JP2019001700A - Method for producing lithium difluorophosphate using difluorophosphoric acid ester - Google Patents

Abstract

To provide a method of producing lithium difluorophosphate in a manner that is inexpensive and is industrially advantageous.SOLUTION: The present invention provides a method of producing lithium difluorophosphate for use as an additive applicable to the improvement of properties of non-aqueous electrolyte batteries in a manner that is inexpensive and is industrially advantageous. The lithium difluorophosphate is obtained from the reaction in a non-aqueous solvent between a difluorophosphoric acid ester given by fluorinating a dihalophosphoric acid ester, a lithium salt and water. The lithium difluorophosphate thus obtained can be used as an additive that improves properties of non-aqueous electrolyte batteries.SELECTED DRAWING: None

Description

  The present invention relates to a method for producing lithium difluorophosphate, and more particularly to a process for producing lithium difluorophosphate using a difluorophosphate ester, specifically, a method for producing lithium difluorophosphate for nonaqueous electrolyte batteries.

  In recent years, with the development of small storage products used in high energy density applications such as smartphones, mobile power supplies, tablet computers, etc., the production volume in the lithium battery industry has increased. At the same time, the use of lithium-ion batteries is no longer limited to consumer electronics, and two new application directions for power and energy storage have led to a vast market for lithium batteries, mainly in electric, hybrid and fuel cell vehicles. The focus is on mass storage systems suitable for power applications including auxiliary power supplies as well as electrical energy storage. Energy storage is also a driving force for growth, driven by policy promotion and the expansion of the operator network. Over the next few years, lithium-ion batteries will become a constantly expanding global industry.

Currently, with the expansion of the application field of lithium ion secondary batteries, there is an increasing demand for improving battery characteristics. Lithium difluorophosphate can significantly improve battery characteristics such as low-temperature characteristics, cycle characteristics, and storage characteristics of lithium ion secondary batteries as an additive to the electrolyte. For example, Japanese Patent Publication H11-067270 discloses a technology that employs a non-aqueous electrolyte containing at least one additive selected from lithium monofluorophosphate Li ₂ PO ₃ F and lithium difluorophosphate LiPO ₂ F _2. Have been described. In such a technique, the additive reacts with lithium to form a coating film at the interface between the positive electrode and the negative electrode, thereby preventing the electrolyte from being decomposed by contact with the positive electrode active material and the negative electrode active material. Therefore, self-discharge is suppressed and the storage characteristics after charging are improved. Japanese Patent No. 3439085 discloses that high-temperature cycle characteristics are improved by the effect of a film formed at the electrode interface by adding lithium difluorophosphate to the electrolyte.

According to conventional literatures or patents, the production method of difluorophosphate has problems such as difficulty in obtaining raw materials and difficulty in separation, and thus cannot satisfy the demand for large-scale industrial production. For example, in Japanese Unexamined Patent Application Publication No. 2014-62036, lithium difluorophosphate is produced by a method of mixing LiPF ₆ and LiCl and introducing water vapor. This method is not suitable for large-scale production because the raw material is inexpensive but the reaction is difficult to control, there are many by-products, and purification is difficult. International publication WO2012004187A2 provides a method for producing lithium difluorophosphate. In this method, LiHPO ₄ and HF are gas-solid reacted at 140 ° C. to form a mixture of lithium difluorophosphate, lithium monofluorophosphate and lithium fluoride, but separation of this mixture is difficult. International publication WO2012004188A1 provides another method for producing lithium difluorophosphate. In this method, P ₂ O ₅ and LiF are subjected to a solid-solid reaction at 300 ° C. to form a solid solution mixture of lithium difluorophosphate and lithium phosphate. Even if this mixture is pulverized and extracted for a long time, Only a small amount of lithium difluorophosphate can be separated.

  In contrast, the present invention is a novel process for producing lithium difluorophosphate using a difluorophosphate ester, and is a lithium difluorophosphate used as an additive that can be applied to improve the characteristics of a nonaqueous electrolyte battery. Is inexpensively and industrially advantageous. The lithium difluorophosphate is obtained by reacting a difluorophosphate obtained by fluorinating a dihalophosphate, a lithium salt, and water in a non-aqueous solvent, and thus obtained difluorophosphate Lithium can be used as an additive to improve the properties of the non-aqueous electrolyte battery.

  The present invention provides a method for producing lithium difluorophosphate using a difluorophosphate ester. In this method, a dihalophosphate compound is obtained by reacting a dihalophosphate compound with a fluorinating agent under the action of a catalyst to obtain a difluorophosphate compound, and the difluorophosphate compound and lithium salt obtained in step (1). And reacting water in a non-aqueous solvent to obtain lithium difluorophosphate (2).

The dihalophosphate compound is represented by the following formula (1).
In the formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br, and I, and R is a hydrocarbon group.

  As one embodiment of the present invention, the non-aqueous solvent is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether. , Ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole, and tetrahydrofuran.

  As one embodiment of the present invention, the lithium salt includes lithium chloride, lithium bromide, lithium fluoride, lithium iodide, lithium hydroxide, lithium carbonate, lithium bicarbonate, lithium phosphate, lithium dihydrogen phosphate, phosphorus One or more selected from the group consisting of dilithium oxyhydrogen, lithium metaphosphate, lithium acetate, and lithium sulfate.

  In one embodiment of the present invention, the molar ratio of the difluorophosphate ester, the lithium salt, and water is 1: 2: 2 to 1: 1: 0.01.

  In one embodiment of the present invention, the fluorinating agent is selected from the group consisting of potassium fluoride, sodium fluoride, cesium fluoride, triethylamine trihydrofluoride, pyridine hydrofluoride, and ammonium fluoride. Species or multiple species.

  As one embodiment of the present invention, the catalyst is one or more selected from the group consisting of a quaternary ammonium salt, a polyether, and a quaternary phosphonium salt.

  As one embodiment of the present invention, the above method for producing lithium difluorophosphate is carried out under protection of nitrogen gas.

  As one embodiment of the present invention, the reaction molar ratio of the dihalophosphate compound and the fluorinating agent is 1: (1-3).

  As one embodiment of the present invention, the ratio of the mass of the dihalophosphate compound to the volume of the non-aqueous solvent is (0.1 to 0.5): (1 to 5).

  As one embodiment of the present invention, the molar ratio of the dihalophosphate compound to the catalyst is 1: (0.01-1).

  The present invention has the following advantages over the prior art. That is, the dihalophosphate ester compound, the fluorinating agent, and the lithium salt, which are raw materials for the lithium difluorophosphate produced in the present invention, are readily available, and are either solid or liquid, so that the reaction operation is easy. The overall process is mild in conditions, simple in process, low in equipment and environmental requirements, high purity and good quality of the produced lithium difluorophosphate.

  The content of the present invention can be understood more easily by referring to the following details of preferred methods of carrying out the present invention and examples related thereto. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art, but if there is a conflict, follow the definitions in this specification.

  As used herein, the term “consisting of” has the same meaning as “containing”. As used herein, the terms “containing”, “including”, “having”, “comprising” or any variation thereof are intended to be included non-exclusively. For example, a composition, step, method, product or apparatus comprising the listed elements is not necessarily limited to these elements, but other elements not explicitly listed, or such compositions, steps, methods, products. Alternatively, device-specific elements may be included.

  The term “consisting of” is intended to exclude any element, step or ingredient not listed. When used in the claims, the claim is a closed claim and does not include materials other than those listed (except for normal impurities). The term “consisting of” does not limit the subject matter of the claim, but when used on a feature other than the subject, limits only the element relating to that feature, and no other element is excluded from the claim.

  Where equivalents, concentrations, or other values or parameters are shown as ranges, preferred ranges, or ranges limited by preferred values in a series of upper and lower limits, although the ranges are disclosed alone, It should be understood that all ranges formed by the upper limit or preferred value of any range and the lower limit or preferred value of any range are specifically disclosed. For example, when the range is “1-5”, the range is “1-4”, “1-3”, “1-2”, “1-2 and 4-5”, “1-3 and It should be understood that the range is such as “5”. Unless otherwise stated, ranges herein include the boundary values of the range and all integers and fractions within the range.

  The singular form also includes the plural subject unless the context clearly dictates otherwise. “Arbitrary” or “any one” means that such a matter or event may or may not occur, and includes situations where such an event occurs and situations where such an event does not occur.

  Approximate expressions modifying quantities in the description and in the claims are not intended to be limited to specific quantities, but amendments that result in acceptable and relevant basic functional changes that approach the quantities. Is included. Modifying a numerical value by “approximately”, “about”, etc. means that the present invention is not limited to the exact numerical value. In one example, the approximate term may correspond to the accuracy of the instrument that measures the numerical value. In this specification and in the claims, range limitations can be combined and / or interchanged, and unless otherwise specified, these ranges include all sub-ranges therein.

  Also, the terms “one” and “one” preceding an element or component of the present invention do not limit the quantity of the element or component. Thus, “one” or “one” should be understood to include one and at least one meaning. Unless expressly indicated otherwise in context, an element or component shown in the singular also includes the plural meanings.

  “Polymer” refers to a polymer produced by polymerizing monomers of the same or different types. The generic term “polymer” includes the terms “homopolymer”, “copolymer”, “terpolymer” and “copolymer”.

  “Copolymer” refers to a polymer produced by polymerizing at least two different monomers. The generic term “copolymer” refers to the terms “copolymer” (typically a polymer made with two different monomers) and “terpolymer” (typically a polymer made with three different monomers). including. Also included are polymers produced by polymerizing four or more monomers. “Blend” refers to a polymer formed by mixing two or more polymers by physical or chemical methods.

  The present invention provides a method for producing lithium difluorophosphate, which is technically easy to control, easy to obtain raw materials, low in cost, and high in product purity.

  The present invention provides a method for producing lithium difluorophosphate using a difluorophosphate ester. In this method, a dihalophosphate compound is obtained by reacting a dihalophosphate compound with a fluorinating agent under the action of a catalyst to obtain a difluorophosphate compound, and the difluorophosphate compound and lithium salt obtained in step (1). And reacting water in a non-aqueous solvent to obtain lithium difluorophosphate (2).

The dihalophosphate compound is represented by the following formula (1).
In the formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br, and I, and R is a hydrocarbon group.
The specific reaction formula is
RPO ₂ XY + MF → RPO ₂ F ₂ + MX + MY (reaction (2))

  In one embodiment of the present invention, R is a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a t-butyl group, a linear or branched group having 1 to 10 carbon atoms. It is one selected from the group consisting of alkanes, phenyl groups, benzyl groups and other substituted aromatic hydrocarbon groups.

  As one embodiment of the present invention, the MF is a fluorinating agent, and the fluorinating agent is potassium fluoride, sodium fluoride, cesium fluoride, triethylamine trihydrofluoride, pyridine hydrofluoride, fluorination. It is at least one selected from the group consisting of ammonium.

  In one embodiment of the present invention, the catalyst is at least one selected from the group consisting of a quaternary ammonium salt system, a polyether system, and a quaternary phosphonium salt system.

  As one embodiment of the present invention, the reaction solvent in the above step (2) is n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol. It is at least one selected from the group consisting of diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole and tetrahydrofuran.

  As an embodiment of the present invention, in reaction (2), the reaction molar ratio of the dihalophosphate compound to the fluorinating agent is 1: (1-3).

  As an embodiment of the present invention, in the reaction (2), the ratio (w / v) of the mass of the dihalophosphate compound to the volume of the nonaqueous solvent is (0.1 to 0.5): (1 to 5). ).

  As an embodiment of the present invention, in the reaction (2), the molar ratio of the dihalophosphate compound to the catalyst is 1: (0.01 to 1).

As an embodiment of the present invention, in the reaction (2), the reaction temperature at which the dihalophosphate compound RPO ₂ XY and the fluorinating agent MF generate the difluorophosphate compound RPO ₂ F ₂ is 20 to 200 ° C. The time is 1 to 24 hours.

The method for producing lithium difluorophosphate using a difluorophosphate compound is to directly produce lithium difluorophosphate by reacting a difluorophosphate compound, a lithium salt and water in a non-aqueous solvent. Is RPO ₂ F ₂ + LiZ + H ₂ O → LiPO ₂ F ₂ + HZ + ROH (reaction (3)).

  As one embodiment of the present invention, LiZ is a lithium salt, and is lithium chloride, lithium bromide, lithium fluoride, lithium iodide, lithium hydroxide, lithium carbonate, lithium bicarbonate, lithium phosphate, phosphoric acid. It is at least one selected from the group consisting of lithium dihydrogen, dilithium hydrogen phosphate, lithium metaphosphate, lithium acetate and lithium sulfate.

  As one embodiment of the present invention, the non-aqueous solvent is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether. , Diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole, and tetrahydrofuran.

  As an embodiment of the present invention, in the reaction (3), the reaction molar ratio of the difluorophosphate compound, the lithium salt, and water is 1: 2: 2 to 1: 1: 0.01.

  As an embodiment of the present invention, in the reaction (3), the ratio (w / v) between the mass of the difluorophosphate compound and the volume of the nonaqueous solvent is (0.1 to 0.5): (1 to 5).

As an embodiment of the present invention, in reaction (3), the reaction temperature at which the difluorophosphate compound RPO ₂ F ₂ and the lithium salt LiZ produce lithium difluorophosphate LiPO ₂ F ₂ is 0 to 80 ° C., and the reaction time is 1 to 24 hours.

  By further purifying the lithium difluorophosphate produced in the above reaction (2) and reaction (3), a high-quality lithium difluorophosphate product can be obtained.

  The present invention has the following advantages over the prior art. That is, the dihalophosphate ester compound, the fluorinating agent, and the lithium salt, which are raw materials for the lithium difluorophosphate produced in the present invention, are readily available, and are either solid or liquid, so that the reaction operation is easy. The overall process is mild in conditions, simple in process, low in equipment and environmental requirements, high purity and good quality of the produced lithium difluorophosphate.

Embodiment 1
The present invention provides a method for producing lithium difluorophosphate using a difluorophosphate ester. In this method, a dihalophosphate compound is obtained by reacting a dihalophosphate compound with a fluorinating agent under the action of a catalyst to obtain a difluorophosphate compound, and the difluorophosphate compound and lithium salt obtained in step (1). And reacting water in a non-aqueous solvent to obtain lithium difluorophosphate (2).

The dihalophosphate compound is represented by the following formula (1).
In the formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br, and I, and R is a hydrocarbon group.

Embodiment 2
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the non-aqueous solvent is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane, cyclohexane, n- One or more selected from the group consisting of heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole and tetrahydrofuran It is a seed.

Embodiment 3
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the lithium salt includes lithium chloride, lithium bromide, lithium fluoride, lithium iodide, lithium hydroxide, lithium carbonate, heavy carbonate, It is one or more selected from the group consisting of lithium carbonate, lithium phosphate, lithium dihydrogen phosphate, dilithium hydrogen phosphate, lithium metaphosphate, lithium acetate and lithium sulfate.

Embodiment 4
According to the method for producing lithium difluorophosphate using the difluorophosphate of Embodiment 1, the molar ratio of the difluorophosphate, lithium salt, and water is 1: 2: 2 to 1: 1: 0.01. It is.

Embodiment 5
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the fluorinating agent is potassium fluoride, sodium fluoride, cesium fluoride, triethylamine trihydrofluoride, pyridine fluoride. One or more selected from the group consisting of hydrogen salts and ammonium fluoride.

Embodiment 6
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the catalyst is selected from the group consisting of a quaternary ammonium salt system, a polyether system, and a quaternary phosphonium salt, or There are multiple species.

Embodiment 7
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the method for producing lithium difluorophosphate is performed under protection of nitrogen gas.

Embodiment 8
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the reaction molar ratio of the dihalophosphate ester compound to the fluorinating agent is 1: (1-3).

Embodiment 9
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the ratio of the mass of the dihalophosphate ester compound to the volume of the nonaqueous solvent is (0.1 to 0.5): ( 1-5).

Embodiment 10
According to the method for producing lithium difluorophosphate using the difluorophosphate of embodiment 1, the molar ratio of the dihalophosphate compound to the catalyst is 1: (0.01-1).

  Hereinafter, the present invention will be described specifically by way of examples. In addition, the following examples are only for further explaining the present invention, and do not limit the protection scope of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the contents of the present invention described above are also included in the protection scope of the present invention.

  All raw materials are commercially available unless otherwise specified.

Example 1
In a dry reaction kettle, under protection of nitrogen gas, 29.9 g (0.1 mol) of C ₆ H ₅ PO ₂ Br ₂ , 1.6 g (0.2 mol) of potassium fluoride, 0.55 g (0 0.005 mol) of tetramethylammonium chloride is added to 300 ml of dry toluene, the temperature of the reaction vessel is slowly raised to 115 ° C. while stirring, and the reaction is allowed to proceed for 15 hours at the same temperature. , Filtered and concentrated to remove toluene, yielding an oil, and distilled under reduced pressure to give 14.3 g of C ₆ H ₅ PO ₂ F ₂ .

In another dry reaction kettle, under the protection of nitrogen gas, add 3.83 g (0.16 mol) lithium hydroxide and 1.8 g (0.1 mol) water at room temperature to 100 ml dry ethylene glycol dimethyl ether, While stirring, 14.3 g of C ₆ H ₅ PO ₂ F ₂ was added dropwise, the temperature of the reaction kettle was controlled to 50 ° C. or lower, and after completion of the addition, the reaction was carried out for 5 hours while maintaining at 45 ° C. The solvent is evaporated at rt and the resulting solid is redissolved with fresh and dry tetrahydrofuran and then recrystallized at -25 to 0 ° C. to produce a crystalline product in solution and then filtered. After removing the mother liquor, the crystalline solid was collected and vacuum dried at 60 ° C. to obtain 6.4 g of LiPO ₂ F ₂ which is a crystalline solid. The purity was 99.3%.

Example 2
In a dried reaction kettle, under nitrogen gas protection, 25.2 g (0.1 mol) C ₂ H ₅ PO ₂ Br ₂ and 12.6 g (0.3 mol) sodium fluoride, 0.32 g ( 0.001 mol) of tetrabutylammonium bromide was added to 300 ml of dry acetonitrile, the temperature of the reaction vessel was raised to 50-60 ° C. while stirring, and the reaction was continued for 20 hours at the same temperature. Then, the temperature was lowered and filtered and distilled to obtain 10.3 g of C ₂ H ₅ PO ₂ F ₂ .

In another dry reaction kettle, under nitrogen gas protection, add 5.09 g (0.12 mol) lithium chloride and 0.9 g (0.05 mol) water to 100 ml dry tetrahydrofuran at room temperature with stirring. 10.3 g of C ₂ H ₅ PO ₂ F ₂ was slowly added dropwise, the temperature of the reaction kettle was controlled to 60 ° C. or lower, and after completion of the addition, the reaction was allowed to proceed for 5 hours while maintaining the temperature at 55 ° C. And the solid obtained is redissolved with fresh and dry tetrahydrofuran and then recrystallized at -25 to 0 ° C. to form a crystalline product in the solution and then filtered to remove the mother liquor. After removal, the crystalline solid was collected and dried in vacuo at 60 ° C. to obtain 6.0 g of LiPO ₂ F ₂ which is a crystalline solid. The purity was 99.0%.

Example 3
In a dry reaction kettle, under the protection of nitrogen gas, 47.5 g (0.2 mol) CH ₃ PO ₂ Br ₂ , 18.52 g (0.5 mol) ammonium fluoride, 0.66 g (0.003 mol) at room temperature. ) Tetraethylene glycol dimethyl ether is added to 300 ml of dry acetonitrile, the temperature of the reaction vessel is slowly raised to 50-60 ° C. while stirring, and the reaction is allowed to proceed for 20 hours at the same temperature. The temperature was lowered, filtered and distilled to obtain 18.3 g of CH ₃ PO ₂ F ₂ .

In another dry reaction vessel, under the protection of nitrogen gas, 8.48 g (0.2 mol) of lithium chloride and 0.9 g (0.05 mol) of water at room temperature were added to 100 ml of dry acetonitrile and stirred. 18.3 g of CH ₃ PO ₂ F ₂ was slowly added dropwise, the temperature of the reaction kettle was controlled to 60 ° C. or lower, and after completion of the addition, the reaction was allowed to proceed for 5 hours while maintaining 55 ° C., and then the solvent was evaporated under reduced pressure The solid obtained is redissolved with fresh and dry acetonitrile and then recrystallized at −25 to 0 ° C. to form a crystalline product in the solution and filtered to remove the mother liquor. The crystalline solid was collected and vacuum-dried at 60 ° C. to obtain 12.5 g of LiPO ₂ F ₂ as a crystalline solid. The purity was 99.1%.

Example 4
In a dry reaction kettle, under nitrogen gas protection, 38.2 g (0.2 mol) CH ₃ (CH ₂ ) ₃ PO ₂ Cl ₂ , 18.52 g (0.5 mol) ammonium fluoride, 0. 66 g (0.003 mol) of tetraethylene glycol dimethyl ether was added to 300 ml of dry acetonitrile, the temperature of the reaction vessel was slowly raised to 50-60 ° C. while stirring, and the reaction was continued for 20 hours at the same temperature. The temperature was lowered to room temperature, filtered and distilled to obtain 24.3 g of CH ₃ (CH ₂ ) ₃ PO ₂ F ₂ .

In another dry reaction vessel, under the protection of nitrogen gas, 8.48 g (0.2 mol) of lithium chloride and 0.9 g (0.05 mol) of water at room temperature were added to 100 ml of dry acetonitrile and stirred. 24.3 g of CH ₃ (CH ₂ ) ₃ PO ₂ F ₂ is slowly added dropwise, the temperature of the reaction kettle is controlled to 60 ° C. or lower, and after completion of the addition, the reaction is allowed to proceed for 5 hours while maintaining 55 ° C. The solvent was evaporated under reduced pressure and the resulting solid was redissolved with fresh and dry acetonitrile, then recrystallized at -25 to 0 ° C. to produce a crystalline product in the solution and filtered. The mother liquor was removed, and the crystalline solid was collected and dried in vacuo at 60 ° C. to obtain 12.0 g of LiPO ₂ F ₂ which is a crystalline solid. The purity was 99.2%.

  The above examples are illustrative and are merely illustrative of the features of the present disclosure. The appended claims are intended to protect all possible scope and examples herein are intended to describe embodiments selected from combinations of all possible examples. Not too much. Accordingly, the scope of the appended claims is not limited to the selection of example features that illustrate the invention. Technological advances also form possible equivalents or sub-substitutions that are not currently considered due to inaccuracies in linguistic expressions, and these changes are claimed in the claims where possible. Should be interpreted as included.

The present invention provides a method for producing lithium difluorophosphate using a difluorophosphate ester. In this method, a dihalophosphate compound is obtained by reacting a dihalophosphate compound with a fluorinating agent in a non-aqueous solvent under the action of a catalyst to obtain a difluorophosphate compound, and the difluorophosphate obtained in step (1). Reacting the acid ester compound, lithium salt and water in a non-aqueous solvent to obtain lithium difluorophosphate (2).

The dihalophosphate compound is represented by the following formula (1).

In the formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br and I (however, both X and Y are not F at the same time) . And R is a hydrocarbon group.

As one embodiment of the present invention, the nonaqueous solvent in the above step (2) is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene. , Acetonitrile, methyl ether, ethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole, and tetrahydrofuran.

The present invention provides a method for producing lithium difluorophosphate using a difluorophosphate ester. In this method, a dihalophosphate compound is obtained by reacting a dihalophosphate compound with a fluorinating agent in a non-aqueous solvent under the action of a catalyst to obtain a difluorophosphate compound, and the difluorophosphate obtained in step (1). Reacting the acid ester compound, lithium salt and water in a non-aqueous solvent to obtain lithium difluorophosphate (2).

The dihalophosphate compound is represented by the following formula (1).

In the formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br and I (however, both X and Y are not F at the same time) . And R is a hydrocarbon group.
The specific reaction formula is
RPO ₂ XY + MF → RPO ₂ F ₂ + MX + MY (reaction (2))

In one embodiment of the present invention, the nonaqueous solvent in the above step ( 1 ) is n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene. It is at least one selected from the group consisting of glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole and tetrahydrofuran.

As one embodiment of the present invention, the nonaqueous solvent in the above step (2) is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene. And at least one selected from the group consisting of acetonitrile, methyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole and tetrahydrofuran.

Embodiment 1
The present invention provides a method for producing lithium difluorophosphate using a difluorophosphate ester. In this method, a dihalophosphate compound is obtained by reacting a dihalophosphate compound with a fluorinating agent in a non-aqueous solvent under the action of a catalyst to obtain a difluorophosphate compound, and the difluorophosphate obtained in step (1). Reacting the acid ester compound, lithium salt and water in a non-aqueous solvent to obtain lithium difluorophosphate (2).

The dihalophosphate compound is represented by the following formula (1).

In the formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br and I (however, both X and Y are not F at the same time) . And R is a hydrocarbon group.

Embodiment 2
According to the method for producing lithium difluorophosphate using the difluorophosphate ester of Embodiment 1, the nonaqueous solvent in step (2) is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane. , Cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether, diethyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole and tetrahydrofuran 1 type or multiple types.

Claims (10)

(1) obtaining a difluorophosphate compound by reacting the dihalophosphate compound with a fluorinating agent under the action of a catalyst;
And (2) a step of reacting the difluorophosphate ester compound obtained in step (1), a lithium salt and water in a non-aqueous solvent to obtain lithium difluorophosphate,
The dihalophosphate compound is represented by the following formula (1):
In formula (1), X and Y are each independently one selected from the group consisting of F, Cl, Br, and I, and R is a hydrocarbon group, A method for producing lithium difluorophosphate using an ester.   The non-aqueous solvent is cyclic carbonate, chain carbonate, cyclic ester, chain ester, n-hexane, cyclohexane, n-heptane, isoheptane, benzene, toluene, xylene, acetonitrile, methyl ether, diethyl ether, ethylene glycol dimethyl ether, The difluoro using the difluorophosphate ester according to claim 1, wherein the difluorophosphate ester is one or more selected from the group consisting of ethylene glycol diethyl ether, propylene glycol dimethyl ether, diethylene glycol dimethyl ether, anisole, phenetole and tetrahydrofuran. A method for producing lithium phosphate.   The lithium salt is lithium chloride, lithium bromide, lithium fluoride, lithium iodide, lithium hydroxide, lithium carbonate, lithium bicarbonate, lithium phosphate, lithium dihydrogen phosphate, dilithium hydrogen phosphate, lithium metaphosphate The method for producing lithium difluorophosphate using a difluorophosphate ester according to claim 1, wherein the method is one or more selected from the group consisting of lithium acetate and lithium sulfate.   2. The difluorophosphorus using the difluorophosphate according to claim 1, wherein the molar ratio of the difluorophosphate, lithium salt and water is 1: 2: 2 to 1: 1: 0.01. Method for producing lithium acid.   The fluorinating agent is one or more selected from the group consisting of potassium fluoride, sodium fluoride, cesium fluoride, triethylamine trihydrofluoride, pyridine hydrofluoride, and ammonium fluoride. A method for producing lithium difluorophosphate using the difluorophosphate according to claim 1.   The difluorophosphate ester according to claim 1, wherein the catalyst is one or more selected from the group consisting of a quaternary ammonium salt, a polyether, and a quaternary phosphonium salt. A method for producing lithium difluorophosphate.   The method for producing lithium difluorophosphate using a difluorophosphate ester according to claim 1, wherein the method for producing lithium difluorophosphate is performed under protection of nitrogen gas.   The method for producing lithium difluorophosphate using a difluorophosphate according to claim 1, wherein the reaction molar ratio of the dihalophosphate compound to the fluorinating agent is 1: (1 to 3).   The ratio of the mass of the said dihalophosphate compound and the volume of a nonaqueous solvent is (0.1-0.5) :( 1-5), The difluorophosphate ester of Claim 1 characterized by the above-mentioned. The manufacturing method of the used lithium difluorophosphate.   The method for producing lithium difluorophosphate using a difluorophosphate according to claim 1, wherein the molar ratio of the dihalophosphate compound to the catalyst is 1: (0.01 to 1).