KR102660204B1 - Method for manufacturing cesium fluoro oxalato phosphate with high purity - Google Patents

Abstract

The present invention provides cesium difluorobis(oxalato)phosphate (CsDFBOP) or cesium tetrafluoro(oxalato)phosphate (CsTFOP), which are useful as additives in electrolytes for lithium secondary batteries. ) relates to a method of producing high purity solid.

Description

Method for manufacturing cesium fluoro oxalato phosphate with high purity}

The present invention provides cesium fluoro oxalato phosphate, that is, cesium difluorobis(oxalato) phosphate (CsDFBOP) or cesium tetrafluoro (oxalato) phosphate, which can be used in electrolyte additives for secondary batteries. This relates to a method of producing cesium tetrafluoro(oxalato)phosphate (CsTFOP) as a high purity solid.

A method for manufacturing lithium difluorobis(oxalato)phosphate (LiDFBOP), which is used as a non-aqueous electrolyte additive to improve the performance of lithium secondary batteries, lithium ion capacitors, etc., is disclosed in Korean Patent Publication No. 2011-0086102.

Specifically, silicon tetrachloride (SiCl ₄ ) was added dropwise to a mixed solution of lithium hexafluorophosphate (LiPF ₆ ) and oxalic acid, and then reacted at elevated temperature to produce lithium difluoride having a mass percent ratio of about 66:1 to 2.3:1. A solution of bis(oxalato)phosphate/lithium tetrafluoro(oxalato)phosphate (LiDFBOP/LiTFOP) can be obtained, and this method produces lithium difluorobis(oxalato)phosphate (LiDFBOP), which is difficult to purify by crystallization. It is described that a method for producing a lithium difluorobis(oxalato)phosphate (LiDFBOP) solution containing low chlorine compounds or free acids is provided.

However, in the above manufacturing method, fluorotrimethylsilane (TMSF) and volatile substances contained as by-products can be removed by reducing pressure, but lithium difluorobis(oxalato)phosphate/lithium tetrafluoride is used according to the adjustment of the equivalent weight of the reactant during manufacturing. It is produced as a mixture of lo(oxalato)phosphate (LiDFBOP/LiTFOP). In addition, chlorine compounds and free acids still exist in the obtained lithium difluorobis(oxalato)phosphate (LiDFBOP) solution, which may adversely affect battery performance when used as an additive in a non-aqueous electrolyte battery.

In addition, Japanese Patent Publication No. 2003-137890 discloses oxalic acid and lithium tetrafluoroborate (LiBF ₄ ) or lithium in the presence of a catalyst of silicon tetrachloride or aluminum trichloride and a non-aqueous solvent such as dimethyl carbonate, diethyl ether, or gamma-butyrolactone. By reacting fluorine-containing compounds such as hexafluorophosphate (LiPF ₆ ), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoro(oxalato)phosphate (LiTFOP) and lithium bis(oxalato)borate ( Although the manufacturing method of LiBOB) is described, a purification process to remove the solvent and precipitate crystals is essential.

However, the above production method not only does not mention the extraction and purity of lithium difluorobis(oxalato)phosphate (LiDFBOP), but is also not implemented at all for metals other than lithium. Because excessive amounts of oxalic acid are used, removal of residual oxalic acid is required through an additional process, and corrosion of the reactor may occur due to by-products generated during the removal process.

The lithium difluorobis(oxalato)phosphate (LiDFBOP), lithium difluoro(oxalato)borate (LiDFOB), lithium tetrafluoro(oxalato)phosphate (LiTFOP) and lithium bis(oxalato)borate (LiBOB) ) All are completely dissolved in the solvent and must undergo a purification process. In particular, in the case of lithium difluorobis(oxalato)phosphate (LiDFBOP), it has a very strong affinity with solvents, so it is difficult to purify by crystallization, and there are no chlorine compounds or free acids that greatly adversely affect the performance of non-aqueous electrolyte batteries. It is impossible to obtain lithium difluorobis(oxalato)phosphate (LiDFBOP) in that state, i.e. in high purity.

Therefore, a method for producing fluoro-oxalate phosphate alkali metal salt with high purity is required so that chlorine compounds or free acids that significantly adversely affect the performance of non-aqueous electrolyte batteries are not present.

Korean Patent Publication 10-2011-0086102 Japanese Patent Publication No. 2003-137890

The present inventors reacted cesium hexafluorophosphate and oxalic acid in a non-aqueous solvent according to the dropwise addition of silicon tetrachloride to produce cesium fluoro oxalatophosphate, which can be used as an electrolyte additive, as a precipitate without dissolving in the non-aqueous solvent, and thus ether. The present invention was completed by discovering that unreacted oxalic acid was completely removed by simple filtration after adding the solvent to obtain solid cesium fluorooxalatophosphate with a high purity of 99.9% or more.

The purpose of the present invention relates to a method for efficiently producing cesium fluorooxalatophosphate, which is useful as an additive for electrolyte solutions for lithium secondary batteries, in a high-purity solid phase by utilizing the difference in solubility between reactants and products.

The present invention provides a method for efficiently producing high-purity solid cesium fluorooxalatophosphate, which is useful as an additive for electrolyte solutions for lithium secondary batteries, and specifically, mixing cesium hexafluorophosphate of the following formula (2), oxalic acid, and a non-aqueous solvent. and adding silicon tetrachloride dropwise and reacting to prepare cesium fluorooxalatophosphate of the following formula (1); And a step of adding and filtering an ether-based organic solvent.

[Formula 1]

[Formula 2]

(In Formula 1, m is an integer of 1 or 2.)

In one embodiment of the present invention, the non-aqueous solvent may be one or more non-aqueous solvents selected from the group consisting of cyclic carbonates, chain carbonates, chain nitriles, cyclic esters, chain esters, and chain halogenated solvents.

In one embodiment of the present invention, the non-aqueous solvent is dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethyl methyl carbonate, methyl propyl carbonate, methyl isopropyl carbonate, ethyl propyl carbonate, ethylene carbonate, propylene carbonate, butyl It may be one or two or more selected from the group consisting of lene carbonate, acetonitrile, propionitrile, butyrolactone, valerolactone, ethyl acetate, ethyl propionate, dichloromethane, and 1,2-dichloroethane.

In one embodiment of the present invention, the silicon tetrachloride may be used in the range of 0.5 to 1.5 mole per 1 mole of cesium hexafluorophosphate of Chemical Formula 2.

In one embodiment of the present invention, the oxalic acid may be used in the range of 1.0 to 5.0 mole per 1 mole of cesium hexafluorophosphate of Chemical Formula 2.

In one embodiment of the present invention, the reaction may be performed in the range of 0 to 30 °C.

In one embodiment of the present invention, the ether-based solvent may be linear ether, cyclic ether, or a combination thereof.

In one embodiment of the present invention, the linear ether is dimethyl ether, diethyl ether, Dipropyl ether, dibutyl ether, diisobutyl ether, ethyl methyl ether, ethyl propyl ether, ethyl t-butyl ether, dimethoxymethane, trimethoxymethane, dimethoxyethane, diethoxyethane, dimethoxypropane, diethylene Glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, diethylene glycol ethylmethyl ether, One or two or more selected from the group consisting of diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether, diethylene glycol t-butyl ethyl ether, and ethylene glycol ethyl methyl ether, and the cyclic ether is dioxolane, methyl dioc Solan, dimethyldioxolane, vinyldioxolane, methoxydioxolane, ethylmethyldioxolane, oxane, dioxane, trioxane, tetrahydrofuran, methyltetrahydrofuran, dimethyltetrahydrofuran, dimethoxytetrahydrofuran, It may be one or two or more selected from the group consisting of ethoxytetrahydrofuran, dihydropyran, tetrahydropyran, furan, and methylfuran.

In one embodiment of the present invention, the high purity cesium fluoro oxalatophosphate solid may have a purity of 99% or more.

According to the manufacturing method of the present invention, cesium fluoro-oxalatophosphate, that is, cesium difluorobis(oxalato)phosphate (CsDFBOP) or cesium tetrafluoromono(oxalate), can be used as an effective additive to improve the performance of non-aqueous electrolyte batteries. Lato) phosphate (CsTFOP) is prepared in a solid form by reacting cesium hexafluorophosphate and oxalic acid in a non-aqueous solvent according to the dropwise addition of silicon tetrachloride, and then an ether-based solvent is added and simple filtration is performed to completely remove unreacted oxalic acid. Cesium difluorobis(oxalato)phosphate (CsDFBOP) or cesium tetrafluoro(oxalato)phosphate (CsTFOP) can be efficiently produced in solid phase with a high purity of 99% or more.

That is, according to the production method of the present invention, cesium difluorobis(oxalato)phosphate (CsDFBOP) or cesium tetrafluoro(oxalato)phosphate, which are useful as additives in electrolyte solutions for lithium secondary batteries, utilizes the difference in solubility between reactants and products. (CsTFOP) can be produced in a high-purity solid phase.

In particular, in the case of cesium, its affinity for solvents is quite poor compared to other metals of the same group, so as the reaction progresses, it can immediately precipitate as a complete solid in a non-aqueous solvent. Therefore, compared to other alkali metals, oxalatophosphate salt containing cesium can be obtained as a solid with a high purity of 99% or more.

In addition, according to the production method of the present invention, cesium difluorobis(oxalato)phosphate (CsDFBOP) or cesium tetrafluoro(oxalato)phosphate (CsTFOP) is formed as a solid during the reaction, so it can be used as an additive to the non-aqueous electrolyte solution. It can be manufactured economically and industrially without contamination from chlorine compounds and free acids, which greatly adversely affect battery performance during use.

In addition, according to the manufacturing method of the present invention, cesium difluorobis(oxalato)phosphate (CsDFBOP) or cesium tetrafluoro(oxalato)phosphate (CsTFOP) has a moisture content, which is one of the factors causing problems in battery performance. This low value makes it very suitable as an additive for non-aqueous electrolytes.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein.

Also, unless otherwise defined, all technical and scientific terms have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention pertains. The terminology used in the description herein is merely to effectively describe specific embodiments and is not intended to limit the invention.

Additionally, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to also include the plural forms, unless the context clearly dictates otherwise.

The present invention provides a method for efficiently producing high-purity solid cesium fluorooxalatophosphate, which is useful as an additive for electrolyte solutions for lithium secondary batteries, and specifically, mixing cesium hexafluorophosphate of the following formula (2), oxalic acid, and a non-aqueous solvent. and adding silicon tetrachloride dropwise and reacting to prepare cesium fluorooxalatophosphate of the following formula (1); And a step of filtering by adding an ether-based solvent.

[Formula 1]

[Formula 2]

(In Formula 1, m is an integer of 1 or 2.)

In Formula 1, cesium difluorobis(oxalato)phosphate (CsDFBOP) with m of 2 or cesium tetrafluoro(oxalato)phosphate (CsTFOP) with m of 1 is lithium difluorobis(oxalato)phosphate, respectively. (LiDFBOP) or lithium tetrafluoro(oxalato)phosphate (LiTFOP), but has the same structure as difluorobis(oxalato)phosphate or tetrafluoro(oxalate) containing cesium, a Group 1 alkali metal, instead of lithium. ) Phosphate, it can be effective as an electrolyte additive to improve the performance of lithium secondary batteries, lithium ion capacitors, etc., in the same way as LiDFBOP or LiTFOP.

However, conventionally, only the production method of lithium difluorobis(oxalato)phosphate (LiDFBOP) and lithium tetrafluoro(oxalato)phosphate (LiTFOP) is known, and oxalate phosphate containing cesium among alkali metals. There is nothing known about the manufacturing method.

The present inventors completed the present invention by discovering that, although it is a metal element of the same group, the solubility of difluorobis(oxalato)phosphate metal salt is completely different in non-aqueous solvents depending on the type of metal contained therein. LiDFOP, which has a very strong affinity for solvents and exists in a completely dissolved state in organic solvents, is very difficult to purify into a solid, so it is a high-purity solution that does not contain chlorine compounds or free acids that greatly adversely affect the performance of non-aqueous electrolyte batteries. There is a problem in that it is impossible to obtain lithium fluorobis(oxalato)phosphate.

However, cesium fluorooxalatophosphate of Chemical Formula 1, prepared by reacting cesium hexafluorophosphate of Chemical Formula 2 and oxalic acid in a non-aqueous solvent under the dropwise addition of silicon tetrachloride according to the production method of the present invention, has unique properties of cesium metal. Therefore, unlike other alkali metals of the same group, it has very poor affinity with solvents and precipitates as a solid in non-aqueous solvents, so it can be obtained as a high-purity solid.

The non-aqueous solvent according to an embodiment of the present invention is an inert non-aqueous solvent that does not react with reactive components, and is one or two selected from the group consisting of cyclic carbonates, chain carbonates, chain nitriles, cyclic esters, chain esters, and chain halogenated solvents. Any of the above non-aqueous solvents may be used. For example, cyclic carbonates such as ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), vinylene carbonate (VC), dimethyl carbonate (DMC), diethyl carbonate (DEC), and dipropyl carbonate. Chain carbonates such as (DPC), methyl ethyl carbonate (MEC), methyl propyl carbonate (MPC), methyl isopropyl carbonate, and ethyl propyl carbonate (EPC), chain nitriles such as acetonitrile and propionitrile, butyrolactone, and valeric acid. Cyclic esters such as rolactone, chain esters such as ethyl acetate and ethyl propionate, and chain halogenated solvents such as dichloromethane and 1,2-dichloroethane may be used, but are not limited thereto. These non-aqueous solvents are preferably dehydrated, and the moisture concentration in the non-aqueous solvent used in the present invention may preferably be 100 ppm by weight or less.

The concentration of cesium hexafluorophosphate of Formula 2 in the non-aqueous solvent according to an embodiment of the present invention is not particularly limited, but is preferably 1 to 40% by weight, more preferably 3 to 30% by weight, and even more. Preferably it may be in the range of 3 to 10% by weight. The reaction can be carried out smoothly within the above concentration range, but if it exceeds 40% by weight, the viscosity of the solution increases, making it difficult to carry out the reaction smoothly, which is not preferable.

Oxalic acid according to an embodiment of the present invention can be obtained by drying commercially available dihydrate. The drying method is not particularly limited and methods such as heating and vacuum drying can be used. The moisture in the dried oxalic acid is 300. It is preferable that it is less than mass ppm.

Oxalic acid according to an embodiment of the present invention may be preferably used in an amount of 1.0 to 5.0 mole, and more preferably in an amount of 1.1 to 3.5 mole in terms of reaction efficiency, per 1 mole of cesium hexafluorophosphate of Formula 2. If the amount of oxalic acid used exceeds 5.0 mol, too much unreacted oxalic acid remains, which lowers the purity of the desired cesium fluorooxalatophosphate, which may affect the performance of the electrolyte solution.

More preferably, when oxalic acid is used in an amount of 1.0 to 1.5 mol per 1 mole of cesium hexafluorophosphate of Formula 2, cesium tetrafluoro(oxalato)phosphate (CsTFOP, corresponding to the case where m in Formula 1 is 1) is high. It can be manufactured with high yield and high purity.

More preferably, when oxalic acid is used in an amount of 2.5 to 3.5 mol per mole of the alkali metal salt of hexafluorophosphate of Formula 2, cesium difluorobis(oxalato)phosphate (CsDFBOP, corresponding to the case where m is 2 in Formula 1) Can be manufactured with high yield and high purity.

Silicon tetrachloride according to an embodiment of the present invention is preferably used in an amount of 0.5 to 1.5 mol, more preferably 0.5 to 1.2 mol, based on 1 mol of cesium hexafluorophosphate of Chemical Formula 2. If the amount of silicon tetrachloride used exceeds 1.5 mol, a large amount of non-volatile chlorine compounds may be generated as by-products.

In one embodiment of the present invention, when 2.5 to 3.5 moles of oxalic acid and 1.0 to 1.5 moles of silicon tetrachloride are used per 1 mole of cesium hexafluorophosphate of Formula 2, cesium difluorobis where m is 2 in Formula 1 (Oxalate)phosphate (CsDFBOP) can be produced efficiently.

In one embodiment of the present invention, when 1.0 to 1.5 moles of oxalic acid and 0.5 to 0.8 moles of silicon tetrachloride are used per 1 mole of cesium hexafluorophosphate of Chemical Formula 2, cesium tetrafluoroacetic acid (m is 1) in Chemical Formula 1 Oxalato)phosphate (CsTFOP) can be produced efficiently.

The reaction between cesium hexafluorophosphate of Chemical Formula 2 and oxalic acid according to an embodiment of the present invention may be carried out in an atmosphere that does not contain moisture, and it is preferable to carry out the reaction in an inert gas atmosphere such as nitrogen or argon. .

The reaction according to an embodiment of the present invention is carried out at 0 to 30°C. Specifically, the mixing of cesium hexafluorophosphate of Chemical Formula 2, oxalic acid and non-aqueous solvent is carried out at 15 to 30°C, and the admixture of silicon tetrachloride is carried out at 15 to 30°C. Grinding is carried out at 0 to 10°C. When silicon tetrachloride is added dropwise, high heat is generated due to a violent reaction. In this case, in order to prevent decomposition of PF ₆ ^- of the cesium hexafluorophosphate of formula 2, which is vulnerable to heat, it is preferable that the dropwise addition of silicon tetrachloride is carried out at 0 to 10°C. do.

The method for producing cesium fluoro oxalate phosphate of the present invention allows the reaction to proceed under mild conditions and can easily obtain a high yield and high purity solid product, enabling mass production.

In the production method according to an embodiment of the present invention, as the reaction between cesium hexafluorophosphate of Formula 2 and oxalic acid proceeds according to the dropwise addition of silicon tetrachloride, cesium fluorooxalatophosphate of Formula 1 reacts in a solid phase. It precipitates in the mixture, and in order to separate and purify it, it goes through a process of filtration by adding an ether-based solvent. After adding the ether-based solvent, the cesium fluorooxalatophosphate solid of Formula 1 is completely separated with high purity from the reaction mixture containing dissolved impurities such as by-products, chlorine compounds, free acid, unreacted oxalic acid, etc., through simple filtration. can do.

In the production method according to an embodiment of the present invention, the cesium fluorooxalatophosphate of Formula 1, obtained by completely removing unreacted oxalic acid and impurities through simple filtration after adding an ether-based solvent, is added as an electrolyte additive. It has a high purity of over 99% that allows it to be used immediately without going through impurity removal and purification processes.

In one embodiment of the present invention, the step of additionally washing the cesium fluorooxalatophosphate of Chemical Formula 1 obtained after the filtration with an ether-based solvent may be included once to several times.

Hereinafter, the present invention will be described in more detail through specific examples and comparative examples. The following examples are intended to illustrate the present invention, and the present invention is not limited by the following examples.

[Example 1] Preparation of high purity cesium difluorobis(oxalato)phosphate (CsDFBOP) solid

Cesium hexafluorophosphate (CsPF ₆ ) (22.14 g, 0.08 mol) and oxalic acid (22.14 g, 0.24 mol) were added to a 2L flask at room temperature, and after forming stable reaction conditions with nitrogen, dimethyl carbonate (420 mL) was added. Added and stirred for 2 hours. When stirring was completed, the reaction temperature was lowered to 0°C using ice water, and silicon tetrachloride (SiCl ₄ ) (10.15 mL, 0.08 mol) was slowly added dropwise over 30 minutes. When the dropwise addition of silicon tetrachloride was completed, the reaction temperature was warmed to room temperature and stirred for 12 hours. After completion of stirring, diethyl ether (Et ₂ O) (300 mL) was added to dilute the reaction mixture, stirred for additional 1 hour, and then filtered to separate the solid. The separated solid was further washed with diethyl ether (Et ₂ O) (300 mL) and then dried under reduced pressure in vacuum to obtain cesium difluorobis(oxalato)phosphate (CsDFBOP) as a white solid (30.58 g, 0.08 mol, 100% yield, 99.5% ( ^19F NMR purity)). The final product was analyzed using nuclear magnetic resonance equipment and Karl-Fisher moisture analysis equipment.

¹⁹ F NMR (500 MHz, DMSO-d ₆ ): δ -60 (d, F) ppm; Moisture content by oven Karl-Fisher instrument 315 ppm.

[Example 2] Preparation of high purity cesium tetrafluoro(oxalato)phosphate (CsTFOP) solid

Cesium hexafluorophosphate (CsPF ₆ ) (4.65 g, 0.017 mol) and oxalic acid (1.75 g, 0.019 mol) were added to a 250 mL flask at room temperature, and after forming stable reaction conditions with nitrogen, dimethyl carbonate (80 mL) was added. was added and stirred for 2 hours. When stirring was completed, the reaction temperature was lowered to 0°C using ice water, and silicon tetrachloride (SiCl ₄ ) (0.98 mL, 0.0085 mol) was slowly added dropwise over 5 minutes. When the dropwise addition of silicon tetrachloride was completed, the reaction temperature was warmed to room temperature and stirred for 12 hours. After completion of stirring, diethyl ether (Et ₂ O) (60 mL) was added to dilute the reaction mixture, stirred for additional 1 hour, and then filtered to separate the solid. The separated solid was further washed with diethyl ether (Et ₂ O) (30 mL) and then dried under reduced pressure in vacuum to obtain cesium tetrafluoro(oxalato)phosphate (CsTFOP) as a white solid (4.92 g, 0.015 mL). mol, approximately 89% yield, 99.5% ( ^19F NMR purity)). The final product was analyzed using nuclear magnetic resonance equipment.

¹⁹ F NMR (500 MHz, DMSO-d ₆ ): δ -65.5 (t, F), -67.5 (t, F), -78.5 (t, F), -74.0 (t, F) ppm.

[Comparative Example 1] Preparation of cesium difluorobis(oxalato)phosphate (CsDFBOP) solid

Cesium hexafluorophosphate (CsPF ₆ ) (0.23 g, 0.83 mmol) and oxalic acid (0.16 g, 1.74 mmol) were added to a 50 mL flask at room temperature, and after forming stable reaction conditions with nitrogen, dimethyl carbonate (4 mL) was added. was added and stirred for 2 hours. When stirring was completed, the reaction temperature was lowered to 0°C using ice water, and silicon tetrachloride (SiCl ₄ ) (0.15 mL, 0.83 mmol) was slowly added dropwise. When the dropwise addition of silicon tetrachloride was completed, the reaction temperature was warmed to room temperature and stirred for 12 hours. After stirring was completed, the pH (acidity) was measured using pH paper, and then the pressure was reduced under vacuum to remove volatile substances, thereby obtaining the product in solid form.

The pH (acidity) of the final reaction solution was measured with pH paper and was found to be pH = 2. As a result of measuring the weight of the product obtained by removing volatile substances, the yield was calculated to be 130% compared to the desired final product, CsDFBOP. That is, it could be seen from the measured pH and yield that oxalic acid remained in the obtained product. In addition, as a result of NMR analysis of the obtained product, it was confirmed that cesium tetrafluoro(oxalato)phosphate (CsTFOP) was present in addition to the desired final product CsDFBOP. As a result of ¹⁹ F NMR analysis, CsDFBOP:CsTFOP = 4:1 molar ratio was present, and CsDFBOP was confirmed to have a purity level of 80% among the Cs salt ratio. Additionally, substances that could not be identified by ¹ H NMR and ¹⁹ F NMR were mixed.

[Comparative Example 2] Preparation of lithium difluorobis(oxalato)phosphate (LiDFBOP) solid

Add lithium hexafluorophosphate (LiPF ₆ ) (0.44 g, 0.029 mmol) and oxalic acid (0.53 g, 0.058 mol) to a 50 mL flask at room temperature, create stable reaction conditions with nitrogen, and then add dimethyl carbonate (420 mL). was added and stirred for 2 hours. When stirring was completed, the reaction temperature was lowered to 0°C using ice water, and silicon tetrachloride (SiCl ₄ ) (0.33 mL, 0.029 mmol) was slowly added dropwise over 5 minutes. When the dropwise addition of silicon tetrachloride was completed, the reaction temperature was warmed to room temperature and stirred for 12 hours. After stirring was completed, the pH (acidity) was measured using pH paper, and volatile substances were removed by vacuum decompression to obtain a product containing a mixture of white solid and viscous transparent material.

The pH (acidity) of the final reaction solution was measured with pH paper and was found to be pH = 2. As a result of measuring the weight of the product obtained by removing volatile substances, the yield was calculated to be approximately 113% compared to the desired final product LiDFBOP. . That is, it could be seen from the measured pH and yield that oxalic acid remained in the obtained product. In addition, as a result of NMR analysis of the obtained product, it was confirmed that lithium tetrafluoro(oxalato)phosphate (LiTFOP) was present in addition to the desired final product LiDFBOP. As a result of ¹⁹ F NMR analysis, LiDFBOP: LiTFOP = 3: 2 molar ratio was present, and LiDFBOP was confirmed to have a purity level of 60% among the Li salt material ratio. Additionally, substances that could not be identified by ¹ H NMR and ¹⁹ F NMR were mixed.

Claims (9)

Preparing cesium fluorooxalatophosphate of the following formula (1) by mixing cesium hexafluorophosphate of the formula (2), oxalic acid, and a non-aqueous solvent and adding silicon tetrachloride dropwise to react; and
A method for producing cesium fluoro-oxalatophosphate solid, comprising adding an ether-based solvent and filtering it,
The concentration of cesium hexafluorophosphate of Formula 2 in the non-aqueous solvent is 1 to 40% by weight, the oxalic acid is used in the range of 1.0 to 5.0 mole per mole of cesium hexafluorophosphate of Formula 2, and the silicon tetrachloride is used in the range of 0.5 to 1.5 mole based on 1 mole of cesium hexafluorophosphate of Formula 2.
[Formula 1]

[Formula 2]

(In Formula 1, m is an integer of 1 or 2.) According to clause 1,
The non-aqueous solvent is one or two or more non-aqueous solvents selected from the group consisting of cyclic carbonate, chain carbonate, chain nitrile, cyclic ester, chain ester, and chain halogenated solvent. According to clause 2,
The non-aqueous solvent is dimethyl carbonate, diethyl carbonate, dipropyl carbonate, ethylmethyl carbonate, methylpropyl carbonate, methyl isopropyl carbonate, ethylpropyl carbonate, ethylene carbonate, propylene carbonate, butylene carbonate, acetonitrile, propionitrile. , butyrolactone, valerolactone, ethyl acetate, ethyl propionate, dichloromethane, and 1,2-dichloroethane, one or two or more selected from the group consisting of, production method. delete delete According to clause 1,
The production method is that the reaction is carried out in the range of 0 to 30 ° C. According to clause 1,
The production method wherein the ether-based solvent is linear ether, cyclic ether, or a combination thereof. According to clause 7,
The linear ethers include dimethyl ether, diethyl ether, dipropyl ether, dibutyl ether, diisobutyl ether, ethyl methyl ether, ethyl propyl ether, ethyl t-butyl ether, dimethoxymethane, trimethoxymethane, and dimethoxyethane. , diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol One or two or more selected from the group consisting of divinyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether, diethylene glycol t-butyl ethyl ether, and ethylene glycol ethyl methyl ether. And the cyclic ether is dioxolane, methyldioxolane, dimethyldioxolane, vinyldioxolane, methoxydioxolane, ethylmethyldioxolane, oxane, dioxane, trioxane, tetrahydrofuran, methyltetrahydrofuran, A method of producing one or two or more selected from the group consisting of dimethyltetrahydrofuran, dimethoxytetrahydrofuran, ethoxytetrahydrofuran, dihydropyran, tetrahydropyran, furan, and methylfuran. According to any one selected from claims 1 to 3 and claims 6 to 8,
A production method wherein the cesium fluoro oxalatophosphate solid has a purity of 99% or more.