Silicon difluorophosphate and preparation method thereof

Abstract

This application belongs to the field of battery technology and specifically discloses the preparation of difluorosilyl phosphate and its preparation method. Under conditions of a pressure of 0.01 MPa to 0.6 MPa and a temperature of 5°C to 80°C, an organosilicon alkoxide of formula I and POF3 gas are reacted to obtain a difluorosilyl phosphate of formula II. Formula I and Formula II: wherein R1, R2, and R3 independently comprise any one of a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, or a substituted or unsubstituted phenyl group; M comprises any one of lithium, sodium, and potassium; and POF3 gas is present in an excess of 5% to 30% according to a stoichiometric ratio. In this method, the organosilicon alkoxide of formula I and POF3 gas react readily, with a fast reaction rate, mild reaction conditions, a short reaction time, and a high reaction yield. The resulting fluoride salt is recyclable, and atomic utilization is high.

Description

Technical Field

[0001] The present application belongs to the field of battery technology, and specifically relates to difluorosilyl phosphate and a preparation method thereof. Background Art

[0002] With the rapid development of electronic devices, electric vehicles, smart homes, power tools, and smart transportation, the demand for batteries is also increasing. Currently, most commercial batteries are liquid batteries, that is, batteries contain electrolytes. By adding additives to the electrolyte, the battery's performance can be improved.

[0003] When used as an electrolyte additive in batteries, silicon difluorophosphates (SiFDPs) can reduce initial and post-storage impedance, improving cycling performance. However, the current preparation of SiFDPs with low impurity content, high purity, and high yield requires stringent conditions, making mass production unsuitable. Therefore, the technology for preparing SiFDPs remains to be improved. Summary of the Invention

[0004] The present application aims to solve, at least to some extent, one of the technical problems in the related art. To this end, the present application provides a method for preparing difluorosilyl phosphate with a fast reaction rate, mild reaction conditions, a short reaction time, and a high reaction yield or high atom utilization rate, and the difluorosilyl phosphate prepared by the method.

[0005] The first aspect of the present application provides a method for preparing difluorosilyl phosphate, comprising:

[0006] Under the conditions of a pressure of 0.01 MPa to 0.6 MPa and a temperature of 5° C. to 80° C., reacting the organosilicon alkoxide represented by formula I with POF3 gas to obtain a difluorosilyl phosphate represented by formula II;

[0007] Formula I Formula II

[0008] Wherein, R1, R2, and R3 each independently include any one of C1~C6 alkyl, C2~C6 alkenyl, C2~C6 alkynyl, and substituted or unsubstituted phenyl;

[0009] M includes any one of lithium, sodium, and potassium;

[0010] According to the stoichiometric ratio of the reaction between the organosilicon alkoxide and the POF3 gas, the POF3 gas is in excess of 5% to 30%.

[0011] The preparation method of the first aspect of the present application has at least the following beneficial effects: fast reaction rate, mild reaction conditions, short reaction time and high reaction yield (such as yield ≥80%), the generated fluoride salt can be recycled, and the atomic utilization rate is high.

[0012] In addition, the preparation method according to the above embodiment of the present application may also have the following additional technical features:

[0013] In some embodiments, the reaction of the organosilicon alkoxide and the POF3 gas comprises:

[0014] mixing the organosilicon alkoxide and an organic solvent to obtain a first mixture;

[0015] The POF3 gas is introduced into the first mixture.

[0016] Mixing the organosilicon salt and the organic solvent can, on the one hand, effectively dissolve the organosilicon salt, making the reaction easier to proceed and smoothly obtaining the target product, difluorosilyl phosphate. On the other hand, after the reaction is completed, the organic solvent helps to separate the product and the solvent through conventional means such as distillation and rectification, thereby simplifying the subsequent processing process.

[0017] In some embodiments, the reaction temperature of the organosilicon alkoxide and the POF3 gas can be specifically 20° C. to 40° C. This is conducive to the smooth progress of the reaction and improves the reaction efficiency.

[0018] In some embodiments, the reaction pressure of the organosilicon alkoxide and the POF3 gas can be specifically 0.2 MPa to 0.45 MPa, thereby further improving the reaction rate and reducing impurities in the product.

[0019] In some embodiments, the reaction time of the organosilicon alkoxide and the POF3 gas is 1 hour to 6 hours, specifically 2.5 hours to 4 hours. Thus, the reaction can be completed within the above time range, which helps to reduce the reaction cost.

[0020] In some embodiments, the organic silicon alkoxide and the POF3 gas are reacted under the condition that the water content is ≤50 ppm, thereby effectively reducing the generation of impurities by hydrolysis of difluorosilicone phosphate and obtaining difluorosilicone phosphate with higher purity.

[0021] In some embodiments, the POF3 gas is present in an excess of 20% based on the stoichiometric ratio of the organic silicon alkoxide and the POF3 gas, thereby promoting a more complete reaction, increasing the reaction rate, saving raw materials, and reducing costs.

[0022] In some embodiments, the mass ratio of the organosilicon alkoxide to the organic solvent is 1:2 to 1:8, thereby helping to reduce the moisture in the reaction system without wasting the organic solvent.

[0023] In some embodiments, the organic solvent comprises at least one of dichloromethane, dichloroethane, ethyl acetate, acetonitrile, diethyl ether, ethylene glycol dimethyl ether, and dimethyl carbonate. These organic solvents have excellent solubility, are chemically stable, are unlikely to react with the raw materials, and are easily separated from the product.

[0024] In some embodiments, during the reaction of the organosilicon alkoxide and the POF3 gas, the reaction progress is monitored by NMR F spectroscopy, and the reaction is stopped after the POF3 gas and / or silicon difluorophosphate content remains unchanged. This facilitates a more complete reaction between the organosilicon alkoxide and the POF3 gas without causing waste of raw materials.

[0025] In some embodiments, after the reaction of the organosilicon alkoxide and the POF3 gas is completed, at least one of the following post-processing steps is further included:

[0026] Nitrogen purge to remove POF3 gas;

[0027] filtering to remove the metal fluoride precipitate to obtain a filtrate;

[0028] The filtrate is distilled at 10° C. to 60° C. and -0.09 MPa to 0.098 MPa.

[0029] The above post-treatment steps are beneficial for removing unreacted POF3 gas and product metal fluoride precipitation, thereby improving the purity of difluorosilylphosphate.

[0030] In some embodiments, R1, R2, and R3 each independently include any one of methyl and ethyl.

[0031] In some embodiments, the organosilane alkoxide comprises 、 、 , at least one of triethylsiloxylithium, triethylsiloxysodium, and triethylsiloxypotassium.

[0032] In some embodiments, the difluorosilyl phosphate comprises and At least one of .

[0033] The second aspect of the present application provides a silicon difluorophosphate prepared by the aforementioned method for preparing silicon difluorophosphate. The silicon difluorophosphate has high purity and few impurities, and can be used as an electrolyte additive to effectively reduce side reactions and improve the electrochemical performance of batteries.

[0034] In some embodiments, the purity of the difluorosilyl phosphate is ≥99.0%. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1This is the NMR test P spectrum of the difluorosilyl phosphate prepared in the examples of the present application.

[0036] Figure 2 This is the NMR test F spectrum of the difluorosilyl phosphate prepared in the examples of the present application. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described in detail below, which are intended to explain the present application and should not be construed as limiting the present application.

[0038] This application is based on the following discoveries and understandings of the inventors:

[0039] When difluorosilyl phosphate is used in batteries, it has the effect of reducing initial impedance and impedance after storage, and improving cycle performance. However, the inventors found that the preparation conditions for difluorosilyl phosphate with low impurity content, high purity and high yield are harsh, which is not conducive to mass production. For example, in the related art, trifluorophosphorus oxyfluoride and hexamethyldisiloxane are reacted at room temperature in a molar ratio of 1:1 for 10 days, and then difluorosilyl phosphate and trimethylfluorosilane are separated by distillation to prepare difluorosilyl phosphate. It can be seen that the preparation method in the related art is time-consuming and labor-intensive, which is not conducive to mass production. In this regard, the inventors of this application conducted in-depth exploration of the preparation method of difluorosilyl phosphate and found that organosilicon alkoxide is a nucleophilic reagent. The central metal atom forms a bond with the siloxy group. The metal atom is highly electropositive, which makes the siloxy anion part have a high electron cloud density. As a result, the siloxy anion has a strong electron-donating ability and tends to attack electron-deficient atoms or groups. In contrast, for POF3, the phosphorus atom is connected to the highly electronegative oxygen and fluorine atoms. Oxygen and fluorine strongly attract electrons, which reduces the electron cloud density around the phosphorus atom. The phosphorus atom carries a partial positive charge, becoming an electron-deficient atom, thus making POF3 electrophilic and tending to react with electron-rich nucleophiles. As a result, the inventors developed a method for preparing difluorosilyl phosphate by reacting nucleophiles with electrophiles. The preparation method is simple, mild, has high reaction efficiency, high product yield, and is suitable for mass production.

[0040] In a first aspect, the present application provides a method for preparing difluorosilyl phosphate, comprising:

[0041] Under the conditions of a pressure of 0.01 MPa to 0.6 MPa and a temperature of 5° C. to 80° C., reacting the organosilicon alkoxide represented by formula I with POF3 gas to obtain a difluorosilyl phosphate represented by formula II;

[0042] Formula I Formula II

[0043] Wherein, R1, R2, and R3 each independently include any one of C1~C6 alkyl, C2~C6 alkenyl, C2~C6 alkynyl, and substituted or unsubstituted phenyl;

[0044] M includes any one of lithium, sodium, and potassium;

[0045] According to the stoichiometric ratio of the reaction between the organosilicon alkoxide and the POF3 gas, the POF3 gas is in excess of 5% to 30%.

[0046] The raw materials used in this application are organosilicon alkoxide and POF3, which are nucleophilic and electrophilic reagents respectively. The siloxy anion (nucleophilic part) in the organosilicon alkoxide shown in Formula I will use its own lone pair of electrons to attack the electron-deficient phosphorus atom in POF3, resulting in the breaking of a PF bond in POF3. At the same time, the ionic bond between the oxygen atom and the metal ion in the organosilicon alkoxide is also broken, and the oxygen atom in the siloxy anion uses its own lone pair of electrons to form a bond with the phosphorus atom in POF3 to form a new PO bond, thereby obtaining the product difluorosilyl phosphate, and the fluorine anion (F - ) and free metal ions (M + ) to form a metal fluoride (MF). As a result, the two react rapidly to achieve a more stable electronic structure, allowing for the efficient preparation of difluorosilyl phosphate under mild conditions. This is achieved with a fast reaction rate, short reaction time, and high product yield. The generated fluoride salt is recyclable, resulting in a high atomic utilization rate.

[0047] It should be noted that the term "C1~C6 alkyl" used in this application refers to a saturated straight-chain or branched monovalent hydrocarbon group containing 1-6 carbon atoms. Examples of C1~C6 alkyl include but are not limited to methyl (-CH3), ethyl (-CH2CH3), n-propyl (-CH2CH2CH3), isopropyl (-CH(CH3)2), n-butyl (-CH2CH2CH2CH3), isobutyl (-CH2CH(CH3)2), sec-butyl (-CH(CH3)CH2CH3), tert-butyl (-C(CH3)3), n-pentyl (-CH2CH2CH2CH2CH3), etc.

[0048] The term "C2~C6 alkenyl" refers to a straight or branched monovalent hydrocarbon group containing 2-6 carbon atoms, wherein there is at least one unsaturated site, i.e., one carbon-carbon sp2 double bond. Examples of C2~C6 alkenyl include, but are not limited to, vinyl (-CH=CH2), allyl (-CH2CH=CH2), 1-propenyl (-CH=CH-CH3), and the like.

[0049] The term "C2~C6 alkynyl" refers to a straight or branched monovalent hydrocarbon group containing 2-6 carbon atoms, wherein there is at least one site of unsaturation, i.e., one carbon-carbon sp triple bond. Examples of C2~C6 alkynyl groups include, but are not limited to, ethynyl (-C≡CH), propargyl (-CH2C≡CH), 1-propynyl (-C≡C-CH3), and the like.

[0050] The term "substituted or unsubstituted phenyl" means that the phenyl group is unsubstituted or substituted by one or more substituents, and the substituted phenyl groups include but are not limited to o-methylphenyl, m-methylphenyl, p-methylphenyl, o-ethylphenyl, m-ethylphenyl, p-ethylphenyl, o-dimethylphenyl, etc.

[0051] In some embodiments, R1, R2, and R3 in the organosilicon alkoxide independently comprise any one of a methyl group and an ethyl group. Accordingly, R1, R2, and R3 in the prepared difluorosilyl phosphate independently comprise any one of a methyl group and an ethyl group. Thus, using the difluorosilyl phosphate as a battery electrolyte additive can reduce the initial and post-storage impedance of the battery, effectively improving the battery's cycling performance.

[0052] In some embodiments, the organosilane alkoxide comprises 、 、 , at least one of triethylsiloxylithium, triethylsiloxysodium, and triethylsiloxypotassium.

[0053] In some embodiments, the silicon difluorophosphate comprises and When the above specific compound is used in a battery, the effect of reducing the initial and post-storage impedance of the battery and improving the cycle performance of the battery can be effectively improved.

[0054] In some embodiments, reacting an organosilicon alkoxide with POF3 gas includes mixing the organosilicon alkoxide with an organic solvent to obtain a first mixture. On one hand, the organosilicon alkoxide has high solubility in the organic solvent and is chemically stable, which facilitates reaction with the POF3 gas and substantially reduces side reactions, thereby facilitating a smooth reaction. On the other hand, the organic solvent is easily separated from the product, further reducing impurities in the silicon difluorophosphate and yielding a higher purity silicon difluorophosphate.

[0055] In some embodiments, the organic solvent includes at least one of dichloromethane, dichloroethane, ethyl acetate, acetonitrile, diethyl ether, ethylene glycol dimethyl ether, and dimethyl carbonate.

[0056] In some embodiments, the mass ratio of the organosilicon alkoxide to the organic solvent is 1:2 to 1:8, specifically 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, etc. This helps reduce the moisture in the reaction system without wasting the organic solvent.

[0057] In some embodiments, reacting the organosilicon alkoxide and POF3 gas comprises: introducing POF3 gas into the first mixture for reaction. The reaction equation of the whole process is as follows:

[0058]

[0059] In some embodiments, POF3 gas is introduced into the first mixture for reaction, and the reaction temperature is 5°C to 80°C, specifically, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, etc. In other embodiments, the temperature of the reaction of organosilicon alkoxide and POF3 gas is 20°C to 40°C. Under the above temperature conditions, the reaction efficiency can be further improved, and the conditions are mild, there are few side reactions, the equipment requirements are low, and it is easy to achieve industrial production. As a result, it will not cause problems such as too low temperature affecting the reaction rate and too high temperature requiring high equipment.

[0060] In some embodiments, POF3 gas is introduced into the first mixture for reaction, and the reaction pressure is 0.01MPa~0.6MPa, specifically, 0.01MPa, 0.05MPa, 0.1MPa, 0.15MPa, 0.2MPa, 0.25MPa, 0.3MPa, 0.35MPa, 0.4MPa, 0.45MPa, 0.5MPa, 0.55MPa, 0.6MPa, etc. In other embodiments, the pressure of the reaction of organosilicon alkoxide and POF3 gas can be 0.2MPa~0.45MPa. Under the above pressure conditions, the reaction activity can be significantly improved, the reaction is promoted, and increasing the pressure can increase the concentration of gas molecules, the distance between gas molecules becomes smaller, and the collision frequency becomes faster, thereby accelerating the reaction rate, and difluorosilyl phosphate is efficiently prepared under mild conditions.

[0061] In certain embodiments, POF3 gas is passed into the first mixture to react, and the reaction time is 1h~6h, specifically, 1h, 2h, 3h, 4h, 5h, 6h etc. In other embodiments, the reaction time of organosilicon alkoxide and POF3 gas reaction is 2.5h~4h. Within the above-mentioned reaction time, it can be ensured that the reaction is carried out completely, the reaction efficiency is high, time is not wasted, and cost is relatively low.

[0062] In some embodiments, the organic silicon alkoxide and the POF3 gas are reacted to obtain a water content in the system of ≤50 ppm. Specifically, the water content in the system may be 50 ppm, 45 ppm, 40 ppm, 35 ppm, 30 ppm, 25 ppm, 20 ppm, 15 ppm, 10 ppm, 5 ppm, 1 ppm, etc. This effectively reduces the generation of impurities by hydrolysis of difluorosilicone phosphate, thereby obtaining difluorosilicone phosphate of higher purity.

[0063] In some embodiments, POF3 gas is introduced into the first mixture for reaction. The excess of POF3 gas is 5% to 30%, specifically 5%, 10%, 15%, 20%, 25%, 30%, etc., calculated based on the stoichiometric ratio of the reaction between the organosilicon alkoxide and the POF3 gas. The excess of POF3 gas can be 20%, calculated based on the stoichiometric ratio of the reaction between the organosilicon alkoxide and the POF3 gas. This can further increase the reaction rate, save raw materials, and reduce reaction costs.

[0064] Specifically, an excess of POF3 is conducive to the forward reaction, greatly improving the reaction efficiency, ensuring the complete reaction of the organosilicon salt in the reaction, improving the reaction conversion rate, and making the generated fluoride salt clean and recyclable.

[0065] In some embodiments, during the reaction of the organosilicon alkoxide and the POF3 gas, the reaction progress is monitored by NMR F spectroscopy, and the reaction is stopped after the POF3 gas and / or silicon difluorophosphate content remains unchanged. This facilitates a more complete reaction between the organosilicon alkoxide and the POF3 gas, avoids waste of raw materials and time, and improves efficiency.

[0066] In some embodiments, after the reaction of the organosilicon alkoxide and the POF3 gas is completed, at least one of the following post-processing steps is further included:

[0067] Nitrogen purge to remove POF3 gas;

[0068] filtering to remove the metal fluoride precipitate to obtain a filtrate;

[0069] The filtrate is distilled at 10° C. to 60° C. and -0.09 MPa to 0.098 MPa.

[0070] Specifically, the mixture directly obtained after the reaction of the organosilicon alkoxide and POF3 gas is purged with nitrogen to remove residual POF3 gas. The generated metal fluoride precipitate is filtered and removed to obtain a filtrate containing difluorosilyl phosphate. Under the above conditions, difluorosilyl phosphate can be separated from the organic solvent by distillation. This operation can effectively improve the purity of the obtained difluorosilyl phosphate and achieve a high yield.

[0071] In some embodiments, after the reaction of the organosilicon salt and POF3 gas is completed, the following steps are further performed in sequence: nitrogen purging the mixture directly obtained by the reaction of the organosilicon salt and POF3 gas; filtering the nitrogen-purged mixture; and distilling the filtrate obtained by filtration at 10°C to 60°C and -0.09MPa to 0.098MPa.

[0072] It is understandable that since the product prepared in the reaction system contains only excess POF3 and organic solvent, it can be removed by the above-mentioned post-treatment steps. This is not only simple to operate, but also can effectively remove impurities, so that the treated product has high purity and high yield.

[0073] In some embodiments, after the reaction is completed, nitrogen purging, filtration, and distillation are carried out in sequence, and the yield of the obtained product is ≥80%, specifically, 80.0%, 85.0%, 88.0%, 90.0%, 92.0%, 95.0%, etc. Therefore, the preparation method is suitable for mass production.

[0074] The second aspect of the present application provides a silicon difluorophosphate prepared by the aforementioned method for preparing silicon difluorophosphate. The silicon difluorophosphate has high purity and few impurities, and can be used as an electrolyte additive to effectively reduce side reactions and improve the electrochemical performance of batteries.

[0075] In some embodiments, the purity of the silicon difluorophosphate is ≥99.0%, such as 99.0%, 99.1%, 99.2%, 99.3%, 99.4%, 99.5%, 99.6%, 99.7%, 99.8%, 99.9%, etc. Therefore, when the silicon difluorophosphate is used in a battery, side reactions are reduced, effectively improving the electrochemical performance of the battery.

[0076] The embodiments of the present application are described in detail below.

[0077] Example 1:

[0078] 1. Purge nitrogen into the autoclave to maintain a nitrogen-free atmosphere, add a certain amount of organosilicon alkoxide and ethyl acetate, stir and dissolve until the mixture is uniform, measure the moisture content in the autoclave to be 5ppm, introduce phosphorus oxyfluoride gas, and react at a temperature of 30°C, a pressure of 0.4MPa, and a phosphorus oxyfluoride excess of 20%;

[0079] 2. During the reaction of the organosilicon alkoxide and phosphorus oxytrifluoride gas, the reaction progress is monitored by nuclear magnetic resonance F spectroscopy. When the content of the difluorosilyl phosphate remains unchanged, the reaction is stopped and the pressure is released;

[0080] 3. Purge with nitrogen to remove phosphorus oxytrifluoride gas, filter to remove metal fluoride, and then distill the filtrate at 25°C and -0.092 MPa to separate the organic solvent in the filtrate to obtain the product difluorosilyl phosphate.

[0081] Example 2-50

[0082] The method is the same as that in Example 1, and the specific parameters that are different are shown in Table 1.

[0083] Comparative Example 1

[0084] After adding chlorotrimethylsilane (48.7 g, 448 mmol, manufactured by TCI Corporation) as a silicon compound to a 200 mL eggplant-shaped flask with a stirrer, difluorophosphoric acid (45.7 g, 448 mmol) as a phosphoric acid compound was added dropwise at room temperature. The mixed solution was stirred at 50° C. for 6 hours under a nitrogen stream. Trimethylsilyl difluorophosphate (49.0 g, 62.7% yield) was obtained as a colorless liquid of a phosphate ester by atmospheric distillation of the reaction mixture. The purity of the trimethylsilyl difluorophosphate was 95.6%.

[0085] Performance testing:

[0086] 1. Silicon difluorophosphate structure test: Use nuclear magnetic resonance to test the structure of the product.

[0087] 2. Product Purity and Yield Testing: Gas chromatography (GC) was used for determination, using acetonitrile as the solvent, an Agilent 7890B gas chromatograph equipped with an FID detector, and a Restek® RTX-65 gas chromatograph column. The inlet temperature was 120°C, the detector temperature was 150°C, and the column temperature program was (initial 50°C, hold for 1 minute, then 5°C / min to 120°C, hold for 1 minute). The column flow rate was 1 mL / min. The test results are shown in Table 1.

[0088] Table 1

[0089]

[0090] The above test results show that the preparation of difluorosilyl phosphate by reacting organosilicon salts and POF3 gas has a fast reaction rate, mild reaction conditions, short reaction time and high reaction yield (yield ≥ 80%), high product purity, and the generated fluoride salt can be recycled with high atomic utilization.

[0091] In the description of this specification, the reference terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0092] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A method for preparing silicon difluorophosphate, characterized in that, include: Under the conditions of a pressure of 0.01 MPa to 0.6 MPa and a temperature of 5° C. to 80° C., the organosilicon alkoxide represented by formula I and an organic solvent are mixed to obtain a first mixture; and POF3 gas is introduced into the first mixture to obtain a difluorosilyl phosphate represented by formula II. Wherein, the organic solvent is selected from at least one of dichloromethane, dichloroethane, ethyl acetate, acetonitrile, diethyl ether, ethylene glycol dimethyl ether, and dimethyl carbonate; Formula I Formula II wherein R1, R2, and R3 are each independently selected from any one of a C1-C6 alkyl group, a C2-C6 alkenyl group, a C2-C6 alkynyl group, and a substituted or unsubstituted phenyl group; M is selected from any one of lithium, sodium and potassium; According to the stoichiometric ratio of the reaction between the organosilicon alkoxide and the POF3 gas, the POF3 gas is in excess of 5% to 30%.

2. The method according to claim 1, characterized in that The reaction of the organosilicon alkoxide and the POF3 gas satisfies at least one of the following conditions: The reaction temperature is 20°C to 40°C; The reaction pressure is 0.2 MPa to 0.45 MPa; The reaction time is 1 h to 6 h.

3. The method according to claim 1, characterized in that Under the condition that the water content is ≤50 ppm, the organic silicon alkoxide and the POF3 gas are reacted.

4. The method according to claim 1, wherein According to the stoichiometric ratio of the reaction between the organosilicon alkoxide and the POF3 gas, the POF3 gas is in excess of 20%.

5. The method according to claim 1, wherein The mass ratio of the organosilicon alkoxide to the organic solvent is 1:2 to 1:

8.

6. The method according to claim 1, characterized in that During the reaction of the organosilicon alkoxide and the POF3 gas, the reaction progress is monitored by nuclear magnetic resonance F spectroscopy, and the reaction is stopped after the content of the POF3 gas and / or the difluorosilyl phosphate remains unchanged.

7. The method according to any one of claims 1 to 6, characterized in that After the reaction of the organosilicon alkoxide and the POF3 gas is completed, at least one of the following steps is further included: Nitrogen purging to remove the POF3 gas; filtering to remove the metal fluoride precipitate to obtain a filtrate; The filtrate is distilled at 10° C. to 60° C. and -0.09 MPa to 0.098 MPa.

8. The method according to any one of claims 1 to 6, characterized in that R1, R2, and R3 are each independently selected from any one of a methyl group and an ethyl group.

9. The method according to claim 8, characterized in that The organosilicon alkoxide includes 、 、 , at least one of triethylsiloxylithium, triethylsiloxysodium, and triethylsiloxypotassium; The difluorosilyl phosphate comprises and At least one of .

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