Triphosphate electrolyte additive and preparation method thereof
By introducing unsaturated hydrocarbon groups into triphosphate compounds to prepare tri(vinylmethylsilyl) phosphate, the limitations of electrolyte additives in the existing technology in terms of safety and battery cycle performance are solved, and higher battery safety and electrical cycle performance are achieved. The preparation method is simple and efficient.
Patent Information
- Application Number
- CN202510903094.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-01
- Publication Date
- 2025-10-10
AI Technical Summary
Existing triphosphate electrolyte additives have limitations in improving battery safety and battery cycle performance, especially in the lack of research on the introduction of unsaturated hydrocarbon groups.
By introducing an unsaturated hydrocarbon group into a triphosphate compound, using diammonium hydrogen phosphate and 1,1,3,3-tetramethyl-1,3-divinyldisilazane as starting materials, and reacting under the synergistic action of a phase transfer catalyst and a polymerization inhibitor, tris(vinylmethylsilyl)phosphate is prepared. The process flow is simplified, recrystallization is avoided, and a high-purity product is obtained directly through distillation.
The safety performance and high-temperature electrical cycle performance of the battery are improved, and the high-voltage electrical cycle performance of the battery is improved. The preparation method is simple, with few by-products, and is suitable for industrial applications.
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Figure CN120757584A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The application belongs to the technical field of battery electrolyte additives, and particularly relates to a triphosphate electrolyte additive and a preparation method thereof. BACKGROUND
[0002] The structural formula of the tri(vinylmethylsilyl) phosphate is shown as Formula 1, and the tri(vinylmethylsilyl) phosphate is a novel triphosphate electrolyte additive. The triphosphate compound has good solubility and ionic conductivity, and when used as an electrolyte additive, can not only improve the stability of the electrolyte, improve the flowability and conductivity of the electrolyte, adjust the acid-base property of the electrolyte, but also has certain flame retardant performance and improves the safety of the battery.
[0003]
[0004] Commonly used triphosphate electrolyte additives such as tri(trimethylsilyl) phosphate have been widely used in the field of lithium battery manufacturing, and the prior art has studied the performance and preparation method of the substance. The tri(trimethylsilyl) phosphate can inhibit the capacity reduction of the battery, the P-O-Si bond therein inhibits the reaction of unreacted polymerizable compounds in the electrode, and thus can inhibit the increase of the battery resistance. When the non-aqueous electrolyte contains both a sulfonic acid lactone having an unsaturated hydrocarbon group and a tri(trimethylsilyl) phosphate compound, a low-resistance coating film can be formed on the surface of the negative electrode without reducing the high-current performance of the battery, so that the self-discharge of the battery can be greatly inhibited, and the cycle performance of the battery can be improved.
[0005] The present application aims to introduce an unsaturated hydrocarbon group into the triphosphate compound to prepare a novel electrolyte additive. SUMMARY
[0006] The present application aims to introduce an unsaturated hydrocarbon group into the triphosphate compound to prepare a novel electrolyte additive.
[0007] The technical solution adopted by the present application is a triphosphate electrolyte additive, and the key lies in that the triphosphate electrolyte additive is tri(vinylmethylsilyl) phosphate, and the structural formula is shown as Formula 1.
[0008] Formula 1,
[0009]
[0010] A method for preparing a triphosphate electrolyte additive for use in the above-mentioned triphosphate electrolyte additive. The key to the preparation method is that diammonium hydrogen phosphate and 1,1,3,3-tetramethyl-1,3-divinyldisilazane are used as starting materials, and react under the synergistic action of a phase transfer catalyst and a polymerization inhibitor to produce tris(vinylmethylsilyl)phosphate. The molar ratio of the diammonium hydrogen phosphate to 1,1,3,3-tetramethyl-1,3-divinyl is 1:1.6-2.0. The specific synthesis route is:
[0011]
[0012] Specifically, the reaction temperature is 120° C. to 160° C., and the reaction time is 3 h to 6 h.
[0013] Preferably, the phase transfer catalyst is 18-crown-6 or 15-crown-5, and the polymerization inhibitor is phenothiazine.
[0014] Furthermore, the molar amount of the phase transfer catalyst is 0.3% to 0.4% of the molar amount of diammonium hydrogen phosphate.
[0015] Furthermore, the molar ratio of the phase transfer catalyst to the polymerization inhibitor is 1:1.2-1.4.
[0016] Furthermore, the above-mentioned preparation method is specifically as follows: adding diammonium hydrogen phosphate, a phase transfer catalyst and an inhibitor to a reactor, stirring and adding 1,1,3,3-tetramethyl-1,3-divinyldisilazane dropwise, after the addition is completed, continuing to stir and heating to react, and after the reaction is completed, performing reduced pressure distillation to obtain a tris(vinylmethylsilyl)phosphate product.
[0017] It should be noted that the temperature of the above-mentioned vacuum distillation is 80°C to 120°C. During the vacuum distillation process, the above-mentioned tris(vinylmethylsilyl)phosphate product is obtained by fractionation at a top temperature of 60°C to 90°C.
[0018] Optimally, the rate of adding 1,1,3,3-tetramethyl-1,3-divinyldisilazane is 0.04 mol / min to 0.06 mol / min.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] The present invention discloses a triphosphate electrolyte additive, wherein an unsaturated hydrocarbon group is introduced into the structure of a traditional triphosphate electrolyte additive tris(trimethylsilyl)phosphate to obtain tris(vinylmethylsilyl)phosphate as shown in structural formula 1.
[0021] The preparation method of the additive is simpler, and the reaction can occur with the synergistic effect of a crown ether phase transfer catalyst and a polymerization inhibitor phenothiazine, without the aid of a reaction solvent, and after the reaction is completed, the high-purity product meeting the quality requirements of the electrolyte additive can be obtained through distillation without the purification process such as recrystallization. The synthesis route of the preparation method is simple, and the by-products are few, so that the three vinyl silicon groups of the phosphate and the silazane can be completely reacted to generate the target product instead of the mono-substituted or di-substituted by-products. It can be seen that the catalyst has high selectivity, and thus a higher overall yield is obtained, which is very suitable for industrial popularization and application.
[0022] The tris(vinylmethylsilyl) phosphate prepared in the application can be used as an electrolyte additive, can improve the safety performance of the battery, and can also make the battery have higher high-temperature electrical cycle performance. In addition, compared with the traditional tris(trimethylsilyl) phosphate, the use of the application as an electrolyte additive can also improve the high-voltage electrical cycle performance of the battery. This may be because the vinyl groups in the structure can increase the mechanical strength of the CEI film through polymerization, and the vinyl groups also have the ability to inhibit dendrite growth, thereby improving the electrical cycle performance of the battery. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1 is the nuclear magnetic hydrogen spectrum of product sample 1 of the application.
[0024] Figure 2 is the high-efficiency gas chromatograph-mass spectrum analysis spectrum of product sample 1 of the application.
[0025] Figure 3 is the high-efficiency gas chromatograph spectrum of product sample 1 of the application. DETAILED DESCRIPTION
[0026] The technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.
[0027] In the embodiments, the specific conditions not mentioned are carried out according to the conventional conditions; the reagents or instruments not mentioned by the manufacturers are all conventional products that can be obtained by market purchase.
[0028] In the embodiments, diammonium hydrogen phosphate and 1,1,3,3-tetramethyl-1,3-divinyl disilazane are used as starting materials, and the reaction occurs under the synergistic effect of a phase transfer catalyst and a polymerization inhibitor to generate tris(vinylmethylsilyl) phosphate, and the structural formula is shown as formula 1.
[0029] The specific synthetic route is:
[0030]
[0031] Example 1
[0032] The preparation method of tris(vinylmethylsilyl)phosphate in this embodiment comprises the following specific steps:
[0033] S1. At room temperature, add 1 mol of (NH4)2HPO4, 0.0035 mol of 18-crown ether-6 and 0.0027 mol of phenothiazine to the reactor, start stirring, and add 1.8 mol of 1,1,3,3-tetramethyl-1,3-divinyldisilazane dropwise at a rate of 0.05 mol / min;
[0034] After the addition of S2 and 1,1,3,3-tetramethyl-1,3-divinyldisilazane was completed, the temperature was raised to 150°C, and the reaction temperature was maintained while stirring for 4 hours.
[0035] S3. After the reaction is completed, the ammonia and unreacted 1,1,3,3-tetramethyl-1,3-divinyldisilazane in the distillation system are decompressed at room temperature with a vacuum degree of about 0.1 mmHg, and then the oil pump is decompressed at 110°C to 120°C for distillation with a top temperature of 80°C to 90°C to obtain tris(vinylmethylsilyl)phosphate product, which is recorded as product sample 1.
[0036] Example 2
[0037] The preparation method of tris(vinylmethylsilyl)phosphate in this embodiment comprises the following specific steps:
[0038] S1. At room temperature, add 1 mol of (NH4)2HPO4, 0.0030 mol of 18-crown ether-6 and 0.0021 mol of phenothiazine to the reactor, start stirring, and add 1.6 mol of 1,1,3,3-tetramethyl-1,3-divinyldisilazane dropwise at a rate of 0.06 mol / min;
[0039] After the addition of S2 and 1,1,3,3-tetramethyl-1,3-divinyldisilazane was completed, the temperature was raised to 160°C, and the reaction temperature was maintained while stirring for 3 hours;
[0040] S3. After the reaction is completed, the ammonia and unreacted 1,1,3,3-tetramethyl-1,3-divinyldisilazane in the distillation system are decompressed at room temperature with a vacuum degree of about 0.5 mmHg, and then the oil pump is decompressed at 100°C to 100°C for distillation, and the top temperature is 70°C to 80°C to obtain tris(vinylmethylsilyl)phosphate product, which is recorded as product sample 2.
[0041] Example Three
[0042] The preparation method of tris(vinylmethylsilyl) phosphate in this example, the specific steps are:
[0043] S1, at room temperature, 1 mol of (NH4)2HPO4, 0.0040 mol of 18-crown-6 and 0.0033 mol of phenothiazine were added to the reactor, and stirring was started. 2.0 mol of 1,1,3,3-tetramethyl-1,3-divinyl disilazane was added at a rate of 0.04 mol / min;
[0044] S2, after the addition of 1,1,3,3-tetramethyl-1,3-divinyl disilazane was completed, the temperature was raised to 120°C, the stirring was continued and the reaction temperature was maintained, and the reaction was carried out for 6h;
[0045] S3, after the reaction was completed, the ammonia gas and unreacted 1,1,3,3-tetramethyl-1,3-divinyl disilazane in the system were distilled at room temperature under reduced pressure, the vacuum degree was about 1.0 mmHg, then the oil pump was used to reduce the pressure and distill at 80°C-90°C, the top temperature was 60°C-65°C to obtain tris(vinylmethylsilyl) phosphate product, which was marked as product sample 3.
[0046] Example Four
[0047] The preparation method of tris(vinylmethylsilyl) phosphate in this example, the specific steps are:
[0048] S1, at room temperature, 1 mol of (NH4)2HPO4, 0.0038 mol of 15-crown-5 and 0.0028 mol of phenothiazine were added to the reactor, and stirring was started. 1.7 mol of 1,1,3,3-tetramethyl-1,3-divinyl disilazane was added at a rate of 0.055 mol / min;
[0049] S2, after the addition of 1,1,3,3-tetramethyl-1,3-divinyl disilazane was completed, the temperature was raised to 130°C, the stirring was continued and the reaction temperature was maintained, and the reaction was carried out for 5h;
[0050] S3, after the reaction was completed, the ammonia gas and unreacted 1,1,3,3-tetramethyl-1,3-divinyl disilazane in the system were distilled at room temperature under reduced pressure, the vacuum degree was about 0.8 mmHg, then the oil pump was used to reduce the pressure and distill at 90°C-100°C, the top temperature was 65°C-70°C to obtain tris(vinylmethylsilyl) phosphate product, which was marked as product sample 4.
[0051] Comparative Example One
[0052] The preparation is the same as in Example 1, except that in S1 step, the phase transfer catalyst used is not 18-crown-6 or 15-crown-5, but 0.0050 mol of tetrabutylammonium bromide; the reaction temperature of S3 step is not changed, but GC is used to monitor the reaction progress, and the reaction is ended when the product concentration does not change; the subsequent preparation process is the same as in Example 1, and the reference substance 1 is prepared.
[0053] Comparative Example 2
[0054] The preparation is the same as in Example 1, except that in S1 step, the polymerization inhibitor used is not phenothiazine, but 0.0030 mol of hydroquinone; the reaction temperature of S3 step is not changed, but GC is used to monitor the reaction progress, and the reaction is ended when the product concentration does not change; the subsequent preparation process is the same as in Example 1, and the reference substance 2 is prepared.
[0055] Comparative Example 3
[0056] The preparation process is as follows:
[0057] S1, 1 mol of (NH4)2HPO4 is dissolved in 500 mL of water to prepare a (NH4)2HPO4 solution, and 1.8 mol of 1,1,3,3-tetramethyl-1,3-divinyl disilazane is dissolved in 800 mL of toluene to prepare a 1,1,3,3-tetramethyl-1,3-divinyl disilazane toluene solution;
[0058] S2, at room temperature, the (NH4)2HPO4 solution, 0.0035 mol of 18-crown-6 and 0.0027 mol of phenothiazine are added to the reactor, and stirring is started, and the 1,1,3,3-tetramethyl-1,3-divinyl disilazane toluene solution is added in 5 portions;
[0059] S2, after the addition of 1,1,3,3-tetramethyl-1,3-divinyl disilazane is completed, the temperature is raised to 150°C, and the stirring is continued and the reaction temperature is maintained, and GC is used to monitor the reaction progress, and the reaction is ended when the product concentration does not change;
[0060] S3 step is the same as in Example 1, and the reference substance 3 is prepared.
[0061] Analysis and testing
[0062] The product prepared by the present application is analyzed by nuclear magnetic hydrogen spectrum and high-efficiency gas chromatography-mass spectrometry, and it is confirmed that the product sample conforms to the structural characteristics of tris (vinylmethylsilyl) phosphate, and the test spectrum is shown in Figures 1-2 .
[0063] The present application also uses high-efficiency gas chromatography to test the purity of the product sample, and the yield is calculated by the following formula, and the results are shown in Table 1 and Figure 3The impurity analysis results of sample 1 are shown in Table 2.
[0064] The yield calculation formula is:
[0065] Product yield = actual weight (g) of the obtained product / theoretical obtained amount (g) calculated based on the amount of (NH4)2HPO4 used × 100%.
[0066] Table 1: Summary table of purity and yield results
[0067] Test sample Purity (%) Polymerization inhibitor (ppm) Yield (%) Product sample 1 99.73 4 93.8 Product sample 2 99.68 6 92.9 Product sample 3 99.72 7 92.5 Product sample 4 99.65 8 93.1 Control 1 78.26 1 62.1 Control 2 66.31 8 56.2 Control 3 71.3 6 46.3
[0068] Table 2: Impurity analysis results of product sample 1
[0069]
[0070]
[0071] As can be seen from the results in Table 1, the purity of the product prepared by the application is more than 99.65%, and the polymerization inhibitor is less than 10 ppm, so that the quality requirements as an electrolyte additive can be met without the need for purification processes such as recrystallization; the product yield can reach more than 90%, the yield is very high, and the preparation method is suitable for industrialization and application.
[0072] Application example
[0073] Product sample 1 is added to the electrolyte of a lithium battery as application sample 1, the electrolyte without any additive is used as a blank example, and the electrolyte with tris(trimethylsilyl) phosphate is used as application comparison 1, wherein the addition amount of the electrolyte additive is 1% of the total mass of the electrolyte, and the electrolyte is used to make a lithium battery with a capacity of 1000 mAh for battery application test, with ternary material lithium as the positive electrode material and graphite as the negative electrode.
[0074] (1) Battery electrical safety test
[0075] 1. Normal temperature external short circuit
[0076] After the battery is fully charged, it is placed in an environment of 20℃±5℃, and after the surface temperature of the battery reaches 20℃±5℃, it is placed for another 30 min, then the positive and negative electrodes of the battery are connected with wires, and the total external resistance is ensured to be 80mΩ±20mΩ, the battery temperature change is monitored during the test, the battery should not catch fire, explode, and the maximum temperature should not exceed 150℃.
[0077] 2. High temperature external short circuit
[0078] After the battery is fully charged, it is placed in an environment of 55°C ± 5°C, and after the surface temperature of the battery reaches 55°C ± 5°C, it is placed for another 30 min. Then the positive and negative terminals of the battery are connected with wires, and the total external resistance is ensured to be 80 mΩ ± 20 mΩ. During the test, the temperature change of the battery is monitored, and the battery should not catch fire, explode, and the maximum temperature should not exceed 150°C.
[0079] 3. Overcharge
[0080] After the battery is fully discharged, it is first charged to a test voltage of 4.6V with a charging current of 3CA, and then it is charged at a constant voltage of the test voltage. The battery should not catch fire, explode.
[0081] 4. Forced discharge
[0082] After the battery is fully discharged, it is reverse charged at a current of 1CA for 90 min. The battery should not catch fire, explode.
[0083] The test results of the battery electrical safety test are shown in Table 3:
[0084] Table 3: Test results of battery electrical safety test
[0085] Sample Normal temperature external short circuit High temperature external short circuit Overcharge Forced discharge Application sample 1 Normal Normal Normal Normal Application comparison 1 Normal Normal Normal Normal Blank case Fire Temperature over 150°C Fire ——
[0086] As can be seen from the results in Table 3, in the test group of lithium battery electrolyte with bis-fluoroethylene carbonate, no external short circuit occurred, and overcharge was normal, indicating that the addition of bis-fluoroethylene carbonate can effectively enhance the electrical safety performance of lithium batteries.
[0087] (B) Battery environmental safety test
[0088] 1. Low pressure
[0089] After the battery is fully charged, it is placed in a vacuum box at 20°C, and the pressure in the box is reduced to 11.6 kPa by vacuumizing for 6 h. The battery should not catch fire, explode, or leak.
[0090] 2. Temperature cycling
[0091] After the battery is fully charged, it is placed in a temperature-controlled box at 20°C ± 5°C and subjected to the following steps:
[0092] a) Place the sample in an experimental box at a temperature of 75°C ± 2°C for 6 h;
[0093] b) Then reduce the temperature of the experimental box to -40°C ± 2°C and maintain for 6 h, with a temperature conversion time of not more than 30 min;
[0094] c) Again, increase the temperature of the experimental box to 75°C ± 2°C, with a temperature conversion time of not more than 30 min
[0095] d) Repeat steps a) to c) for a total of 10 cycles;
[0096] The battery should not catch fire, explode or leak.
[0097] 3. Acceleration shock
[0098] After fully charging the battery, fix it on the shock table and perform a half-sine pulse shock test. In the first 3ms, the minimum average acceleration is 75g. n , peak acceleration is 150g n ±25g n , the pulse duration is 6ms±1ms, and the battery is subjected to three acceleration shocks in each direction. The battery should not catch fire, explode or leak.
[0099] 4. Fall
[0100] After fully charging the battery, drop it from a height of 1m onto a concrete slab for a total of four drop tests. The battery should not catch fire or explode.
[0101] 5. Extrusion
[0102] After the battery is fully charged, place it in two planes and squeeze it perpendicular to the direction of the plates. Apply a squeezing force of 13.0kN±0.78kN between the two plates. Stop the squeezing test once the pressure reaches the maximum value. No external short circuit should occur in the battery during the test.
[0103] 6. Thermal abuse
[0104] After fully charging the battery, place it in a test chamber. Heat the chamber at a rate of (5±2)℃ / min. When the temperature inside the chamber reaches 130℃±2℃, keep the temperature constant for 30 minutes. The battery should not catch fire or explode.
[0105] 7. Combustion Injection
[0106] After fully charging the battery, place it on the wire mesh of the test fixture. If the battery slips during the test, use a single metal wire to fix the battery sample to the wire mesh. If this does not happen, do not bundle the battery. Heat the battery with a flame and stop heating when the following three situations occur: a) the battery explodes; b) the battery is completely burned; c) heating is continued for 30 minutes, but the battery does not catch fire or explode; after the test, the components of the battery (except for dust-like products) or the battery as a whole shall not penetrate the aluminum mesh.
[0107] The test results of the battery environmental safety test are shown in Table 4:
[0108] Table 4: Test results of battery environmental safety test
[0109] Sample Low air pressure Temperature cycle Acceleration impact Drop Crushing Thermal abuse Combustion injection Application sample 1 Normal Normal Normal Normal Normal No change Normal Application comparison 1 Normal Normal Normal Normal Normal No change Normal Blank case Normal Leakage Leakage Normal Short circuit Explosion Explosion
[0110] From the results in Table 4, it can be seen that adding tris(trimethylsilyl)phosphate and tris(vinylmethylsilyl)phosphate to the lithium battery electrolyte can effectively enhance the battery environmental safety performance of the lithium battery.
[0111] (3) High voltage and high temperature electrical cycle performance test
[0112] High-voltage electrical cycle performance test: The test environment temperature is 25℃±2℃. The battery is charged to 4.6V at a constant current of 1C, then charged to a current of 0.05C while maintaining the voltage at 4.6V, and then discharged to 3.0V at a constant current of 1C. This is the first cycle.
[0113] High temperature electrical cycle performance test: The test environment temperature is 60℃±2℃. The battery is charged to 4.2V at a constant current of 1C, then charged to a current of 0.05C while maintaining the voltage at 4.2V, and then discharged to 3.0V at a constant current of 1C. This is the first cycle.
[0114] According to the above cycle conditions, charge / discharge cycles were performed for 100 times, 300 times and 500 times, respectively, and the capacity retention rates of the batteries after 100 cycles, 300 cycles and 500 cycles were calculated, respectively. The results are shown in Table 5.
[0115] Table 5: Summary of battery performance test results
[0116]
[0117] As can be seen from the results in Table 5, application comparison 1 can improve the high-temperature electrical cycle performance of the electrolyte, but the effect of improving the high-voltage electrical cycle performance of the electrolyte is not as significant as that of tris(vinylmethylsilyl)phosphate products.
[0118] The battery after 500 cycles was disassembled, and the electrodes were soaked in dimethyl carbonate to remove the residual electrolyte. After vacuum drying (60 ° C, 12 h), the electrodes were cut into small pieces (about 1 × 1 cm 2 ), the elastic modulus of the electrode was measured by nanoindentation method, and the uncycled electrode was used as the initial control. The results are shown in Table 6.
[0119] Table 6: Changes in the elastic modulus of the electrode
[0120]
[0121]
[0122] As can be seen from the results in Table 6, after the lithium battery was cycled at high temperature and high pressure for 500 times, the elastic modulus of the positive and negative electrodes of the application samples using the additive of the present invention decreased at the lowest rate, indicating that the use of the tris(vinylmethylsilyl)phosphate of the present invention as an electrolyte additive can improve the mechanical strength of the electrode.
Claims
1. A triphosphate electrolyte additive, characterized in that: The triphosphate electrolyte additive is tri(vinylmethylsilyl)phosphate, and its structural formula is shown in Formula 1.
2. A method for preparing a triphosphate electrolyte additive, for preparing the triphosphate electrolyte additive according to claim 1, characterized in that: The preparation method uses diammonium hydrogen phosphate and 1,1,3,3-tetramethyl-1,3-divinyldisilazane as starting materials, reacts under the synergistic action of a phase transfer catalyst and a polymerization inhibitor to generate tris(vinylmethylsilyl)phosphate, wherein the molar ratio of diammonium hydrogen phosphate to 1,1,3,3-tetramethyl-1,3-divinyl is 1:1.6-2.
0. The specific synthesis route is:
3. The method for preparing a triphosphate electrolyte additive according to claim 2, wherein: The reaction temperature is 120°C to 160°C, and the reaction time is 3h to 6h.
4. The method for preparing a triphosphate electrolyte additive according to claim 2, wherein: The phase transfer catalyst is 18-crown-6 or 15-crown-5, and the polymerization inhibitor is phenothiazine.
5. The method for preparing a triphosphate electrolyte additive according to claim 2, characterized in that: The molar amount of the phase transfer catalyst is 0.3% to 0.4% of the molar amount of diammonium hydrogen phosphate.
6. The method for preparing a triphosphate electrolyte additive according to claim 2, characterized in that: The molar ratio of the phase transfer catalyst to the polymerization inhibitor is 1:1.2-1.
4.
7. The method for preparing a triphosphate electrolyte additive according to claim 2, characterized in that: The preparation method specifically comprises the following steps: adding diammonium hydrogen phosphate, a phase transfer catalyst and a polymerization inhibitor into a reactor, stirring and dropwise adding 1,1,3,3-tetramethyl-1,3-divinyldisilazane; after the dropwise addition is completed, continuing stirring and heating to carry out the reaction; and performing reduced pressure distillation after the reaction is completed to obtain a tris(vinylmethylsilyl)phosphate product.
8. The method for preparing a triphosphate electrolyte additive according to claim 7, characterized in that: The temperature of the reduced pressure distillation is 80° C. to 120° C. During the reduced pressure distillation process, the tris(vinylmethylsilyl)phosphate product is obtained by fractionation at a top temperature of 60° C. to 90° C.
9. The method for preparing a triphosphate electrolyte additive according to claim 7, characterized in that: The rate of dropwise addition of 1,1,3,3-tetramethyl-1,3-divinyldisilazane is 0.04 mol / min to 0.06 mol / min.