CA2259985A1 - Lipf6 production process - Google Patents
Lipf6 production process Download PDFInfo
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- CA2259985A1 CA2259985A1 CA002259985A CA2259985A CA2259985A1 CA 2259985 A1 CA2259985 A1 CA 2259985A1 CA 002259985 A CA002259985 A CA 002259985A CA 2259985 A CA2259985 A CA 2259985A CA 2259985 A1 CA2259985 A1 CA 2259985A1
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- lipf6
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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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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01D—COMPOUNDS OF ALKALI METALS, i.e. LITHIUM, SODIUM, POTASSIUM, RUBIDIUM, CAESIUM, OR FRANCIUM
- C01D15/00—Lithium compounds
- C01D15/005—Lithium hexafluorophosphate
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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
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Abstract
The invention relates to a LiPF6 production process, wherein LiF is reacted with PCl5 or PCl3 at a temperature of -20 to 300 ~C for a reaction time of 0.1 to 10 hours to give LiPF6, and LiPF6 is isolated as a solution from the reaction mixture, using ether, nitrile, sulphone, carbonate, halogenated hydrocarbon and/or tertiary amines as the solubilizing agent.
Description
CA 022~i998~i 1999-01-07 "LiPF6 ~ 11~ ~_I~;n Description This invention relates to a process of producing LiPF6. This compound is used in particular as electrolyte in batteries and as catalyst.
It is known that LiPF6 can be produced from LiF and PF5 at an elevated pressure and an elevated temperature. However, this reaction takes place with a low yield and is therefore uneco-nomic. The yield can be increased by using reactive LiF, which is obtained during the thermal decomposition of LiHF2, but the production of the reactive LiF is technically complex and involves considerable costs. In addition, the gaseous PF5 is not available on the market as raw material, but must be produced directly before the synthesis of LiPF6. Moreover, PF5 can only be handled with difficulty due to its toxicity and reactivity.
LiPF6 can also be produced from red phosphorus and LiF in the presence of HF at 200~C in a closed reactor under pressure.
Due to the corrosive properties of HF, this process can tech-nically be realized only with difficulty, and the purifica-tion of the LiPF6 thus obtained is expensive. The LiPF6 can furthermore be produced by reacting PF5 with LiF in anhydrous HF at 25~C in a closed reactor under pressure. With this process, too, the product yield is too low, and the process CA 022~998~ 1999-01-07 requires a great effort for purifying the product, as in par-ticular the quantitative separation of HF and other by-products is very difficult.
US-PS 3,607,020 furthermore proposes a process of producing LiPF6, wherein LiF is reacted with PFs in an inert organic solvent, where suitable solvents include in particular lower, saturated alkyl ethers and lower alkyl esters of aliphatic saturated monocarboxylic acids- The PFs is easily soluble in these solvents, and the process can be performed at tempera-tures between 0 and 50~C. However, it involves the disadvan-tage that directly before the execution of the process PF5 must be synthesized, as this raw material is not available on the market.
From US-PS 3,907,977 there is also known a process of produc-ing LiPF6. In this process, LiF is reacted with PF5 in aceto-nitrile as solvent at -40 to 80~C- The PFs is introduced into the LiF-acetonitrile suspension at low temperatures, and the reaction mixture is then heated to 60 to 80~C and filtered.
The filtered solution is cooled to 0~C, so that the complex compound Li(CH3CN)4PF6 is precipitated- This complex can be liberated from acetonitrile by heating the same to 80OC in a vacuum, and can be converted to LipF6. As raw material, this process also utilizes PFs, which can be handled only with difficulty.
From JP-OS 60-251 109 there is finally known a process of producing LiPF6, where PCls is reacted with LiF in liquid HF
at -78 to 0~C. Due to the use of liquid HF as solvent it is necessary to purify the end product from HF, which causes certain problems. Moreover, anhydrous HF is very toxic. This known process employs inexpensive raw materials, but requires an expensive low-temperature technology.
CA 022~998~ l999-0l-07 Since the compound LiPF6 is only of interest as industrial raw material when it can be produced in the purest possible form from inexpensive raw materials by means of a simple technically controllable process, it is the object underlying the invention to create a process of producing the aforemen-tioned compound, which employs generally available inexpen-sive raw materials, supplies process products of high purity, and can be performed under most simple process conditions, where the use and the formation of corrosive and toxic sub-stances should possibly be avoided.
The object underlying the invention is solved by a process of producing LiPF6, wherein LiF iS reacted with PC15 or POCl3 to form LiPF6 at a reaction temperature of -20 to 300OC for a reaction time of 0.1 to 10 hours corresponding to the chemi-cal equations a) PCl5 + 6LiF - > 5LiCl + LiPF6 b) 4POCl3 + 18LiF - > 12LiCl + Li3Po4 + 3LiPF6 and wherein the LiPF6 is isolated from the reaction mixture in the form of a solution, where ethers, nitriles, esters, sulfones, carbonates, halogenated hydrocarbons and/or terti-ary amines are used as solvent.
This process employs raw materials which are offered on the market as inexpensive products, and which are mostly avail-able in a very pure form- The use of pure LiF is very advan-tageous, but it is also possible to use LiF contaminated with minor amounts of other alkali and alkaline earth fluorides.
The chemical reactions utilized for the inventive process supply the end product LiPF6 in a high yield, where the other reaction products can easily be separated and recovered. The solvents required for performing the process in accordance with the invention, which solvents must be acid-free and aprotic, are available in a high purity and can be recovered CA 022~998~ 1999-01-07 .
and purified by means of simple methods. The required reac-tion times and reaction temperatures are easy to control on a technical scale even in the presence of the raw materials re-quired for the execution of the process, as corresponding re-actors are nowadays provided by the process technology. It is possible to also use PBrs and POBr3 instead of PC15 and POCl3 for performing the inventive process, but it turned out that these bromium compounds are very expensive and hardly avail-able on the market. Therefore, PBrs and POBr3 are not suited for performing the inventive process on a technical scale.
In the process in accordance with the invention diethyl ether is preferably used as solvent, as LiPF6 is particularly eas-ily soluble in diethyl ether.
In the process in accordance with the invention, the reaction times are shortened and/or the yields are increased, when an excess of 0.1 to 2 mol LiF, based on 1 mol PC15 and POCl3, is present.
The process in accordance with the invention can on the one hand be performed such that the reaction is first of all ef-fected for 0.1 to 5 hours at 150 to 300~C and subsequently for 0.1 to 5 hours at 60 to 120~C, and that the LiPF6 is then extracted from the solid reaction mixture by means of the solvent at 0 to 80~C. This procedure is performed in a closed reactor under the pressure caused by the starting substances and the reaction temperature. At 150 to 300~C PF5 is probably formed in situ and subsequently reacts with LiF to form the end product at 60 to 120~C. During the extraction of the cooled, solid reaction mixture by means of a solvent, the end product goes into solution and can be filtered off the solid reaction residue. The residue consists of LiCl, LiF and pos-sibly lithium phosphate, which can be processed according to known methods. The solvent used for extraction can be puri-fied by distillation or again be utilized for extraction.
.
CA 022~998~ 1999-01-07 To be able to utilize the inexpensive raw material PCl3 for the inventive process, it is provided in accordance with the invention that PCls and POC13 are produced in situ from PC13 during the reaction stage taking place at 150 to 300~C corre-sponding to the chemical equations c) PC13 + Cl2 - > PCl5 d) 2PC13 + ~2 - > 2POC13.
It is quite obvious for the man skilled in that art that the execution of the inventive process corresponding to the gas-solids reaction is not impaired by the presence of chlorine and oxygen.
The process in accordance with the invention can on the other hand be performed such that the reaction is effected for 0.1 to 5 hours at -20 to 100~C in the presence of the solvent, and that the solution containing LiPF6 is filtered off the insoluble reaction products.
What is particularly advantageous in this alternative proce-dure is the fact that relatively low reaction temperatures can be employed, where reaction temperatures of 0 to 80~C are preferred in accordance with the invention. Moreover, the re-action in the solvent takes place with a good yield, the LiPF6 is easily soluble in the solvent, and the other reac-tion products can be separated in solid form by means of fil-tration. The PCls can advantageously be reacted with LiF in the solvents diethyl ether as well as dimethyl, ethylene and propylene carbonate, whereas the solvents acetonitrile, tet-rahydrofuran and methyltetrahydrofuran turned out to be par-ticularly useful for reacting POC13 with LiF.
In accordance with the invention it is provided that before or during the reaction taking place in the solvent the PCl5 CA 022~998~ 1999-01-07 is produced by chlorinating PC13 in the presence of the sol-vent at -20 to 100~C according to the equation e) PCl3 + Cl2 -> PCl5.
In this way, the inexpensive raw material PC13 is also avail-able for the variant of the inventive process which is per-formed at -20 to 100~C in the presence of a solvent. The chlorination of PC13 is highly exothermal (~H = 125kJ/mol).
The economy of the inventive process can be improved in that the solvent contains 5 to 50 wt-% liquid, aliphatic or aro-matic hydrocarbons. This measure does not negatively influ-ence the solubility of the process product LiPF6; however, the use of inexpensive, liquid hydrocarbons leads to a reduc-tion of the process costs.
Finally, it is provided in accordance with the invention that the LiPF6 is obtained from the solution containing LiPF6 in crystalline form by evaporating the solvent. The separation of the solvent from the process product by distillation is advantageously promoted by an inert gas stream and/or by means of a distillation under a reduced pressure. It was noted that the used organic solvents can be removed from the process product much easier and with less residues than HF.
When performing the inventive process it should of course be made sure that no water is present in the individual reac-tions. The used solvents should almost be anhydrous. It has turned out that the raw materials provided for the execution of the inventive process are in any case easier to handle than gaseous PFs. The LiF is used in a finely crystalline form. In the gas-solids reactions belonging to the inventive process and in the reactions taking place in a liquid phase, very little or no PFs was identified in the reaction mixtures upon completion of the reaction; it is, however, assumed that .
CA 022~998~ 1999-01-07 PF5 is formed in situ in the individual reactions and is then decomposed immediately. The reaction time of the inventive reactions can be shortened by stirring or grindingly stir-ring. The reaction of LiF with POC13 performed in a solvent should take place in a closed, pressure-tight reactor, in or-der to avoid that the POF3 formed intermediately escapes from the reactor uncontrolled. The relatively low pressures occur-ring here are easy to control.
The processing of the residue obtained in the individual re-actions, which contains LiCl or LiCl and Li3Po4 as well as excess LiF, iS effected such that the residue is treated with water. LiF and Li3P04 are obtained in insoluble form. If PCl5 is used as raw material, the insoluble residue exclusively consisting of LiF can again be used as raw material for the inventive process upon filtering and drying the same. When treated with water, LiCl goes into solution and can be recov-ered from the aqueous solution and be reused in some other way.
It is known that the process product LiPF6 forms addition products with water, so that the suitability of this sub-stance, in particular as electrolyte for batteries, is re-stricted. For removing residual traces of water, which get into the reaction system in particular by the used raw mate-rials, it is provided that the solutions of LiPF6 produced in accordance with the inventive process are reacted with or-ganolithium compounds, in particular methyllithium or butyl-lithium, or with lithium hydride, before further processing the same. Together with water, these compounds form lithium hydroxide as well as hydrocarbons such as methane or butane and hydrogen. The lithium hydroxide can be filtered off, whereas the hydrocarbons or the hydrogen escape from the so-lution as gases. However, the water content of the product solutions is small in any case, as LiCl, which is formed in the inventive process, is hygroscopic and therefore already .
CA 022~998~ 1999-01-07 largely binds the water contained in the solutions. The dry-ing effect of the LiCl provides for the use of solvents which need not be anhydrous quantitatively, which advantageously reduces the costs for the dehydration of the solvent.
Purifying the LiPF6 may be effected by recrystallizing in the solvent, as the product is easily soluble in the solvent at an elevated temperature and less easily soluble at a lower temperature. Diethyl ether is particularly useful as solvent and suited for recrystallizing the LiPF6, where the LiPF6 is dissolved at 30 to 40~C and recrystallized at 0 to 10~C. The product produced in accordance with the inventive process in any case has a purity > 99.0 % and in general even a purity > 99.8 %. The product is virtually anhydrous; the product-containing solutions obtained after the extraction or filtra-tion still have a water content < 10 ppm (determined accord-ing to K. Fischer). The process product is marketed either in the form of solutions or in solid form.
In the gas-solids reactions, the product yield generally is 80 to 95 % after the extraction, and in the reactions per-formed in a solvent the yield is 90 to 96 % after the filtra-tion.
The subject-matter of the invention will subsequently be ex-plained in detail with reference to embodiments.
Example 1 500 g (2.4 mol~ PCls (purity 99 %) and 448 g (17.3 mol) dried LiF were filled into a stainless steel autoclave and heated to 300~C within one hour by stirring. This temperature was maintained for about one hour- There was achieved an autoge-nous pressure of 55 bar. Then, the temperature was decreased to about 80~C, and stirring was effected at this temperature . .
- CA 022~998~ 1999-01-07 for 3 hours. Upon cooling to room temperature, a final pres-sure of about 5 bar was achieved.
The gaseous reaction products were absorbed in sodium hydrox-ide solution. They contained about 1 % of the used phosphorus as volatile halogen compounds- The white, finely powdered residue was filled into a glass apparatus under an inert gas, mixed with 1500 ml diethyl ether and stirred for about 30 minutes. The insoluble constituents (573.4 g, consisting of a mixture of LiCl and LiF) were filtered off via a fritted-glass filter (G3) and rinsed three times with about 200 ml diethyl ether. The water content in the combined filtrates was < 10 ppm (Karl Fischer titration). A lP-NMR spectrum ex-clusively revealed a signal at -143.5 ppm (septet) for the formed PF6. Upon separation of the diethyl ether 335 g (yield 91.9 %) finely powdered LiPF6 were left. The product con-tained 0.2 % chloride and had a purity of about 99.8 %.
Example 2 To 8.04 g (0.31 mol) dried LiF, suspended in 80 ml commer-cially available propylene carbonate (purity 99 %) 8.97 g (0.043 mol) PCls were added within about 15 minutes. The tem-perature of the reaction mixture increased from 20 to about 32~C. After stirring for one hour at room temperature, the reaction was completed ( P-NMR spectrum only revealed a sig-nal at -143.5 ppm). The filtered solution (90.8 g) had a wa-ter content < 10 ppm and contained 6.2 g LiPF6 (yield 86.1 %). By rinsing the precipitate with propylene carbonate the yield could be increased to 90 %.
Example 3 In a double-walled reactor 117.5 g (0,56 mol) PCls were added to a suspension of 96.7 g (3.73 mol) LiF in 480 ml diethyl ether at a reaction temperature of 20OC within about 30 min-CA 022~998~ 1999-01-07 utes. By means of cooling, the temperature was maintained at 22~C. Subsequently, stirring was effected for about one hour at 20~C, and the reaction solution was liberated from insolu-ble constituents (127.1 g, mixture of LiCl and LiF) by fil-tering the same. The filtration residue was rinsed three times with 50 ml diethyl ether each- The solvent was con-densed off the combined filtrates, and the residue was dried in a vacuum until the weight remained constant. There were left 82.0 g (yield 95.7 %) pure LiPF6.
Example 4 27.7 g (0.2 mol) PC13 were dissolved in 99 g methylene chlo-ride. Into this solution, dried chlorine was introduced at 20 to 30~C by cooling the same- The chlorination of PC13 took place exothermally and was terminated when no further reac-tion heat was observed. The PCls formed was contained in methylene chloride partly in dissolved form and partly in suspended form. Excess chlorine was washed out of the suspen-sion with a dried stream of nitrogen. Subsequently, the sus-pension was diluted with 105.5 g diethyl ether and then charged with 37.4 g (1.44 mol) LiF for a period of 50 min-utes. The exothermal reaction of PCls with LiF started imme-diately and was maintained at 20 to 28~C by means of cooling.
When the entire amount of LiF had been introduced into the suspension, stirring was continued for two hours. Then, the solids were filtered off, the solvent was distilled off the filtrate, and the remaining LiPF6 was purified by recrystal-lizing the same in diethyl ether- The yield was 83 %, based on PCl3.
Example 5 In an autoclave, 8.65 g POC13 (65.4 mmol) and 9.8 g (370 mmol) finely divided, dry LiF were mixed with 50 ml tetrahy-drofuran. The mixture was grindingly stirred for 9 hours at .__ CA 022~998~ 1999-01-07 25~C, where an excess pressure of about 0.1 bar was produced.
Upon cooling, the autoclave was relieved, and the reaction mixture was filtered- In the filtrate, no POC13 could be de-tected. The tetrahydrofuran was filtered off the filtrate in a vacuum, and the LiPF6 was left as product, which was puri-fied by recrystallizing the same with diethyl ether.
It is known that LiPF6 can be produced from LiF and PF5 at an elevated pressure and an elevated temperature. However, this reaction takes place with a low yield and is therefore uneco-nomic. The yield can be increased by using reactive LiF, which is obtained during the thermal decomposition of LiHF2, but the production of the reactive LiF is technically complex and involves considerable costs. In addition, the gaseous PF5 is not available on the market as raw material, but must be produced directly before the synthesis of LiPF6. Moreover, PF5 can only be handled with difficulty due to its toxicity and reactivity.
LiPF6 can also be produced from red phosphorus and LiF in the presence of HF at 200~C in a closed reactor under pressure.
Due to the corrosive properties of HF, this process can tech-nically be realized only with difficulty, and the purifica-tion of the LiPF6 thus obtained is expensive. The LiPF6 can furthermore be produced by reacting PF5 with LiF in anhydrous HF at 25~C in a closed reactor under pressure. With this process, too, the product yield is too low, and the process CA 022~998~ 1999-01-07 requires a great effort for purifying the product, as in par-ticular the quantitative separation of HF and other by-products is very difficult.
US-PS 3,607,020 furthermore proposes a process of producing LiPF6, wherein LiF is reacted with PFs in an inert organic solvent, where suitable solvents include in particular lower, saturated alkyl ethers and lower alkyl esters of aliphatic saturated monocarboxylic acids- The PFs is easily soluble in these solvents, and the process can be performed at tempera-tures between 0 and 50~C. However, it involves the disadvan-tage that directly before the execution of the process PF5 must be synthesized, as this raw material is not available on the market.
From US-PS 3,907,977 there is also known a process of produc-ing LiPF6. In this process, LiF is reacted with PF5 in aceto-nitrile as solvent at -40 to 80~C- The PFs is introduced into the LiF-acetonitrile suspension at low temperatures, and the reaction mixture is then heated to 60 to 80~C and filtered.
The filtered solution is cooled to 0~C, so that the complex compound Li(CH3CN)4PF6 is precipitated- This complex can be liberated from acetonitrile by heating the same to 80OC in a vacuum, and can be converted to LipF6. As raw material, this process also utilizes PFs, which can be handled only with difficulty.
From JP-OS 60-251 109 there is finally known a process of producing LiPF6, where PCls is reacted with LiF in liquid HF
at -78 to 0~C. Due to the use of liquid HF as solvent it is necessary to purify the end product from HF, which causes certain problems. Moreover, anhydrous HF is very toxic. This known process employs inexpensive raw materials, but requires an expensive low-temperature technology.
CA 022~998~ l999-0l-07 Since the compound LiPF6 is only of interest as industrial raw material when it can be produced in the purest possible form from inexpensive raw materials by means of a simple technically controllable process, it is the object underlying the invention to create a process of producing the aforemen-tioned compound, which employs generally available inexpen-sive raw materials, supplies process products of high purity, and can be performed under most simple process conditions, where the use and the formation of corrosive and toxic sub-stances should possibly be avoided.
The object underlying the invention is solved by a process of producing LiPF6, wherein LiF iS reacted with PC15 or POCl3 to form LiPF6 at a reaction temperature of -20 to 300OC for a reaction time of 0.1 to 10 hours corresponding to the chemi-cal equations a) PCl5 + 6LiF - > 5LiCl + LiPF6 b) 4POCl3 + 18LiF - > 12LiCl + Li3Po4 + 3LiPF6 and wherein the LiPF6 is isolated from the reaction mixture in the form of a solution, where ethers, nitriles, esters, sulfones, carbonates, halogenated hydrocarbons and/or terti-ary amines are used as solvent.
This process employs raw materials which are offered on the market as inexpensive products, and which are mostly avail-able in a very pure form- The use of pure LiF is very advan-tageous, but it is also possible to use LiF contaminated with minor amounts of other alkali and alkaline earth fluorides.
The chemical reactions utilized for the inventive process supply the end product LiPF6 in a high yield, where the other reaction products can easily be separated and recovered. The solvents required for performing the process in accordance with the invention, which solvents must be acid-free and aprotic, are available in a high purity and can be recovered CA 022~998~ 1999-01-07 .
and purified by means of simple methods. The required reac-tion times and reaction temperatures are easy to control on a technical scale even in the presence of the raw materials re-quired for the execution of the process, as corresponding re-actors are nowadays provided by the process technology. It is possible to also use PBrs and POBr3 instead of PC15 and POCl3 for performing the inventive process, but it turned out that these bromium compounds are very expensive and hardly avail-able on the market. Therefore, PBrs and POBr3 are not suited for performing the inventive process on a technical scale.
In the process in accordance with the invention diethyl ether is preferably used as solvent, as LiPF6 is particularly eas-ily soluble in diethyl ether.
In the process in accordance with the invention, the reaction times are shortened and/or the yields are increased, when an excess of 0.1 to 2 mol LiF, based on 1 mol PC15 and POCl3, is present.
The process in accordance with the invention can on the one hand be performed such that the reaction is first of all ef-fected for 0.1 to 5 hours at 150 to 300~C and subsequently for 0.1 to 5 hours at 60 to 120~C, and that the LiPF6 is then extracted from the solid reaction mixture by means of the solvent at 0 to 80~C. This procedure is performed in a closed reactor under the pressure caused by the starting substances and the reaction temperature. At 150 to 300~C PF5 is probably formed in situ and subsequently reacts with LiF to form the end product at 60 to 120~C. During the extraction of the cooled, solid reaction mixture by means of a solvent, the end product goes into solution and can be filtered off the solid reaction residue. The residue consists of LiCl, LiF and pos-sibly lithium phosphate, which can be processed according to known methods. The solvent used for extraction can be puri-fied by distillation or again be utilized for extraction.
.
CA 022~998~ 1999-01-07 To be able to utilize the inexpensive raw material PCl3 for the inventive process, it is provided in accordance with the invention that PCls and POC13 are produced in situ from PC13 during the reaction stage taking place at 150 to 300~C corre-sponding to the chemical equations c) PC13 + Cl2 - > PCl5 d) 2PC13 + ~2 - > 2POC13.
It is quite obvious for the man skilled in that art that the execution of the inventive process corresponding to the gas-solids reaction is not impaired by the presence of chlorine and oxygen.
The process in accordance with the invention can on the other hand be performed such that the reaction is effected for 0.1 to 5 hours at -20 to 100~C in the presence of the solvent, and that the solution containing LiPF6 is filtered off the insoluble reaction products.
What is particularly advantageous in this alternative proce-dure is the fact that relatively low reaction temperatures can be employed, where reaction temperatures of 0 to 80~C are preferred in accordance with the invention. Moreover, the re-action in the solvent takes place with a good yield, the LiPF6 is easily soluble in the solvent, and the other reac-tion products can be separated in solid form by means of fil-tration. The PCls can advantageously be reacted with LiF in the solvents diethyl ether as well as dimethyl, ethylene and propylene carbonate, whereas the solvents acetonitrile, tet-rahydrofuran and methyltetrahydrofuran turned out to be par-ticularly useful for reacting POC13 with LiF.
In accordance with the invention it is provided that before or during the reaction taking place in the solvent the PCl5 CA 022~998~ 1999-01-07 is produced by chlorinating PC13 in the presence of the sol-vent at -20 to 100~C according to the equation e) PCl3 + Cl2 -> PCl5.
In this way, the inexpensive raw material PC13 is also avail-able for the variant of the inventive process which is per-formed at -20 to 100~C in the presence of a solvent. The chlorination of PC13 is highly exothermal (~H = 125kJ/mol).
The economy of the inventive process can be improved in that the solvent contains 5 to 50 wt-% liquid, aliphatic or aro-matic hydrocarbons. This measure does not negatively influ-ence the solubility of the process product LiPF6; however, the use of inexpensive, liquid hydrocarbons leads to a reduc-tion of the process costs.
Finally, it is provided in accordance with the invention that the LiPF6 is obtained from the solution containing LiPF6 in crystalline form by evaporating the solvent. The separation of the solvent from the process product by distillation is advantageously promoted by an inert gas stream and/or by means of a distillation under a reduced pressure. It was noted that the used organic solvents can be removed from the process product much easier and with less residues than HF.
When performing the inventive process it should of course be made sure that no water is present in the individual reac-tions. The used solvents should almost be anhydrous. It has turned out that the raw materials provided for the execution of the inventive process are in any case easier to handle than gaseous PFs. The LiF is used in a finely crystalline form. In the gas-solids reactions belonging to the inventive process and in the reactions taking place in a liquid phase, very little or no PFs was identified in the reaction mixtures upon completion of the reaction; it is, however, assumed that .
CA 022~998~ 1999-01-07 PF5 is formed in situ in the individual reactions and is then decomposed immediately. The reaction time of the inventive reactions can be shortened by stirring or grindingly stir-ring. The reaction of LiF with POC13 performed in a solvent should take place in a closed, pressure-tight reactor, in or-der to avoid that the POF3 formed intermediately escapes from the reactor uncontrolled. The relatively low pressures occur-ring here are easy to control.
The processing of the residue obtained in the individual re-actions, which contains LiCl or LiCl and Li3Po4 as well as excess LiF, iS effected such that the residue is treated with water. LiF and Li3P04 are obtained in insoluble form. If PCl5 is used as raw material, the insoluble residue exclusively consisting of LiF can again be used as raw material for the inventive process upon filtering and drying the same. When treated with water, LiCl goes into solution and can be recov-ered from the aqueous solution and be reused in some other way.
It is known that the process product LiPF6 forms addition products with water, so that the suitability of this sub-stance, in particular as electrolyte for batteries, is re-stricted. For removing residual traces of water, which get into the reaction system in particular by the used raw mate-rials, it is provided that the solutions of LiPF6 produced in accordance with the inventive process are reacted with or-ganolithium compounds, in particular methyllithium or butyl-lithium, or with lithium hydride, before further processing the same. Together with water, these compounds form lithium hydroxide as well as hydrocarbons such as methane or butane and hydrogen. The lithium hydroxide can be filtered off, whereas the hydrocarbons or the hydrogen escape from the so-lution as gases. However, the water content of the product solutions is small in any case, as LiCl, which is formed in the inventive process, is hygroscopic and therefore already .
CA 022~998~ 1999-01-07 largely binds the water contained in the solutions. The dry-ing effect of the LiCl provides for the use of solvents which need not be anhydrous quantitatively, which advantageously reduces the costs for the dehydration of the solvent.
Purifying the LiPF6 may be effected by recrystallizing in the solvent, as the product is easily soluble in the solvent at an elevated temperature and less easily soluble at a lower temperature. Diethyl ether is particularly useful as solvent and suited for recrystallizing the LiPF6, where the LiPF6 is dissolved at 30 to 40~C and recrystallized at 0 to 10~C. The product produced in accordance with the inventive process in any case has a purity > 99.0 % and in general even a purity > 99.8 %. The product is virtually anhydrous; the product-containing solutions obtained after the extraction or filtra-tion still have a water content < 10 ppm (determined accord-ing to K. Fischer). The process product is marketed either in the form of solutions or in solid form.
In the gas-solids reactions, the product yield generally is 80 to 95 % after the extraction, and in the reactions per-formed in a solvent the yield is 90 to 96 % after the filtra-tion.
The subject-matter of the invention will subsequently be ex-plained in detail with reference to embodiments.
Example 1 500 g (2.4 mol~ PCls (purity 99 %) and 448 g (17.3 mol) dried LiF were filled into a stainless steel autoclave and heated to 300~C within one hour by stirring. This temperature was maintained for about one hour- There was achieved an autoge-nous pressure of 55 bar. Then, the temperature was decreased to about 80~C, and stirring was effected at this temperature . .
- CA 022~998~ 1999-01-07 for 3 hours. Upon cooling to room temperature, a final pres-sure of about 5 bar was achieved.
The gaseous reaction products were absorbed in sodium hydrox-ide solution. They contained about 1 % of the used phosphorus as volatile halogen compounds- The white, finely powdered residue was filled into a glass apparatus under an inert gas, mixed with 1500 ml diethyl ether and stirred for about 30 minutes. The insoluble constituents (573.4 g, consisting of a mixture of LiCl and LiF) were filtered off via a fritted-glass filter (G3) and rinsed three times with about 200 ml diethyl ether. The water content in the combined filtrates was < 10 ppm (Karl Fischer titration). A lP-NMR spectrum ex-clusively revealed a signal at -143.5 ppm (septet) for the formed PF6. Upon separation of the diethyl ether 335 g (yield 91.9 %) finely powdered LiPF6 were left. The product con-tained 0.2 % chloride and had a purity of about 99.8 %.
Example 2 To 8.04 g (0.31 mol) dried LiF, suspended in 80 ml commer-cially available propylene carbonate (purity 99 %) 8.97 g (0.043 mol) PCls were added within about 15 minutes. The tem-perature of the reaction mixture increased from 20 to about 32~C. After stirring for one hour at room temperature, the reaction was completed ( P-NMR spectrum only revealed a sig-nal at -143.5 ppm). The filtered solution (90.8 g) had a wa-ter content < 10 ppm and contained 6.2 g LiPF6 (yield 86.1 %). By rinsing the precipitate with propylene carbonate the yield could be increased to 90 %.
Example 3 In a double-walled reactor 117.5 g (0,56 mol) PCls were added to a suspension of 96.7 g (3.73 mol) LiF in 480 ml diethyl ether at a reaction temperature of 20OC within about 30 min-CA 022~998~ 1999-01-07 utes. By means of cooling, the temperature was maintained at 22~C. Subsequently, stirring was effected for about one hour at 20~C, and the reaction solution was liberated from insolu-ble constituents (127.1 g, mixture of LiCl and LiF) by fil-tering the same. The filtration residue was rinsed three times with 50 ml diethyl ether each- The solvent was con-densed off the combined filtrates, and the residue was dried in a vacuum until the weight remained constant. There were left 82.0 g (yield 95.7 %) pure LiPF6.
Example 4 27.7 g (0.2 mol) PC13 were dissolved in 99 g methylene chlo-ride. Into this solution, dried chlorine was introduced at 20 to 30~C by cooling the same- The chlorination of PC13 took place exothermally and was terminated when no further reac-tion heat was observed. The PCls formed was contained in methylene chloride partly in dissolved form and partly in suspended form. Excess chlorine was washed out of the suspen-sion with a dried stream of nitrogen. Subsequently, the sus-pension was diluted with 105.5 g diethyl ether and then charged with 37.4 g (1.44 mol) LiF for a period of 50 min-utes. The exothermal reaction of PCls with LiF started imme-diately and was maintained at 20 to 28~C by means of cooling.
When the entire amount of LiF had been introduced into the suspension, stirring was continued for two hours. Then, the solids were filtered off, the solvent was distilled off the filtrate, and the remaining LiPF6 was purified by recrystal-lizing the same in diethyl ether- The yield was 83 %, based on PCl3.
Example 5 In an autoclave, 8.65 g POC13 (65.4 mmol) and 9.8 g (370 mmol) finely divided, dry LiF were mixed with 50 ml tetrahy-drofuran. The mixture was grindingly stirred for 9 hours at .__ CA 022~998~ 1999-01-07 25~C, where an excess pressure of about 0.1 bar was produced.
Upon cooling, the autoclave was relieved, and the reaction mixture was filtered- In the filtrate, no POC13 could be de-tected. The tetrahydrofuran was filtered off the filtrate in a vacuum, and the LiPF6 was left as product, which was puri-fied by recrystallizing the same with diethyl ether.
Claims (11)
1. A process of producing LiPF6, characterized in that LiF
is reacted with PCl5 or POCl3 to form LiPF6 at a reaction temperature of -20 to 300°C for a reaction time of 0.1 to 10 hours corresponding to the chemical equations a) PCl5 + 6LiF ~ 5LiCl + LiPF6 b) 4POCl3 + 18LiF ~ 12LiCl + Li3PO4 + 3LiPF6 and in that the LiPF6 is isolated from the reaction mixture in the form of a solution, where ethers, nitriles, esters, sulfones, carbonates, halogenated hydrocarbons and/or tertiary amines are used as solvent.
is reacted with PCl5 or POCl3 to form LiPF6 at a reaction temperature of -20 to 300°C for a reaction time of 0.1 to 10 hours corresponding to the chemical equations a) PCl5 + 6LiF ~ 5LiCl + LiPF6 b) 4POCl3 + 18LiF ~ 12LiCl + Li3PO4 + 3LiPF6 and in that the LiPF6 is isolated from the reaction mixture in the form of a solution, where ethers, nitriles, esters, sulfones, carbonates, halogenated hydrocarbons and/or tertiary amines are used as solvent.
2. The process as claimed in claim 1, characterized in that diethyl ether is used as solvent.
3. The process as claimed in claims 1 to 2, characterized in that an excess of 0.1 to 2 mol LiF is present.
4. The process as claimed in claims 1 to 3, characterized in that the reaction is first of all effected for 0.1 to 5 hours at 150 to 300°C and subsequently for 0.1 to 5 hours at 60 to 120°C, and that the LiPF6 is then extracted from the solid reaction mixture by means of the solvent at 0 to 80°C.
5. The process as claimed in claim 4, characterized in that PCl5 and POCl3 are produced in situ from PCl3 during the reaction stage taking place at 150 to 300°C corresponding to the chemical equations c) PCl3 + Cl2 ~ PCl5 d) 2PCl3 + O2 ~ 2POCl3.
6. The process as claimed in claims 1 to 3, characterized in that the reaction is effected for 0.1 to 5 hours at -20 to 100°C in the presence of the solvent, and that the solution containing LiPF6 is filtered off the insoluble reaction products.
7. The process as claimed in claim 6, characterized in that the reaction is effected in the presence of the solvent at 0 to 80°C.
8. The process as claimed in claims 6 and 7, characterized in that before or during the reaction taking place in the solvent, the PCl5 is produced by chlorinating PCl3 in the presence of the solvent at -20 to 100°C according to the equation e) PCl3 + Cl2 ~ PCl5.
9. The process as claimed in claims 1 to 8, characterized in that the solvent contains 5 to 50 wt-% liquid, aliphatic or aromatic hydrocarbons.
10. The process as claimed in claims 1 to 9, characterized in that the LiPF6 is obtained in crystalline form from the solution containing LiPF6 by evaporating the solvent.
11. The process as claimed in claims 1 to 10, characterized in that the solution containing LiPF6 is dried before processing the same by reaction with organolithium compounds, in particular methyllithium or butyllithium, or with lithium hydride.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19632543A DE19632543C1 (en) | 1996-08-13 | 1996-08-13 | Process for the production of LiPF¶6¶ |
| DE19632543.9 | 1996-08-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2259985A1 true CA2259985A1 (en) | 1998-02-19 |
Family
ID=7802474
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002259985A Abandoned CA2259985A1 (en) | 1996-08-13 | 1997-08-11 | Lipf6 production process |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0944550A1 (en) |
| JP (1) | JP2001500834A (en) |
| KR (1) | KR20000016746A (en) |
| CA (1) | CA2259985A1 (en) |
| DE (1) | DE19632543C1 (en) |
| WO (1) | WO1998006666A1 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2581980A1 (en) * | 2010-06-08 | 2013-04-17 | Central Glass Company, Limited | Method for producing electrolyte solution for lithium ion battery, and lithium ion battery using the electrolyte solution |
| CN103964409B (en) * | 2013-02-05 | 2018-04-10 | 关东电化工业株式会社 | High-purity LiPF6Manufacture method |
| CN108439362A (en) * | 2018-05-18 | 2018-08-24 | 青海聚之源新材料有限公司 | A kind of preparation method of high-end lithium hexafluoro phosphate |
| CN109019550A (en) * | 2018-10-16 | 2018-12-18 | 河南工程学院 | A kind of method that organic solvent prepares lithium hexafluoro phosphate |
| CN110817831A (en) * | 2019-11-25 | 2020-02-21 | 湖北迈可凯科技有限公司 | Continuous synthesis method and device of lithium hexafluorophosphate |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19805356C1 (en) * | 1998-02-12 | 1999-06-17 | Metallgesellschaft Ag | Lithium hexafluorophosphate is produced by reacting phosphorus pentachloride with an acidified lithium fluoride-diethylether suspension |
| DE19805360C1 (en) * | 1998-02-12 | 1999-06-17 | Metallgesellschaft Ag | Coarse pure lithium hexafluorophosphate crystals are produced using an aprotic crystallization aid |
| DE19824984A1 (en) * | 1998-06-04 | 1999-12-09 | Basf Ag | Process for the crystallization of high-purity LiPF¶6¶ from organic solvents |
| JP4047817B2 (en) * | 2002-03-21 | 2008-02-13 | カウンシル・オブ・サイエンティフィック・アンド・インダストリアル・リサーチ | Synthesis of lithium hexafluorophosphate by solid-state heating reaction |
| WO2007066464A1 (en) * | 2005-12-06 | 2007-06-14 | Central Glass Company, Limited | Method for producing electrolyte solution for lithium ion battery and lithium ion battery using same |
| JP4215078B2 (en) | 2006-07-21 | 2009-01-28 | ソニー株式会社 | Positive electrode for non-aqueous electrolyte battery and non-aqueous electrolyte battery |
| CN103213963B (en) * | 2012-01-18 | 2016-02-24 | 彭国启 | A kind of direct method preparing liquid lithium hexafluorophosphate |
| KR102036924B1 (en) * | 2019-03-15 | 2019-10-25 | (주)후성 | Method for producing alkali metal hexafluorophosphate, alkali metal hexafluorophosphate, method for producing electrolyte concentrate comprising alkali metal hexafluorophosphate, and method for producing secondary battery |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3907977A (en) * | 1969-05-29 | 1975-09-23 | United States Steel Corp | Method for the preparation of high purity, highly surface active LiAsF{HD 6 |
| US3607020A (en) * | 1970-03-19 | 1971-09-21 | Foote Mineral Co | Preparation of lithium hexafluorophosphate |
| IL41154A0 (en) * | 1971-12-27 | 1973-02-28 | Gte Laboratories Inc | Electrochemical cell |
| JPS60251109A (en) * | 1984-05-28 | 1985-12-11 | Daikin Ind Ltd | Manufacture of lithium hexafluorophosphate |
| JP2987713B2 (en) * | 1990-11-09 | 1999-12-06 | 株式会社トーケムプロダクツ | Method for producing high-purity hexafluorophosphoric acid compound |
| JPH05279003A (en) * | 1992-03-31 | 1993-10-26 | Morita Kagaku Kogyo Kk | Production of lithium hexafluorophosphate |
-
1996
- 1996-08-13 DE DE19632543A patent/DE19632543C1/en not_active Expired - Fee Related
-
1997
- 1997-08-11 CA CA002259985A patent/CA2259985A1/en not_active Abandoned
- 1997-08-11 WO PCT/EP1997/004359 patent/WO1998006666A1/en not_active Application Discontinuation
- 1997-08-11 JP JP10509396A patent/JP2001500834A/en active Pending
- 1997-08-11 EP EP97941932A patent/EP0944550A1/en not_active Ceased
- 1997-08-11 KR KR1019980710353A patent/KR20000016746A/en not_active Application Discontinuation
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2581980A1 (en) * | 2010-06-08 | 2013-04-17 | Central Glass Company, Limited | Method for producing electrolyte solution for lithium ion battery, and lithium ion battery using the electrolyte solution |
| EP2581980A4 (en) * | 2010-06-08 | 2014-07-09 | Central Glass Co Ltd | Method for producing electrolyte solution for lithium ion battery, and lithium ion battery using the electrolyte solution |
| CN103964409B (en) * | 2013-02-05 | 2018-04-10 | 关东电化工业株式会社 | High-purity LiPF6Manufacture method |
| CN108439362A (en) * | 2018-05-18 | 2018-08-24 | 青海聚之源新材料有限公司 | A kind of preparation method of high-end lithium hexafluoro phosphate |
| CN109019550A (en) * | 2018-10-16 | 2018-12-18 | 河南工程学院 | A kind of method that organic solvent prepares lithium hexafluoro phosphate |
| CN110817831A (en) * | 2019-11-25 | 2020-02-21 | 湖北迈可凯科技有限公司 | Continuous synthesis method and device of lithium hexafluorophosphate |
Also Published As
| Publication number | Publication date |
|---|---|
| DE19632543C1 (en) | 1998-04-02 |
| KR20000016746A (en) | 2000-03-25 |
| JP2001500834A (en) | 2001-01-23 |
| WO1998006666A1 (en) | 1998-02-19 |
| EP0944550A1 (en) | 1999-09-29 |
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