CN108808093B - Preparation method of lithium tetrafluoro oxalate phosphate - Google Patents
Preparation method of lithium tetrafluoro oxalate phosphate Download PDFInfo
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- CN108808093B CN108808093B CN201810841936.5A CN201810841936A CN108808093B CN 108808093 B CN108808093 B CN 108808093B CN 201810841936 A CN201810841936 A CN 201810841936A CN 108808093 B CN108808093 B CN 108808093B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
- H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
- H01M10/0566—Liquid materials
- H01M10/0568—Liquid materials characterised by the solutes
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M10/00—Secondary cells; Manufacture thereof
- H01M10/05—Accumulators with non-aqueous electrolyte
- H01M10/052—Li-accumulators
- H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- H01M2300/00—Electrolytes
- H01M2300/0017—Non-aqueous electrolytes
- H01M2300/0025—Organic electrolyte
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
The application discloses a preparation method of lithium tetrafluoro oxalate phosphate, which comprises the following steps: (1) introducing phosphorus pentafluoride gas into a reaction kettle added with lithium oxalate and dimethyl carbonate, fully reacting for more than 5 hours at the temperature of 20-25 ℃, and filtering to obtain a lithium tetrafluoro oxalate phosphate solution; (2) dripping dichloromethane until no crystal or precipitate is separated out, and filtering to obtain a lithium tetrafluoro oxalate phosphate crude product; (3) and (5) drying. The method has the advantages of mild reaction conditions, high yield and simple process equipment, can prepare high-quality lithium tetrafluoro oxalate phosphate, can recycle condensed DMC in the reaction process, and can recycle the byproduct lithium hexafluorophosphate obtained by the reaction, thereby saving the cost.
Description
Technical Field
The application relates to the technical field of lithium ion batteries, in particular to a preparation method of lithium tetrafluoro oxalate phosphate.
Background
Since the end of the twentieth century, lithium ion batteries have become the most favored secondary batteries because of their advantages such as high energy density, high operating voltage, and long cycle life. The lithium ion battery is used as an environment-friendly clean energy source and becomes a main battery of the 21 st century electric vehicle together with the fuel battery, and the wide development prospect of the lithium ion battery brings huge development space for the lithium ion battery material industry. In the new century, two problems of energy shortage and environmental pollution are faced, and the development of high-power and high-capacity lithium ion batteries is urgently needed to meet the requirements of energy-saving and environment-friendly power automobiles or hybrid power automobiles and energy storage batteries. The research and development of a new generation of lithium ion battery with high specific energy, low price, safety and reliability is one of the focuses in the research field of chemical power sources in recent years. Through the development of the last two decades, lithium ion batteries have been widely used in portable electronic devices such as mobile phones, notebook computers, digital cameras, and the like.
The electrolyte is an indispensable component of the lithium ion battery electrolyte and is one of the determinants of the performance of the lithium ion battery. The main product in the current lithium ion battery electrolyte field is LiPF6, and the electrolyte system of the LiPF6 has the advantages of high conductivity, high electrochemical stability and the like. However, poor thermal stability of LiPF 6-based electrolytes, and the high melting point (36.4 ℃) of the EC, another solvent component necessary for the electrolyte, limit the low temperature performance of lithium ion batteries. After outdoor cycling for several years or at higher temperatures (>55 ℃) for several months, the capacity of the battery decreases significantly, making it difficult to meet the needs of high performance lithium ion batteries. This has prompted a wide range of battery researchers to develop other lithium ion battery electrolyte materials.
Lithium tetrafluoro oxalate phosphate (LiPF4C2O4), and the carbonate electrolytic liquid system of the salt has similar ionic conductivity and similar charging and discharging coulombic efficiency to LiPF6 in the temperature range of-40 to 65 ℃. The copper foil and the aluminum foil current collector also have good electrochemical stability and a wide electrochemical window in a carbonate electrolyte system. The room temperature first discharge capacity of the LiPF4C2O4 electrolyte battery is slightly lower than that of the LiPF 6-based electrolyte battery, but the impedance of the battery is higher than that of the LiPF6 electrolyte battery. The thermal stability of the LiPF6 and LiPF4C2O4 solid samples are equivalent, however, the thermal stability of the LiPF4C2O4 electrolyte system is significantly improved compared with that of the LiPF 6-based electrolyte, and the cell of the LiPF4C2O4 electrolyte obviously maintains higher capacity under high temperature conditions. After the anode surface of the LiPF4C2O4 electrolyte battery is stored at high temperature, the content of oxalic acid-based substances and LiF substances on the surface of the LiPF4C2O4 electrolyte battery is high, the surface film of the anode is thin, the anode contains the oxalic acid-based substances with high concentration, and the concentration of the LiF substances is very low. The oxalate-based materials on the surfaces of the positive and negative electrodes are relatively stable in the high-temperature storage process, which is probably the essential reason that the LiPF4C2O4 electrolyte battery has higher discharge capacity after high-temperature storage. Under the condition of high temperature of 85 ℃, the LiPF4C2O4 electrolyte is basically not decomposed, does not change color and does not precipitate after being stored for 6 months.
Disclosure of Invention
The invention provides a preparation method of lithium tetrafluoro oxalate phosphate.
The embodiment of the application provides a preparation method of lithium tetrafluorooxalate phosphate, which comprises the following steps:
(1) introducing phosphorus pentafluoride gas into a reaction kettle added with lithium oxalate and dimethyl carbonate, fully reacting for more than 5 hours at the temperature of 20-25 ℃, and filtering to obtain a lithium tetrafluoro oxalate phosphate solution;
(2) dripping dichloromethane until no crystal or precipitate is separated out, and filtering to obtain a lithium tetrafluoro oxalate phosphate crude product;
(3) and (5) drying.
Preferably, in the step (2), the lithium tetrafluoro oxalate phosphate solution is heated to 100-110 ℃ for evaporation concentration, when the lithium tetrafluoro oxalate phosphate solution is concentrated to 1/3-1/2 of the original volume, dichloromethane is dripped until no crystal or precipitate is separated out, and the temperature is reduced to 20-25 ℃ in the dripping process.
Preferably, in the step (2), the vaporized dimethyl carbonate is condensed and recycled.
Preferably, in the step (2), the filtrate obtained by filtering is dried under reduced pressure to obtain a crude lithium hexafluorophosphate product which can be reused.
Preferably, in the step (3), the lithium tetrafluoro oxalate phosphate crude product is dried in a rotary dryer, 10-20L/min of nitrogen is introduced in the drying process, and the lithium tetrafluoro oxalate phosphate crude product is dried for 10-15 hours at the temperature of 100-120 ℃.
Preferably, the mass concentration of lithium oxalate in the step (1) is 1-3%.
Preferably, the preparation of the phosphorus pentafluoride gas comprises: heating lithium hexafluorophosphate to 150-180 ℃, heating and decomposing to generate phosphorus pentafluoride gas, and introducing the phosphorus pentafluoride gas into a reaction kettle in the step (1).
Preferably, the molar ratio of the lithium hexafluorophosphate to the lithium oxalate is 2.1-2.3: 1.
Compared with the prior art, the phosphorus pentafluoride is obtained by heating and decomposing lithium hexafluorophosphate, and the phosphorus pentafluoride is reacted with lithium oxalate in DMC to obtain high-quality lithium tetrafluoro oxalate phosphate, wherein the purity of the lithium tetrafluoro oxalate phosphate is more than 99.9%, the water content of the lithium tetrafluoro oxalate phosphate is less than 10ppm, and the acid content of the lithium tetrafluoro oxalate phosphate is less than 5 ppm. And meanwhile, the condensed DMC in the reaction process can be reused, and a by-product lithium hexafluorophosphate obtained by the reaction can also be reused, so that the cost is saved.
Detailed Description
The embodiment of the application provides a method for preparing specially-made sodium hexafluorophosphate, which specifically comprises the following steps:
(1) and putting the pre-dried lithium oxalate (the purity is more than 99.9%) into the DMC subjected to water removal treatment at the temperature of 20-25 ℃, and stirring to prepare a suspension, wherein the mass concentration of the lithium oxalate is 1-3%.
(2) Heating to decompose lithium hexafluorophosphate (the purity is more than 99.9%) at 150-180 ℃, wherein the molar ratio of lithium hexafluorophosphate to lithium oxalate is 2.1-2.3: 1, introducing 2-5L/min nitrogen to introduce decomposed phosphorus pentafluoride gas into DMC suspension of lithium oxalate, and fully stirring for reaction for more than 5 hours at 20-25 ℃.
(3) And filtering out insoluble substances from the reaction solution to obtain a clear DMC solution mixed with lithium tetrafluoro oxalate phosphate and lithium hexafluorophosphate, carrying out evaporation concentration at 100-110 ℃, recycling evaporated DMC through condensation, cooling, dropwise adding dichloromethane, stopping dropwise adding dichloromethane when no crystal or precipitate is separated out, and filtering to obtain a crude product of lithium tetrafluoro oxalate phosphate. And drying the filtrate under reduced pressure to obtain crude lithium hexafluorophosphate which can be recycled.
(4) And placing the filtered lithium tetrafluoro oxalate phosphate crude product into a rotary dryer, introducing 10-20L/min of nitrogen, and drying at 100-120 ℃ for 10-15 hours to obtain white powdery lithium tetrafluoro oxalate phosphate.
The invention is further illustrated by the following examples: the invention will be better understood from the following examples. However, those skilled in the art will readily appreciate that the specific material ratios, process conditions and results thereof described in the examples are illustrative only and should not be taken as limiting the invention as detailed in the claims.
Example 1
A method for rapidly preparing sodium hexafluorophosphate specifically comprises the following steps:
(1) adding 51g of high-purity lithium oxalate and 2300g of DMC into a reaction kettle with a stirrer at the temperature of 20 ℃, and stirring to prepare a suspension, wherein the mass concentration of the lithium oxalate is 2.17%;
(2) 160g of lithium hexafluorophosphate (the molar ratio of the lithium hexafluorophosphate to the lithium oxalate is 2.105) is put into a generator, the mixture is heated and decomposed at 180 ℃, 2L/min of nitrogen is introduced, phosphorus pentafluoride gas generated by decomposition is introduced into a reaction kettle, and after the introduction of the gas is finished, the mixture is continuously stirred for 10 hours.
(3) Filtering mother liquor obtained by the reaction, removing insoluble substances, evaporating and concentrating filtrate obtained by filtering at 110 ℃, taking out and cooling when the filtrate is concentrated to one third, dropwise adding dichloromethane till no crystal appears, filtering to obtain 121.93g, and condensing and recovering evaporated DMC to obtain 1400g DMC.
(4) Drying at 120 deg.C for 15 hr while introducing 10L/min nitrogen to obtain 90.37g
(5) As a result of the detection, the product yield was 89.48%, the purity was 99.91%, the water content was 4.12ppm, and the free acid content was 3.51 ppm.
Example 2:
a method for preparing sodium hexafluorophosphate with special specification comprises the following steps:
(1) 51g of high-purity lithium oxalate and 3400g of DMC (containing 1400g of DMC obtained by condensation in the first example) were added to a reaction vessel equipped with a stirrer at 25 ℃ and stirred to prepare a suspension with a lithium oxalate mass concentration of 1.48%.
(2) 172g of lithium hexafluorophosphate is put into the generator, the molar ratio of the lithium hexafluorophosphate to the lithium oxalate is 2.263, the generator is heated and decomposed at 160 ℃, 4L/min of nitrogen is introduced, phosphorus pentafluoride gas generated by decomposition is introduced into the reaction kettle, and after the introduction of the gas is finished, the stirring is continued for 6 hours.
(3) Filtering mother liquor obtained by the reaction, removing insoluble substances, evaporating and concentrating filtrate obtained by filtering at 100 ℃, taking out and cooling when the filtrate is concentrated to be half, and then dropwise adding dichloromethane till no crystal appears to obtain 118.76 g.
(4) Then, the mixture was dried at 110 ℃ for 10 hours while introducing 15L/min of nitrogen gas, whereby 88.14g of a product was obtained.
(5) The product yield was 87.27%, the purity was 99.93%, the moisture content was 7.68ppm, and the free acid content was 2.95 ppm.
The yield and purity of each example are compared as shown in the following table:
in conclusion, the invention has the beneficial effects that: according to the invention, phosphorus pentafluoride is obtained by heating and decomposing lithium hexafluorophosphate, and the phosphorus pentafluoride is reacted with lithium oxalate in DMC, so that high-quality lithium tetrafluoro oxalate phosphate can be prepared, the purity is more than 99.9%, the moisture is less than 10ppm, and the acid content is less than 5 ppm. And meanwhile, the condensed DMC in the reaction process can be reused, and a by-product lithium hexafluorophosphate obtained by the reaction can also be reused, so that the cost is saved.
Finally, it should also be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Claims (1)
1. A preparation method of lithium tetrafluorooxalate phosphate is characterized by comprising the following steps: the preparation method comprises the following steps:
(1) introducing phosphorus pentafluoride gas into a reaction kettle added with lithium oxalate and dimethyl carbonate, fully reacting for more than 5 hours at the temperature of 20-25 ℃, and filtering to obtain a lithium tetrafluoro oxalate phosphate solution;
(2) dripping dichloromethane until no crystal or precipitate is separated out, and filtering to obtain a lithium tetrafluoro oxalate phosphate crude product;
(3) drying;
in the step (2), heating the lithium tetrafluoro oxalate phosphate solution to 100-110 ℃ for evaporation concentration, when the lithium tetrafluoro oxalate phosphate solution is concentrated to 1/3-1/2 of the original volume, dripping dichloromethane until no crystal or precipitate is separated out, and cooling to 20-25 ℃ in the dripping process;
the evaporated dimethyl carbonate can be recycled by condensation;
in the step (2), the filtrate obtained by filtering is dried under reduced pressure to obtain a lithium hexafluorophosphate crude product which can be reused;
in the step (3), the lithium tetrafluoro oxalate phosphate crude product is dried in a rotary dryer, 10-20L/min of nitrogen is introduced in the drying process, and the drying is carried out for 10-15 hours at the temperature of 100-120 ℃;
the mass concentration of the lithium oxalate in the step (1) is 1-3%;
the preparation of the phosphorus pentafluoride gas comprises the following steps: heating lithium hexafluorophosphate to 150-180 ℃, heating and decomposing to generate phosphorus pentafluoride gas, and introducing the phosphorus pentafluoride gas into a reaction kettle in the step (1); the molar ratio of the lithium hexafluorophosphate to the lithium oxalate is 2.1-2.3: 1.
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| CN109678694A (en) * | 2018-12-21 | 2019-04-26 | 东莞东阳光科研发有限公司 | A kind of preparation method of tetrafluoro oxalic acid lithium phosphate |
| CN112442086A (en) * | 2019-09-03 | 2021-03-05 | 杉杉新材料（衢州）有限公司 | Novel preparation method of phosphorus-containing lithium salt |
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| WO2015050056A1 (en) * | 2013-10-04 | 2015-04-09 | 関東電化工業株式会社 | Method for purifying phosphorus pentafluoride |
| CN105218348B (en) * | 2015-09-10 | 2017-12-12 | 天津金牛电源材料有限责任公司 | A kind of preparation method of tetrafluoro oxalic acid lithium phosphate |
| CN105399761A (en) * | 2015-10-22 | 2016-03-16 | 中国海洋石油总公司 | Preparation method of lithium difluoro(oxalato)borate |
| CN107973773A (en) * | 2017-11-14 | 2018-05-01 | 石家庄圣泰化工有限公司 | Perfluor substitutes the preparation method of disulfonic acid acid anhydride |
| CN108147436A (en) * | 2018-02-26 | 2018-06-12 | 江苏新泰材料科技有限公司 | Combined coefficient is improved in lithium hexafluoro phosphate production process reduces the synthetic method of unit consumption |
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