CN114737206B - Preparation method of lithium hexafluorophosphate - Google Patents
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Abstract
The invention belongs to the field of electrochemistry, and particularly relates to a preparation method of lithium hexafluorophosphate. The method comprises the following steps: an electrolytic cell is configured, an anode and a cathode are arranged in the electrolytic cell, potassium ions can be embedded into the cathode, negative ions can be embedded into the anode, a cation exchange membrane is arranged in the electrolytic cell, and the electrolytic cell is divided into an anode area and a cathode area by the cation exchange membrane; respectively injecting electrolyte into a cathode region and an anode region, wherein the electrolyte in the cathode region is a potassium fluoride solution, and the electrolyte in the anode region is a lithium salt solution to form an electrochemical system; and discharging the formed electrochemical system, and simultaneously introducing phosphorus pentafluoride gas into the cathode region until the discharge is completed, thereby completing the preparation of the lithium hexafluorophosphate. The overall scheme is simple and efficient, and the efficient preparation of lithium hexafluorophosphate can be realized by one-step method; the preparation process is safe, and the requirements on equipment and operation are low; the prepared product is convenient to separate and recycle, and has higher yield and purity which can generally reach more than 99.8 percent.
Description
Technical Field
The invention belongs to the field of electrochemistry, and particularly relates to a preparation method of lithium hexafluorophosphate.
Background
Lithium hexafluorophosphate (LiPF) 6 ) The lithium ion battery electrolyte lithium salt is a common and common lithium ion battery electrolyte lithium salt, and experiments prove that the lithium ion battery electrolyte lithium salt has the best comprehensive performance and the best using effect. For this purpose, lithium hexafluorophosphate is produced and preparedIs always a hot spot of research.
Among the current numerous methods of preparation, the conventional methods are three methods, wet method, dry method and solvent method. The wet method comprises the steps of dissolving lithium salt in anhydrous hydrofluoric acid to form LiF-HF solution, introducing phosphorus pentafluoride gas to react to produce lithium hexafluorophosphate crystals, and separating and drying to obtain a product; the dry method is that LiF is treated by anhydrous HF to form porous LiF, and then phosphorus pentafluoride gas is introduced to directly react to obtain a lithium hexafluorophosphate product; the solvent is prepared by reacting lithium salt with alkali metal salt, ammonium salt or organic ammonium salt of hexafluorophosphoric acid in organic solvent and crystallizing. Other methods include a complexing method and an ion exchange method.
However, most of the existing preparation methods have many defects. If the dry preparation requires high temperature and high pressure, the equipment requirement is high, the conversion rate is low, and the conversion is only carried out on the surface, so that the product yield and the purity are low. The wet preparation method brings about great potential safety hazard due to the corrosivity of HF, the reaction needs to be carried out under a low-temperature condition, and the energy consumption is large. The solvent method has low reaction speed, and impurities are easily introduced in the reaction process, so that the product purity is low. Although the complex method has the advantages of low equipment and operation requirements and the like, lithium hexafluorophosphate crystals cannot be obtained even by separation, so that the practical application of the complex method is greatly limited. The ion exchange method has the defects of high cost, large scale production difficulty, low product purity and the like.
Therefore, the development of a brand-new preparation method of lithium hexafluorophosphate has great significance.
Disclosure of Invention
The invention provides a preparation method of lithium hexafluorophosphate, which aims to solve the problems that the existing preparation method of lithium hexafluorophosphate has more or less defects, or has high cost, low cost performance, high difficulty, high danger, poor product yield and quality and the like.
The invention aims to:
1. the preparation method is simple and efficient;
2. the safety of the preparation process is guaranteed;
3. the preparation efficiency is improved;
4. the purity of the obtained product can reach more than 99.8 wt percent.
In order to achieve the purpose, the invention adopts the following technical scheme.
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) The method comprises the following steps of (1) configuring an electrolytic cell, wherein an anode and a cathode are arranged in the electrolytic cell, the cathode is a current collector with a pretreated surface, potassium ions can be embedded into the cathode, the anode is a current collector with a compound which can be embedded into negative ions, a cation exchange membrane is arranged in the electrolytic cell and divides the electrolytic cell into an anode area and a cathode area, the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Respectively injecting electrolyte into a cathode region and an anode region, wherein the electrolyte in the cathode region is a potassium fluoride solution, and the electrolyte in the anode region is a lithium salt solution to form an electrochemical system;
3) And discharging the formed electrochemical system, and simultaneously introducing phosphorus pentafluoride gas into the cathode region until the discharge is completed, thereby completing the preparation of the lithium hexafluorophosphate.
In the technical scheme of the invention, a stable electrochemical system is constructed through the steps 1) and 2). In the constructed electrochemical system, when discharging, the anode loses electrons to capture anions of lithium salt in the anode region, and meanwhile, the cathode of the cathode region obtains electrons to capture potassium ions, so that the potassium ions are embedded into the cathode, and in order to keep the electric neutrality, the lithium ions in the anode region enter the cathode region through a cation exchange membrane, form lithium fluoride with fluoride ions in the cathode region, and then the preparation of lithium hexafluorophosphate can be rapidly realized after phosphorus pentafluoride gas is introduced.
In the process, the ventilation position needs to be controlled between the cathode and the cation exchange membrane, and a porous panel-type pump head is optionally used for forming a bubble net between the cation exchange membrane and the cathode during ventilation so as to improve the reaction efficiency. Meanwhile, the solvent composition of the electrolyte in the cathode region is controlled, the lithium hexafluorophosphate can be prepared and simultaneously crystallized and precipitated directly, the preparation method has great significance for improving the preparation and recovery efficiency, and the purity of the product can be effectively improved.
As a preference, the first and second liquid crystal compositions are,
the pretreatment of the cathode surface in the step 1) is specifically as follows: coating Prussian blue on the surface of a current collector;
the prussian blue is ferricyanide.
The Prussian blue comprises iron ferricyanide, chromium ferricyanide and other conventional ferricyanide salts, and is a key for capturing potassium ions by a cathode by coating the Prussian blue on the surface of a current collector. And Prussian blue compared to other ingredients, including K x VPO 4 F (x～0) And the components are more unique in ion capture when being used in the technical scheme of the invention, so that potassium ions have the capability of being preferentially inserted to form stable compounds, and potassium has a remarkably higher insertion advantage, thereby improving the product yield and ensuring the product purity.
As a preference, the first and second liquid crystal compositions are,
the compound capable of embedding negative ions in the step 1) comprises polyaniline and/or polypyrrole and/or polythiophene and/or polyparaphenylene and/or polytriphenylamine and/or graphene oxide.
There is no particular choice of compound materials that can intercalate anions, and the anode materials selected are common and readily available semiconductor/conductor materials and have the ability to reversibly deintercalate lithium salt anions.
As a preference, the first and second liquid crystal compositions are,
the cation exchange membrane in the step 1) is a sulfonate type cation exchange membrane.
Specifically, the cation exchange membrane used in the invention specifically adopts Nafion TM 211 a cation exchange membrane.
As a preference, the first and second liquid crystal compositions are,
and 2) preparing the potassium fluoride solution by dissolving potassium fluoride in an alcohol-dimethylformamide solution.
Through specific solvent proportion, the solubility of lithium fluoride can be ensured, and the solubility of lithium hexafluorophosphate can be inhibited, so that the formation of lithium fluoride and the transformation and precipitation crystallization of lithium hexafluorophosphate are realized, and the one-step efficient preparation is realized.
Meanwhile, dimethylformamide (DMF) is selected as an important component of the solvent in the invention, because dimethylformamide has almost irreplaceable uniqueness for the technical scheme of the invention. Firstly, the lithium fluoride can be mutually soluble with alcohols, but most importantly, as for potassium fluoride, dimethylformamide has solubility, and the lithium fluoride and ethylene glycol and dimethyl sulfoxide are jointly used as three common organic solvents of potassium fluoride, and meanwhile, lithium fluoride also has good solubility in dimethylformamide. Lithium fluoride is insoluble in alcohol, lithium fluoride can be directly separated out by using ethylene glycol and any other alcohol or monoethylene glycol, the purity of an actual product is low, dimethyl sulfoxide is used as a solubilizer of lithium hexafluorophosphate, and lithium hexafluorophosphate is prepared by using a partial organic solvent method.
As a matter of preference,
step 2) in the potassium fluoride solution: the solvent is prepared from (0.4-0.6): (0.4-0.6) alcohol and dimethylformamide.
The alcohol-to-dimethylformamide ratio needs to be strictly controlled because lithium fluoride is insoluble in alcohol and should be controlled to a low alcohol content to avoid premature and too rapid precipitation of lithium fluoride, but too low an alcohol content will result in dissolution of lithium hexafluorophosphate.
As a preference, the first and second liquid crystal compositions are,
the alcohol is ethylene glycol.
Ethylene glycol is a common industrial alcohol which has the advantages of optimal experimental preparation effect and relatively highest product yield and purity of lithium hexafluorophosphate. Meanwhile, the glycol can improve the solubility of potassium fluoride, compared with other alcohols, the product prepared by using the glycol has obviously higher purity, and compared with common alcohols such as methanol, ethanol, propanol and the like, the average purity is improved by about 0.8-1.6%.
As a preference, the first and second liquid crystal compositions are,
step 3), the discharge is constant current discharge;
the current of the constant current discharge is 30-100A. M 2 。
Controlling the current density enables stable potassium ion intercalation to form lithium fluoride and convert to lithium hexafluorophosphate.
At the same time, however, it should be noted that the aeration flow rate needs to be controlled in accordance with the electrolyte concentration and current density in the cathode region and the anode region to avoid cumulative precipitation of lithium fluoride and loss of lithium ions. It is generally necessary to ensure at least a flow rate of the phosphorus pentafluoride gas up to 0.12 times the amount of the lithium salt substance or the potassium fluoride substance per minute as much as the amount of the phosphorus pentafluoride gas substance introduced. Namely, if the electrolyte in the anode region provides lithium chloride with the concentration of 40 mol and the electrolyte in the cathode region provides potassium fluoride with the dosage of 50 mol, 107.52L phosphorus pentafluoride gas needs to be introduced at least every minute at normal temperature.
The invention has the beneficial effects that:
1) The whole scheme is simple and efficient, and the efficient preparation of lithium hexafluorophosphate can be realized by a one-step method;
2) The preparation process is safe, and the requirements on equipment and operation are low;
3) The prepared product is convenient to separate and recycle, and has higher yield and purity which can generally reach more than 99.8 wt percent.
Drawings
FIG. 1 is a graph showing the relationship between the yield of the product and the content of dimethylformamide in the electrolyte in the cathode region;
FIG. 2 is a graph of product purity versus dimethylformamide content of the electrolyte in the cathode region.
Detailed Description
The invention is described in further detail below with reference to specific embodiments and the attached drawing figures. Those skilled in the art will be able to implement the invention based on these teachings. Moreover, the embodiments of the present invention described in the following description are generally only some embodiments of the present invention, and not all embodiments. Therefore, all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative effort shall fall within the protection scope of the present invention.
Unless otherwise specified, the raw materials used in the examples of the present invention are all commercially available or available to those skilled in the art; unless otherwise specified, the methods used in the examples of the present invention are all those known to those skilled in the art.
Example 1
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is arranged, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector coated with ferric ferricyanide on the surface, the anode is the acetylene black current collector coated with polypyrrole on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM 211 the electrolytic bath is divided into an anode area and a cathode area by a cation exchange membrane, wherein the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Electrolyte is injected into the cathode region and the anode region respectively, potassium fluoride solution of the electrolyte in the cathode region provides KF of 12 mol in total, and a solvent of the potassium fluoride solution is 1:1, the lithium chloride and dimethyl formamide solution of the anode region electrolyte provides 10 mol of lithium fluoride to form an electrochemical system;
3) 60A. M is carried out on the formed electrochemical system 2 And discharging, and simultaneously introducing phosphorus pentafluoride gas into the cathode region, wherein the flow rate of the phosphorus pentafluoride gas is 55L/min, and completing the preparation of the lithium hexafluorophosphate after the discharging is completed.
Recovering 1.5 kg solid in the cathode region, and analyzing and characterizing the solid to obtain the product lithium hexafluorophosphate with the purity of 99.89 percent and the product yield of 98.9 percent.
Example 2
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is arranged, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector coated with ferric ferricyanide on the surface, the anode is the acetylene black current collector coated with polypyrrole on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM 211 the electrolytic bath is divided into an anode area and a cathode area by a cation exchange membrane, wherein the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Electrolyte is injected into the cathode region and the anode region respectively, potassium fluoride solution of the electrolyte in the cathode region provides KF of 12 mol in total, and a solvent of the potassium fluoride solution is 1:1, the lithium chloride and dimethyl formamide solution of the anode region electrolyte provides 10 mol of lithium fluoride to form an electrochemical system;
3) Subjecting the formed electrochemical system to 30A. M 2 And discharging, and simultaneously introducing phosphorus pentafluoride gas into the cathode region, wherein the flow rate of the phosphorus pentafluoride gas is 30L/min, and completing the preparation of the lithium hexafluorophosphate after the discharging is completed.
The yield of the product is recovered and calculated, and the purity of the product is analyzed, the yield of the lithium hexafluorophosphate of the example is 97.6 percent, and the purity of the product is 99.93 percent.
Example 3
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is arranged, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector coated with ferric ferricyanide on the surface, the anode is the acetylene black current collector coated with polypyrrole on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM 211 the electrolytic bath is divided into an anode area and a cathode area by a cation exchange membrane, wherein the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Respectively to cathodic region and anode space injection electrolyte, the potassium fluoride solution of cathodic region electrolyte provides KF totally 12 mol, and the solvent of potassium fluoride solution is volume ratio 1:1, the lithium chloride and dimethyl formamide solution of the anode region electrolyte provides 10 mol of lithium fluoride to form an electrochemical system;
3) Subjecting the formed electrochemical system to 100A. M 2 And discharging, and simultaneously introducing phosphorus pentafluoride gas into the cathode region, wherein the flow rate of the phosphorus pentafluoride gas is 90L/min, and completing the preparation of the lithium hexafluorophosphate after the discharging is completed.
The yield of the product is recovered and calculated, and the purity of the product is analyzed, wherein the yield of the lithium hexafluorophosphate product in the example is 99.1 percent, and the purity of the lithium hexafluorophosphate product is 99.81 percent.
Example 4
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is configured, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector with iron ferricyanide coated on the surface, the anode is the acetylene black current collector with polypyrrole coated on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM The 211 cation exchange membrane divides the electrolytic cell into an anode region and a cathode region, the cathode is positioned in the cathode region, and the anode is positioned in the anode region;
2) Respectively to cathodic region and anode space injection electrolyte, the potassium fluoride solution of cathodic region electrolyte provides KF totally 12 mol, and the solvent of potassium fluoride solution is volume ratio 1:1, the lithium chloride and dimethyl formamide solution of the anode region electrolyte provides 10 mol of lithium fluoride to form an electrochemical system;
3) 60A. M is carried out on the formed electrochemical system 2 And discharging, and simultaneously introducing phosphorus pentafluoride gas into the cathode region, wherein the flow rate of the phosphorus pentafluoride gas is 60L/min, and completing the preparation of the lithium hexafluorophosphate after the discharging is completed.
The yield of the product is recovered and calculated, and the purity of the product is analyzed, wherein the yield of the lithium hexafluorophosphate product in the example is 98.9 percent, and the purity of the product is 99.90 percent.
Example 5
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is arranged, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector coated with ferric ferricyanide on the surface, the anode is the acetylene black current collector coated with polypyrrole on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM 211 the electrolytic bath is divided into an anode area and a cathode area by a cation exchange membrane, wherein the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Electrolyte is injected into the cathode region and the anode region respectively, potassium fluoride solution of the electrolyte in the cathode region provides KF of 12 mol in total, and a solvent of the potassium fluoride solution is 1:1, and lithium fluoride is provided by the lithium chloride dimethylformamide solution of the electrolyte in the anode region, wherein the total amount of the lithium fluoride is 10 mol, so that an electrochemical system is formed;
3) 60A. M is carried out on the formed electrochemical system 2 And discharging, and simultaneously introducing phosphorus pentafluoride gas into the cathode region, wherein the flow rate of the phosphorus pentafluoride gas is 65L/min, and completing the preparation of the lithium hexafluorophosphate after the discharging is completed.
The yield of the product is recovered and calculated, and the purity of the product is analyzed, wherein the yield of the lithium hexafluorophosphate product in the example is 98.7 percent, and the purity of the product is 99.92 percent.
Comparative example 1
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is arranged, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector coated with ferric ferricyanide on the surface, the anode is the acetylene black current collector coated with polypyrrole on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM 211 the electrolytic bath is divided into an anode area and a cathode area by a cation exchange membrane, wherein the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Electrolyte is respectively injected into the cathode region and the anode region, and the potassium hexafluorophosphate solution of the electrolyte in the cathode region provides KPF 6 In total 12 mol of potassium hexafluorophosphate solutionThe solvent is prepared from the following components in a volume ratio of 1:1, the lithium chloride and dimethyl formamide solution of the anode region electrolyte provides 10 mol of lithium fluoride to form an electrochemical system;
3) 60A. M is carried out on the formed electrochemical system 2 And discharging, and simultaneously introducing phosphorus pentafluoride gas into the cathode region, wherein the flow rate of the phosphorus pentafluoride gas is 55L/min, and completing the preparation of the lithium hexafluorophosphate after the discharging is completed.
The product yield was recovered and calculated and analyzed for purity, and the product of this comparative example, lithium hexafluorophosphate, was 99.8% in yield and 96.22% in purity, and the main impurity was potassium hexafluorophosphate.
Comparative example 2
A method for preparing lithium hexafluorophosphate,
the method comprises the following steps:
1) An electrolytic tank is configured, an anode and a cathode are arranged in the electrolytic tank, the cathode is an acetylene black current collector with iron ferricyanide coated on the surface, the anode is the acetylene black current collector with polypyrrole coated on the surface, the areas of the cathode and the anode are equal, and Nafion is arranged in the electrolytic tank TM 211 cation exchange membrane, nafion TM 211 the electrolytic bath is divided into an anode area and a cathode area by a cation exchange membrane, wherein the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Electrolyte is respectively injected into the cathode region and the anode region, and the potassium hexafluorophosphate solution of the electrolyte in the cathode region provides KPF 6 And 12 mol in total, wherein the solvent of the potassium hexafluorophosphate solution is 1:1, the lithium chloride and dimethyl formamide solution of the anode region electrolyte provides 10 mol of lithium fluoride to form an electrochemical system;
3) The formed electrochemical system is processed to 60A. M 2 And discharging to finish the preparation of the lithium hexafluorophosphate.
The product yield was recovered and calculated and analyzed for purity, and the comparative example product, lithium hexafluorophosphate, was 100.7% in yield and 92.09% in purity, and the major impurity was potassium hexafluorophosphate.
By comparing example 1 with comparative examples 1 and 2, it can be found that the electrolyte of the cathode region has a great influence on the purity of the product. The invention particularly adopts potassium fluoride, utilizes the balance of dissolution and precipitation, firstly forms lithium fluoride which can be effectively dissolved, and the lithium fluoride reacts with the blown phosphorus pentafluoride gas to generate lithium hexafluorophosphate, thus quickly separating out and precipitating to obtain the product. If potassium hexafluorophosphate is directly used, precipitation is directly generated in the electrolyte solvent system of the cathode region of the present invention, and potassium hexafluorophosphate is easily driven to co-precipitate in the process, i.e. "catch" potassium hexafluorophosphate to generate impurities, and especially in comparative example 2, the actual impurity content is more without air blowing, which is also the reason.
In contrast, the solvent system of the electrolyte in the cathode region was further adjusted, and the results shown in fig. 1 and 2 were obtained by performing the orthogonal test. And because the content of dimethylformamide in the solvent of the electrolyte in the cathode region is higher than 80 percent VOL, lithium hexafluorophosphate can hardly be directly obtained, and the product is obtained by carrying out recrystallization treatment on the lithium hexafluorophosphate. From the test and detection results in the figure, the product yield is firstly improved and then cliff type is reduced along with the increase of the content of the dimethylformamide, which is mainly caused by the dissolution of the lithium hexafluorophosphate, so that the lithium hexafluorophosphate needs to be recrystallized to obtain a product, and the product obtained by recrystallization contains a large amount of impurities such as potassium hexafluorophosphate and the like, so that the purity of the product obtained by recrystallization is reduced in the cliff type, but the product is rapidly maintained to be stable after the reduction, which also indicates that the adverse effect is caused by the destruction of the dissolution-precipitation balance. In the case of high alcohol concentration, the yield of the product is actually reduced in quality, and the yield of the product is not reduced or even slightly higher than that of the product in example 1 in terms of molar weight, but a large amount of lithium fluoride impurities are mixed in the product.
Therefore, it can be seen from the above test results that, for the technical solution of the present invention, the electrolyte solvent system in the cathode region has a great influence on the implementation effect of the solution, and a fine step test (with 1% VOL as a gradient) shows that the electrolyte glycol-dimethylformamide solvent in the cathode region has a volume content of ethylene glycol of 37-66% VOL, which can achieve a better preparation effect, but the optimal interval should still be limited to a range of 40-60% VOL.
Comparative example 3
On the basis of example 1, the alcohol in the electrolyte solvent of the cathode region was replaced with an organic solvent, and tests were carried out to test the yield and purity of the product, and the results shown in the following table were obtained.
In the table: "+" indicates that the product could not be obtained by direct filtration and was obtained by recrystallization.
As can be seen from the above table, for the technical solution of the present invention, except that ethanol can produce a relatively similar effect, the remaining alcohols or common organic solvents cannot achieve the desired effect of the present invention, so that ethylene glycol has a significant uniqueness to the present invention.
In conclusion, the preparation method can quickly and efficiently realize the preparation of the lithium hexafluorophosphate, has high product yield which can basically reach more than 98 percent, and the purity of the obtained product which can basically reach more than 99.8 percent, has extremely high purity standard, low requirement on equipment, low operation difficulty and huge popularization value.
Claims (5)
1. A preparation method of lithium hexafluorophosphate is characterized in that,
the method comprises the following steps:
1) An electrolytic tank is configured, an anode and a cathode are arranged in the electrolytic tank, the cathode is a current collector with a pretreated surface, potassium ions can be embedded into the cathode, the anode is a current collector with a surface covered with a compound capable of being embedded with negative ions, a cation exchange membrane is arranged in the electrolytic tank and divides the electrolytic tank into an anode area and a cathode area, the cathode is positioned in the cathode area, and the anode is positioned in the anode area;
2) Respectively injecting electrolyte into a cathode region and an anode region, wherein the electrolyte in the cathode region is a potassium fluoride solution, and the electrolyte in the anode region is a lithium salt solution to form an electrochemical system;
3) Discharging the formed electrochemical system, and simultaneously introducing phosphorus pentafluoride gas into the cathode region until the discharge is completed, thereby completing the preparation of the lithium hexafluorophosphate;
wherein:
step 2) the potassium fluoride solution is prepared by dissolving potassium fluoride in an alcohol-dimethylformamide solution;
in the potassium fluoride solution: the solvent is prepared from (0.4-0.6): (0.4-0.6) alcohol and dimethylformamide;
the alcohol is ethylene glycol.
2. The method for preparing lithium hexafluorophosphate of claim 1,
the pretreatment of the cathode surface in the step 1) is specifically as follows: coating Prussian blue on the surface of a current collector;
the Prussian blue is ferricyanide.
3. The method for producing lithium hexafluorophosphate according to claim 1,
the compound capable of embedding negative ions in the step 1) comprises polyaniline and/or polypyrrole and/or polythiophene and/or polyparaphenylene and/or polytriphenylamine and/or graphene oxide.
4. The method for producing lithium hexafluorophosphate according to claim 1,
the cation exchange membrane in the step 1) is a sulfonate type cation exchange membrane.
5. The method for producing lithium hexafluorophosphate according to claim 1,
step 3), the discharge is constant current discharge;
the current of the constant current discharge is 30-100A. M 2 。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202210464825.3A CN114737206B (en) | 2022-04-29 | 2022-04-29 | Preparation method of lithium hexafluorophosphate |
| PCT/CN2022/097821 WO2023206726A1 (en) | 2022-04-29 | 2022-06-09 | Preparation method for lithium hexafluorophosphate |
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| CN202210464825.3A CN114737206B (en) | 2022-04-29 | 2022-04-29 | Preparation method of lithium hexafluorophosphate |
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| US5378445A (en) * | 1993-12-23 | 1995-01-03 | Fmc Corporation | Preparation of lithium hexafluorophosphate solutions |
| JP3483099B2 (en) * | 1997-03-18 | 2004-01-06 | セントラル硝子株式会社 | Method for producing lithium hexafluorophosphate |
| CN1151960C (en) * | 2001-06-11 | 2004-06-02 | 山东省肥城市化肥厂 | Process for preparing lithium hexafluorophosphate in large scale by non-water solvent method |
| JP2011031232A (en) * | 2009-08-04 | 2011-02-17 | Kee:Kk | Method of manufacturing lithium hydroxide |
| CN111304679B (en) * | 2020-03-16 | 2021-01-15 | 武汉大学 | Device and method for preparing high-purity lithium hexafluorophosphate through electrolysis by electrochemical ion extraction method |
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