to the storage tank assembly.

6. The purification method for a lithium battery additive according to claim 5, characterized in that, The storage tank assembly includes a first product storage tank (9), a second product storage tank (10), and a third product storage tank (11). The first product storage tank (9), the second product storage tank (10), and the third product storage tank (11) are all connected to the output ends of the first condenser (7) and the second condenser (8).

7. The purification method for a lithium battery additive according to claim 1, characterized in that, The scraped film evaporator (2) is equipped with an externally jacketed heated evaporation cylinder, a speed transmission device, a rotating cloth feeder and a scraper. The scraped film evaporator (2) adopts a heat transfer oil heating method and is equipped with an external circulating heating device for heating, with a heating temperature range of 20 to 200°C.

8. The purification method for a lithium battery additive according to claim 5, characterized in that, The distillation column (6) is filled with structured packing and a tray distributor; The bottom liquid outlets of the first condenser (7) and the second condenser (8) are both connected to a reflux ratio controller; Both the first condenser (7) and the second condenser (8) adopt low-temperature ethylene glycol cooling. Both the first condenser (7) and the second condenser (8) are equipped with external circulating heating and cooling devices, and the temperature control range is -20 to 100℃.

9. The purification method for a lithium battery additive according to claim 1, characterized in that, Specifically, the following steps are included: Step 1: The lithium battery electrolyte additive reaction product source (12) is transported to the first raw material storage tank (1) via the first transfer pump (4); Step 2: The reaction product of lithium battery electrolyte additive in the first raw material storage tank (1) flows into the scraped film evaporator (2) for heating and evaporation. The light vapor component enters the distillation column (6) for separation, and the unevaporated heavy component flows into the second raw material storage tank (3). It is then transported to the first raw material storage tank (1) by the second transfer pump (5) and then circulated for heating. Step 3: The gas from the top of the distillation column is liquefied by passing it through the first condenser (7). After the temperature at the top of the distillation column (6) stabilizes, a portion of the light and transition components are collected by using a variable reflux ratio and sent to the first product storage tank (9) and the second product storage tank (10). The remaining portion is returned to the column, and the temperature of the heating medium in the scraped film evaporator (2) is gradually increased. Step 4: Increase the temperature of the cooling medium in the first condenser (7) so that the gas at the top of the column after distillation is cooled, liquefied and crystallized in the first condenser (7), and all the uncrystallized liquid is returned to the column; Step 5: Lower the temperature of the cooling medium in the second condenser (8), open the material inlet of the second condenser (8), so that the gas from the top of the column after distillation is cooled, liquefied and crystallized in the second condenser (8), and all the uncrystallized liquid is returned to the column. Close the material inlet of the first condenser (7), raise the temperature of the cooling medium in the first condenser (7), and keep the temperature constant so that the crystals in the first condenser (7) sweat, and the molten liquid is returned to the column. Step 6: Raise the temperature of the coolant in the first condenser (7) and keep it constant so that the crystals in the first condenser (7) are completely liquefied to obtain the lithium battery electrolyte additive product, which is then collected into the third product storage tank (11). Step 7: Lower the temperature of the cooling medium in the first condenser (7), open the material inlet of the first condenser (7), so that the gas flow from the top of the column after distillation is cooled, liquefied and crystallized in the first condenser (7), and all the uncrystallized liquid is returned to the column. Close the material inlet of the second condenser (8), raise the temperature of the cooling medium in the second condenser (8), and keep the temperature constant so that the crystals in the second condenser (8) sweat, and the molten liquid is returned to the column. Step 8: Raise the temperature of the coolant in the second condenser (8) and keep it constant so that the crystals in the second condenser (8) are completely liquefied to obtain the lithium battery electrolyte additive product, which is then collected into the third product storage tank (11). Step 9: The first condenser (7) and the second condenser (8) alternately carry out the cooling crystallization, heating melting and melting collection process several times.

Images