TW201318972A - Manufacture of mixtures comprising LiPO2F2 and LiPF6 - Google Patents

Abstract

Mixtures comprising LiPO2F2 and LiPF6 both of which are electrolyte salts or additive for, i.a., Li ion batteries, are manufactured by the reaction of POF3 and LiF. The mixtures can be extracted with suitable solvents to provide solutions containing LiPO2F2 and LiPF6 which can be applied for the manufacture of Li ion batteries, Li-air batteries and Li-sulfur batteries. Equimolar mixtures comprising LiPO2F2 and LiPF6 are also described, as well as a method for the manufacture of electrolyte compositions obtained by the extraction of equimolar mixtures comprising LiPO2F2 and LiPF6.

Description

Manufacture of a mixture containing LiPO 2 F 2 and LiPF 6

The present application claims priority to the European Patent Application No. EP 1 117 771 8.1 filed on Aug. 16, 2011, the entire content of which is hereby incorporated by reference.

The present invention relates to a process for producing a mixture comprising LiPO ₂ F ₂ and LiPF ₆ comprising a step of reacting phosphonium fluoride (POF ₃ ) with lithium fluoride (LiF). The invention is also directed to solid LiPO ₂ F ₂ in the form of a needle.

Lithium difluorophosphate, LiPO ₂ F ₂ , is useful as an electrolyte salt for an electrolyte composition further containing LiPF ₆ . Thus, EP-A-2 065 339 discloses how to make a mixture of LiPF ₆ and LiPO ₂ F ₂ with a halide other than fluoride, LiPF ₆ and water. The resulting salt mixture, dissolved in an aprotic solvent, was used as an electrolyte solution for a lithium ion battery. EP-A-2 061 115 describes the production of LiPO ₂ F ₂ with a compound of P ₂ O ₃ F ₄ and Li; and the manufacture of LiPO with LiPF ₆ and a compound having a Si—O—Si bond, such as a decane. ₂ F ₂ . US 2008-305402 and US 2008/102376 disclose the production of LiPO ₂ F ₂ by LiPF ₆ from a carbonate compound; according to US 2008/102376, LiPF ₆ decomposes at 50 ° C and higher to form PF ₅ ; It is disclosed that PF ₅ is formed only at temperatures at and above the melting point of LiPF ₆ (about 190 ° C).

However, the above method is technically difficult, and the starting material LiPF ₆ is expensive, and thus it is used to increase the production cost. Since LiPF ₆ is used as an electrolyte salt together with LiPO ₂ F ₂ , this is ineffective for producing LiPO ₂ F ₂ system at the cost of LiPF ₆ . What is often desired is a method for producing both LiPO ₂ F ₂ and LiPF ₆ . Therefore, there is a need to develop new methods that avoid the disadvantages noted above.

The object of the present invention is to provide LiPO ₂ F ₂ together with LiPF ₆ in a technically feasible and economical manner. Another object of the invention is to provide a path for a solution containing both LiPF ₆ and LiPO ₂ F ₂ in a simpler manner. These and other objects are achieved by the present invention as outlined in the patent application.

According to an aspect of the invention, a method of the invention for producing a mixture comprising LiPO ₂ F ₂ and LiPF _{6 in} an approximate equimolar amount comprises a step of reacting LiF with POF ₃ .

LiF is a relatively inexpensive, easy to purify starting material which is commercially available, for example, from Chemetall GmbH, Germany. Phosphonium fluoride (POF ₃ ) is commercially available, for example, from ABCR GmbH & Co. KG. If desired, POF ₃ can be made with POCl ₃ and a fluorinating agent such as HF, ZnF ₂ or amine-HF. The produced POF ₃ can be purified by distillation. The reaction equation is 2POF ₃ + 2LiF → LiPO ₂ F ₂ + LiPF ₆ (I).

Therefore, two valuable products are produced according to the reaction of equation (I). A technical advantage is that LiF can be easily dried, which reduces the risk of hydrolysis of LiPF ₆ , especially.

The method may further comprise the steps of, for example, a step for providing a solution containing LiPO ₂ F ₂ and LiPF ₆ , one or more steps for obtaining purified LiPO ₂ F ₂ as described below, and other steps.

The reaction of the present invention can be carried out by gas-solid reaction by passing POF ₃ through a LiF bed or by reacting the two components in a high pressure valve. If desired, the LiF may be suspended in an aprotic organic solvent, and/or the POF ₃ may be introduced and dissolved in an aprotic organic solvent, and thus, in this case, a gas-liquid-solid reaction is carried out. Or a liquid-solid reaction. Suitable solvents for POF ₃ are, for example, hydrazine compounds, such as diethyl ether, and organic solvents useful as solvents in lithium ion batteries; many examples of such solvents are given below, such as, in particular, organic carbonates, but also within Esters, formamide, pyrrolidone, oxazolidinone, nitroalkane, N,N-substituted urethane, cyclobutyl hydrazine, dialkyl hydrazine, dialkyl sulfite, acetate, Nitrile, acetamide, glycol ether, dioxolane, dialkoxyethane, trifluoroacetamide.

In other embodiments, the POF ₃ in the form of complexes, in particular in a donor - acceptor complexes form (e.g. POF ₃ - amine complexes) introduced into the reactor. Those complexes comprising: POF ₃ - pyridine, POF ₃ - triethylamine, POF ₃ - tributylamine, POF ₃ -DMAP (4- (dimethylamino) pyridine), POF ₃ -DBN (1,5- Diazabicyclo[4.3.0]non-5-ene), POF ₃ -DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), and POF ₃ -methyl Imidazole. In a specific embodiment, a separate container can be used to supply POF ₃ to the reactor vessel. Preferably, POF ₃ is introduced into the reactor as a gas.

Preferably, the reaction is carried out in the absence of water or moisture. As mentioned above, LiF can be dried prior to introduction into the reaction. Alternatively or additionally, the reaction can be carried out in the presence of an inert gas for at least a portion of its duration; dry nitrogen is very suitable, but other dry inert gases are also applicable. The reaction can be carried out in an autoclave type vessel or in other reactors. Preferably, the reaction is carried out in an apparatus made of steel or other corrosion resistant material, such as in a reactor made of or coated with Monel metal.

LiF is preferably applied in the form of small particles, for example in the form of a powder.

Preferably, no HF is added to the reaction mixture. Preferably, no difluorophosphoric acid is added to the reaction mixture. Preferably, it is equal to or greater than 80%, more preferably equal to or greater than 85%, and preferably 100% of the P content is derived from the POF in the mixture of LiPO ₂ F ₂ and LiPF ₆ produced. ₃ .

The molar ratio of POF ₃ to LiF is ideally 1:1. A preferred minimum ratio of POF ₃ to LiF is 0.9:1. If lower, the yield is correspondingly lower and unreacted LiF will be present in the resulting reaction mixture. Preferably, POF ₃ and LiF are more than or equal to 1:1. Preferably, it is equal to or less than 5:1, more preferably equal to or less than 2:1. It can be even larger than 5:1, but a large amount of POF _{3 is} lost, or it must be reused, which requires additional device parts and consumes energy.

The reaction time is chosen such that the desired degree of conversion is achieved. Frequently, a reaction time of 1 second to 5 hours gives a good reaction result. A preferred reaction time of 0.5 to 2 hours, and an optimum reaction time of about 1 hour gives good results. The reaction rate is very fast.

Preferably, the reaction temperature is equal to or higher than 0 °C. Preferably, the reaction temperature is equal to or lower than 100 °C.

The reaction temperature is preferably equal to or higher than the ambient temperature (25 ° C), and more preferably equal to or higher than 40 ° C. The reaction temperature is preferably equal to or lower than 90 ° C, more preferably equal to or lower than 70 ° C. The preferred temperature range for the reaction is carried out at a temperature of from 25 ° C to 90 ° C, especially from 40 ° C to 70 ° C.

If desired, a reactor can be applied with an internal heating or cooling device or an external heating or cooling device. It may have, for example, a line or conduit with a heat transfer reagent such as water.

The reaction between POF ₃ and LiF can be carried out at ambient pressure (1 bar absolute). Preferably, the reaction is carried out at a pressure above 1 bar (absolute) and more preferably at a pressure above 3 bar (absolute). Preferably, the pressure system is equal to or less than 10 bar (absolute value) and more preferably it is equal to or less than 5 bar (absolute value). As the reaction progresses, the POF ₃ is consumed, and the pressure is thus lowered, for example, in the autoclave. If POF ₃ is continuously introduced into the reaction, a decrease in pressure indicates that the reaction is still proceeding.

The reaction of POF ₃ with LF can be carried out in batches, for example in an autoclave. The reactor can have a variety of internal devices, such as agitators, to provide mechanical impact on the surface of the LiF solid particles to remove reaction products from the surface and provide an unreacted fresh surface. It is also possible to shake or rotate the reactor itself.

Alternatively, the reaction can be carried out continuously, for example in a flow reactor. For example, LiF can be provided in the form of a bed; POF ₃ can pass through the bed until a "penetration" of POF ₃ is observed, which indicates the end of the reaction. If desired, a dry inert gas such as nitrogen or a rare gas may be passed through the LiF bed to remove oxygen, moisture or both prior to carrying out the reaction.

If the reaction is carried out continuously, for example, LiF can be maintained in the form of a bed in a flow reactor, for example as a fluidized bed, and POF _{3 is} continuously passed through the bed. POF ₃ and fresh LiF can be continuously introduced into the reactor, and the reaction product can be continuously withdrawn from the reactor.

If it is desired to separate LiPO ₂ F ₂ and LiPF ₆ , the reaction can be carried out in an aprotic solvent since LiPF ₆ is much better soluble in these solvents than LiPO ₂ F ₂ ; LiPF ₆ is predominantly It is dissolved along with a small amount of LiPO ₂ F ₂ and can be removed in the solution. This solution containing dissolved LiPF ₆ and LiPO ₂ F ₂ is a valuable product as described below per se. The solid LiPO ₂ F ₂ forms a solid residue which can be purified as described below. Thus, the reaction between POF ₃ and LiF and the formation of LiPF ₆ (in the form of a valuable solution containing LiPF ₆ and LiPO ₂ F ₂ ) and a solid residue of LiPO ₂ F ₂ (this can be further purified) Subsequent separation can be carried out in the same reactor in a "one-pot" type.

If desired, a vacuum may be applied after the reaction is terminated, or a dry inert gas such as nitrogen or a rare gas may be passed through the formed LiPO ₂ F ₂ and LiPF ₆ to remove HF, moisture or solvent (if They are used) or residual POF ₃ .

If no solvent is used, the resulting reaction mixture contains approximately equal molar amounts of LiPO ₂ F ₂ and LiPF ₆ and is present as a solid. If desired, the solid can be comminuted (e.g., ground) to provide a larger contact surface if it is intended to dissolve its components.

Under "approximately equimolar amount" in the context the term "approximately" is represented by 40 mole% to 60 mole% of LiPO ₂ F _2, and 40 mole% to 60 mole% of LiPF ₆ composed LiPO ₂ A mixture of F ₂ and 1.2 LiPF ₆ , preferably from 45 mol % to 55 mol % of LiPO ₂ F ₂ and 45 mol % to 55 mol % of LiPF ₆ , more preferably 49 mol % A mixture of LiPO ₂ F ₂ and LiPF ₆ consisting of 51 mol% LiPO ₂ F ₂ and 49 mol% to 51 mol% LiPF ₆ .

The most reasonable way to work up the solid reaction mixture containing LiPO ₂ F ₂ and LiPF ₆ is to add an organic solvent, especially as an electrolyte for Li ion batteries, Li air batteries, and Li sulfur batteries. A solvent for the solution (when containing dissolved LiPF ₆ and LiPO ₂ F ₂ ). Many such solvents are given below. The most effective way is to apply an aprotic polar solvent that dissolves LiPF ₆ far better than LiPO ₂ F ₂ .

For applications where a molar mixture of LiPO ₂ F ₂ and LiPF ₆ can be applied, the reaction mixture can be applied without further processing; alternatively, any moisture, HF or residual POF ₃ can be removed by applying a vacuum if desired In the case of elevated temperatures, for example at temperatures above 100 ° C or even above 150 ° C, but preferably not above 200 ° C.

Considering that LiPF ₆ is generally used as an electrolyte salt in Li ion batteries, Li air batteries, and Li sulfur batteries, and LiPO ₂ F _{2 is} used as an additive of an electrolyte salt, in which LiPF ₆ is often dissolved to provide a 1 mol solution, and LiPO is to be ₂ F ₂ is dissolved in an amount to provide a concentration of 1% to 2% by weight. A preferred alternative to treating the reaction mixture is to extract the mixture using a solvent for a battery of the type mentioned. The concentration of LiPF ₆ in the extract is generally much higher than the concentration of LiPO ₂ F ₂ . This is very advantageous in the case where LiPF ₆ having a molar amount of 1 mol as mentioned above and together with 1 to 2% by weight of LiPO ₂ F ₂ , including LiPO ₂ is desired. F ₂ more electrolyte solution of LiPF ₆ . The actual concentration can be varied by adding LiPF ₆ , LiPO ₂ F ₂ and/or by adding a solvent or removing the solvent (for example by applying a vacuum).

Frequently, the aprotic organic solvent is selected from the group consisting of ketones; nitriles; formamides; dialkyl carbonates (straight chain) and carbonic acid esters (cyclic), and wherein the term "alkane" Preferred is a C1 to C4 alkyl group, and the term "alkylene group" preferably means a C2 to C7 alkylene group, including a vinyl group, wherein the alkyl group is preferably a bridge of 2 carbon atoms between the oxygen atoms of the -OC(O)-O- group; dimethylformamide, decylamine, such as N,N-dimethylacetamide, and N, N-diethylacetamide , acetone, acetonitrile, linear dialkyl carbonate such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, cyclic alkyl carbonate such as ethyl carbonate, propyl carbonate, and Carbonic acid extending vinyl ester is a suitable solvent.

Dimethyl carbonate and propylene carbonate are preferred solvents for use in the reaction mixture because LiPO ₂ F ₂ is at least quite soluble in such solvents which are very well suited for use in Li ion batteries. Other very suitable solvents are ethyl carbonate (EC), ethyl methyl carbonate (EMC), propyl carbonate, ethyl acetate, diethyl carbonate, dimethyl carbonate and propyl carbonate (PC). A mixture of acetonitrile, dimethoxyethane and acetone. The solubility of LiPO ₂ F ₂ in these solvents at ambient temperature is compiled in Table 1 below.

The solubility of LiPO ₂ F ₂ in acetonitrile and especially in dimethoxyethane and acetone is significantly higher; in the context of the present invention, such solvents provide solutions which also have LiPO ₂ F ₂ and LiPF ₆ ( Among them, a high concentration of LiPO ₂ F ₂ ) is useful. It has been pointed out that, however, acetone is not very well suited as a solvent for Li ion batteries.

The solubility of LiPO ₂ F ₂ in dimethoxyethane is even higher than in acetone. Dimethoxyethane is considered to be a solvent or solvent additive for Li-ion batteries. Therefore, dimethoxyethane can be used to provide a solution having a high concentration of both LiPF ₆ and LiPO ₂ F ₂ .

A solution of LiPF ₆ and LiPO ₂ F ₂ in dimethyl carbonate, propylene carbonate and mixtures thereof, which dissolves LiF which is at most negligible in magnitude, is particularly suitable for the manufacture of electrolytes for batteries.

In addition to the above-mentioned solvents, other solvents which are often used as electrolyte solvents for Li ion batteries can be used as a single solvent or as a component of a solvent mixture. For example, fluorinated solvents such as mono-, di-, tri-, and/or tetrafluoro-ethyl esters are very suitable. Other suitable solvent systems are: lactones, formamide, pyrrolidone, oxazolidinone, nitroalkane, N,N-substituted urethane, cyclobutane, dialkylarylene, dialkyl Sulfate (as described in M. Ue et al., J. Electrochem. Soc. [Electrochemicals] Vol. 141 (1994), pages 2989 to 2996), or trialkyl phosphate or alkane Oxy esters as described in DE-A 10016816.

Carbonic acid alkyl esters can be used as a solvent or solvent additive. Pyrocarbonates are also useful, see US-A 5,427,874. Alkyl acetates such as ethyl acetate, N,N-disubstituted acetamide, hydrazine, nitrile, glycol ethers and ethers are also useful, see EP-A-0 662 729. Mixtures of such solvents are often employed. Dioxolane is a useful solvent, see EP-A-0 385 724. For lithium bis-(trifluoromethanesulfonate) oxime, 1,2-bis-(trifluoroacetoxy)ethane and N,N-dimethyltrifluoroacetamide can be applied for dissolution. For the agent, see ITE Battery Letters Vol. 1 (1999), pp. 105-109. In the above, the term "alkyl" preferably denotes a saturated straight or branched C1 to C4 alkyl group; the term "alkylene" preferably denotes a C2 to C7 alkylene. a group comprising a vinyl group, wherein the alkyl group is preferably a bridge of 2 carbon atoms between the oxygen atoms of the -OC(O)-O- group, thereby Formed a 5-member ring.

Fluorine-substituted compounds are also suitable solvents for the dissolution of LiPO ₂ F ₂ or LiPF ₆ , such as fluorinated carbonates, which are selected from the group consisting of fluorine-substituted ethyl carbonates and fluorine substitutions. Dimethyl carbonate, fluorine-substituted ethyl methyl carbonate, and fluorine-substituted diethyl carbonate. They can be applied in the form of a mixture with a non-fluorinated solvent. For example, the non-fluorinated organic carbonates mentioned above are very suitable.

Preferred fluorine-substituted carbonates are: ethyl monofluorocarbonate, ethyl 4,4-difluorocarbonate, ethyl 4,5-difluorocarbonate, 4-fluoro-4-methyl Ethyl carbonate, 4,5-difluoro-4-methylcarbonate ethyl ester, 4-fluoro-5-methylcarbonate ethyl ester, 4,4-difluoro-5-methylcarbonate ethyl ester, 4-(fluoromethyl)-ethyl carbonate, 4-(difluoromethyl)-carbonic acid ethyl ester, 4-(trifluoromethyl)-carbonic acid ethyl ester, 4-(fluoromethyl)-4 - fluorocarbonic acid ethyl ester, 4-(fluoromethyl)-5-fluorocarbonic acid ethyl ester, 4-fluoro-4,5-dimethyl carbonate ethyl ester, 4,5-difluoro-4, 5-dimethyl carbonate ethyl ester, and 4,4-difluoro-5,5-dimethyl carbonate ethyl ester; dimethyl carbonate derivatives, including fluoromethyl methyl carbonate, difluorocarbonate Methyl ester, trifluoromethyl methyl carbonate, bis(fluoromethyl) carbonate, bis(difluoro)methyl carbonate, and bis(trifluoro)methyl carbonate; ethyl methyl carbonate Derivatives, including 2-fluoroethyl methyl carbonate, ethyl fluorocarbonate, 2,2-difluoroethyl methyl carbonate, 2-fluoroethylfluoromethyl carbonate, ethyl difluorocarbonate , 2,2,2-trifluoroethyl methyl carbonate, 2,2-difluoroethylfluoromethyl carbonate, 2-fluoroethyl difluoromethyl carbonate, and ethyl trifluoromethyl carbonate; and carbonic acid Derivatives of diethyl esters, including ethyl (2-fluoroethyl) carbonate, ethyl (2,2-difluoroethyl) carbonate, bis(2-fluoroethyl) carbonate, ethyl carbonate ( 2,2,2-trifluoroethyl)ester, 2,2-difluoroethyl 2'-fluoroethyl carbonate, bis(2,2-difluoroethyl) carbonate, carbonic acid 2,2,2 -Trifluoroethyl 2'-fluoroethyl ester, 2,2,2-trifluoroethyl 2',2'-difluoroethyl carbonate, and bis(2,2,2-trifluoroethyl carbonate) )ester.

It is also possible to use a carbonate having both an unsaturated bond and a fluorine atom (hereinafter abbreviated as "fluorinated unsaturated carbonate") as a solvent to dissolve a large amount of LiPF ₆ and a small amount of LiPO ₂ F ₂ . Such fluorinated unsaturated carbonates include any fluorinated unsaturated carbonate which does not significantly impair the advantages of the present invention.

Examples of the fluorinated unsaturated carbonate include a derivative of a fluorine-substituted carbonic acid vinyl ester, a fluorine-substituted ethylene carbonate derivative substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond, And a fluorine-substituted allyl carbonate.

Examples of the derivative of the carbonic acid vinyl ester include: fluorovinyl carbonate, 4-fluoro-5-methylvinyl carbonate, and 4-fluoro-5phenylvinyl carbonate.

Examples of derivatives of ethyl carbonate which are substituted by a substituent having an aromatic ring or a carbon-carbon unsaturated bond include 4-fluoro-4-vinyl carbonate Ester, 4-fluoro-5-vinyl carbonate ethyl ester, 4,4-difluoro-4-vinyl carbonate ethyl ester, 4,5-difluoro-4-vinyl carbonate ethyl ester, 4-fluoro -4,5-divinylcarbonate ethyl ester, 4,5-difluoro-4,5-divinylcarbonate ethyl ester, 4-fluoro-4-phenylcarbonic acid ethyl ester, 4-fluoro-5 -phenylphenyl carbonate, 4,4-difluoro-5-phenylethyl carbonate, 4,5-difluoro-4-phenylcarbonate ethyl ester and 4,5-difluoro-4,5 - Diphenyl carbonate extended ethyl ester.

Examples of the fluorine-substituted phenyl carbonate include fluoromethylphenyl carbonate, 2-fluoroethylphenyl carbonate, 2,2-difluoroethylphenyl carbonate, and 2,2,2-trifluorocarbonate. Ethyl phenyl ester.

Examples of the fluorine-substituted ethylene carbonate include: fluoromethyl vinyl carbonate, 2-fluoroethyl vinyl carbonate, 2,2-difluoroethyl vinyl carbonate, and 2,2,2-trifluoroethyl ethylene carbonate. ester.

Examples of the fluorine-substituted allyl carbonate include fluoromethylallyl carbonate, 2-fluoroethylallyl carbonate, 2,2-difluoroethylallyl carbonate, and 2,2,2-three carbonate. Fluoroethyl allyl ester.

The extraction of LiPF ₆ from LiPO ₂ F ₂ from a reaction mixture for providing a solution having a large amount of LiPF ₆ and a small amount of LiPO ₂ F ₂ can be carried out in a known manner, for example by directly reacting the reaction mixture in a reactor. The solvent (extractant) is stirred together or after being removed from the reactor and optionally comminuted or ground in a suitable container, such as a Soxhlet container. The extract includes the Li salts and can be further processed.

A liquid phase comprising a large amount of LiPF ₆ dissolved in the solvent and a small amount of LiPO ₂ F ₂ can be separated from the undissolved solid LiPO ₂ F ₂ in a known manner. For example, the solution can pass through a filter, or it can be decanted, or this separation can be accomplished by centrifugation.

If desired, high purity solid LiPO ₂ F ₂ can be recovered. For example, the residue containing the LiPO ₂ F ₂ solid is dissolved, and the corresponding solution may be cooled to precipitate the solid LiPO ₂ F ₂ , or a non-polar or organic liquid may be added to cause crystallization. For example, LiPO ₂ F ₂ can be dissolved in dimethoxyethane, and a hydrocarbon such as hexane can be added. LiPO ₂ F ₂ precipitates as a gelatinous solid. If acetone is used as the solvent, it is possible to obtain a 20% concentration of LiPO ₂ F ₂ . When cooled to 0 ° C, a solid, needle-like LiPO ₂ F ₂ precipitated.

Accordingly, the present invention provides a process for obtaining purified LiPO ₂ F ₂ wherein, in the first step, LiPF _{6 is} mainly extracted from the LiPO ₂ F ₂ -containing solution by using a solvent of mainly dissolved LiPF ₆ . Separating from the mixture with LiPF ₆ and a) dissolving the remaining undissolved LiPO ₂ F ₂ in a polar aprotic solvent until a saturation concentration of at least 90% is reached, cooling the solvent to precipitate LiPO ₂ F ₂ , The precipitated LiPO ₂ F ₂ is separated from the solvent and treated to remove any solvent, or b) the remaining undissolved LiPO ₂ F _{2 is} dissolved in a polar aprotic solvent, and a non-polar organic solvent is added to precipitate Dissolved LiPO ₂ F ₂ , the precipitated LiPO ₂ F ₂ is separated from the solvent and treated (eg, heated and/or vacuum applied) to remove any solvent.

Preferably, the solvent in step a) is acetone.

Preferably, wherein in step b), the aprotic solvent is dimethoxy The ethyl ethane, and the non-polar solvent is a hydrocarbon, preferably hexane.

If desired, LiPO ₂ F ₂ which is still undissolved in the reaction mixture may be stored or subjected to further purification treatment to obtain pure solid LiPO ₂ F ₂ , for example by dissolving in two as described above. In methoxyethane, acetone or solvent. The adhesion solvent can be removed by evaporation, and the evaporation can preferably be carried out in a vacuum depending on the boiling point of the or the binder solvent.

The dissolved LiPO ₂ F ₂ can be recovered from the solution by evaporating the solvent to obtain a pure solid LiPO ₂ F ₂ . This can be done in a known manner. For example, the adhesion solvent can be removed by evaporation, and such evaporation can preferably be carried out in a vacuum depending on the boiling point of the or the binder solvent.

The isolated solid LiPO ₂ F ₂ can be redissolved in any suitable solvent or solvent mixture. The solvents mentioned above, including acetone and dimethoxyethane, are very suitable. Since its main use is an additive for an electrolyte salt or a salt in the field of lithium ion batteries, it may preferably be dissolved in an anhydrous solvent for producing an electrolyte solution of a lithium ion battery. Such a solvent is disclosed above.

An equimolar mixture of LiPF ₆ and LiPO ₂ F ₂ can be obtained separately by separation from an inexpensive starting material by the process of the invention, both of which are valuable compounds and useful as a mixture (as described above) of). Pure needle-like LiPO ₂ F ₂ can be obtained from a concentrated solution of LiPO ₂ F ₂ in acetone and then cooled.

An advantage of using POF ₃ is that it can be prepared substantially without HCl in the chloro-fluorine exchange reaction. Due to the boiling point (bp) of POF ₃ , which is higher than HCl (the boiling point of HCl is -85.1 ° C), a simple distillation or condensation technique under pressure can be used for the purification of POF ₃ intermediates, which makes This method is more economical.

Another aspect of the invention relates to an equimolar mixture of LiPO ₂ F ₂ and LiPF ₆ . As indicated above, these mixtures are electrolyte solutions for electrolyte compositions of batteries and a valuable source for the manufacture of acicular LiPO ₂ F ₂ .

Still another aspect of the invention relates to needle-like solid LiPO ₂ F ₂ . The needles have a length to diameter ratio equal to or greater than three. LiPO ₂ F _{2 is} also a valuable product because it can be used as an additive for the battery electrolyte composition as mentioned above, and is in the form of a crystal which is easy to process.

In the event that any disclosure of patents, patent applications, and publications incorporated by reference is inconsistent with the present disclosure, and the extent of such conflicts renders the term unclear, the present description should be preferred.

The following examples are intended to describe the invention in more detail and are not intended to limit the invention.

Example 1: Making a molar mixture of LiPO ₂ F ₂ and LiPF ₆

225 g of LiF (supplier: Aldrich) was introduced into a mobile autoclave reactor and dried under vacuum (heat applied from the outside).

The closed reactor is activated and moved to mechanically affect the solid starting material and to improve the reaction, and the gaseous POF _{3 is} passed through a PTFE pipe from a gas bottle through the reactor. A pressure regulating valve. The rate of addition was limited by keeping the total reaction temperature (measured in the reactor) below 32 °C. The pressure does not rise until the end of the reaction due to the rapid reaction between LiF and POF ₃ . The average feed rate of 74 g/h of POF ₃ is possible while keeping the temperature inside the reactor below 32 °C.

After 9 hours, the pressure was raised to about 4 atmospheres and the system was maintained under these conditions for an additional two hours. After this time, the reactor was evacuated and heated from the outside until the internal temperature reached 70 ° C; the temperature was maintained at this level for 2.5 hours.

The product was removed from the reactor as a white powder to yield a total mass of 730 g (mass gain: 730 g - 225 g = 505 g: equal to 4.9 mol POF ₃ ).

For 225 g LiF (8.7 mol) theoretical amount POF ₃ (according to stoichiometry): 8.7 mol POF ₃ =905 g

The XRD of the product after the reaction is given in Table 1.

The peak indicated as a indicates LiPF ₆ ; the peak indicated as b indicates LiPO ₂ F ₂ ; the peak indicated as c indicates LiF.

LiPF ₆ shows 2-theta values at the following positions: 17; 19 (strong); 26 (strong); 29; 30; 40; 43; 45 and 54.

LiPO ₂ F ₂ shows the 2-theta value at the following position: 21.5 (strong); 22.0; 23.5; 27.0 (strong); 34.2; 43.2.

LiF shows 2-theta values at the following positions: 39 and 44 (weak).

Example 2: Production of acicular LiPO ₂ F ₂

The LiPO ₂ F ₂ powder obtained in Example 1 was dissolved in acetone to obtain a saturated solution. The solution was then cooled to 0 °C. LiPO ₂ F ₂ precipitates in the form of a needle.

Example 3: Electrolyte solution for lithium ion batteries, lithium-sulfur batteries, and lithium-oxygen batteries

The solid of Example 1 was extracted using a mixture of an equimolar volume of ethyl acetate ("EC") and propyl carbonate ("PP"), and the amount of the ethyl carbonate and propyl carbonate was mixed. This is such that a total volume of 1 liter is obtained. The resulting solution contained LiPF ₆ and additionally about 0.5% by weight of LiPO ₂ F ₂ .

Example 4: Electrolyte solution for lithium ion batteries, lithium-sulfur batteries, and lithium-oxygen batteries

The needles of Example 2 were dissolved in a mixture of equimolar volume of ethyl carbonate ("EC") and propylene carbonate ("PP") in a mixture such that a total volume of 1 liter was obtained. The resulting solution contained about 0.5% by weight of LiPO ₂ F ₂ .

1 shows a spectrum of XRD of a product obtained by reacting LiF with POF ₃ , having a peak "a" indicating LiPF _{6 ,} a peak "b" indicating LiPO ₂ F ₂ , and a peak "c" indicating LiF.

Claims (15)

A method for producing a mixture comprising LiPO ₂ F ₂ and LiPF ₆ comprising a step of reacting LiF with POF ₃ . The method of claim 1, wherein POF ₃ and LiF are reacted at a molar ratio of from 0.9:1 to 2:1. The method of claim 1, wherein the reaction time is from 0.5 to 2 hours. The method of claim 1, wherein the reaction is carried out at a temperature of from 25 ° C to 90 ° C. The method of claim 1, wherein the reaction is carried out at a pressure equal to or lower than 5 bar (absolute value). The method of claim 1, wherein the mixture containing LiPO ₂ F ₂ and LiPF ₆ is extracted using a solvent suitable as an electrolyte solvent for Li ion batteries, Li air batteries, and Li sulfur batteries. . The method of claim 6, wherein the solvent is selected from the group consisting of organic carbonates. The method of claim 1, wherein in the first step, LiPF _{6 is} mainly extracted from the mixture containing LiPO ₂ F ₂ and LiPF ₆ by extracting the mixture mainly with a solvent mainly dissolving LiPF ₆ . Separating, and a) dissolving the remaining undissolved LiPO ₂ F ₂ in a polar aprotic solvent until a saturation concentration of at least 90% is reached, cooling the solvent to precipitate LiPO ₂ F ₂ , the precipitated LiPO ₂ F ₂ is separated from the solvent and treated to remove any solvent, or b) the remaining undissolved LiPO ₂ F _{2 is} dissolved in a polar aprotic solvent, and a non-polar organic solvent is added to precipitate the dissolved LiPO ₂ F ₂ , the precipitated LiPO ₂ F ₂ was separated from the solvent and treated to remove residual solvent. The method of claim 8, wherein the solvent in the step a) is acetone. The method of claim 8, wherein in the step b), the aprotic solvent is dimethoxyethane, and the non-polar solvent is a hydrocarbon. An approximate isomer mixture consisting of LiPO ₂ F ₂ and LiPF ₆ . The patentable scope of the application mixture of 11 items, which by a line 40 mole% to 60 mole% of LiPO ₂ F _2, and 40 mole% to 60 mole% of the composition of LiPF _6. A solid needle-like LiPO ₂ F ₂ . A method of preparing a solution containing LiPO ₂ F ₂ and LiPF ₆ , wherein the approximate equimolar mixture consisting of LiPO ₂ F ₂ and LiPF ₆ as in claim 11 and at least one for Li ion battery The Li air battery and the solvent of the Li sulfur battery are in contact with each other. A Li ion battery, a Li air battery, or a Li sulfur battery containing an approximate molar mixture as in claim 11 of the patent application.