Method for measuring content of 1-propyl cyclic phosphoric anhydride in lithium ion battery electrolyte
Through anion chromatography and single-standard correction methods, the instability problem of determining the content of 1-propyl cyclic phosphate anhydride in the lithium-ion battery electrolyte was solved, and rapid and accurate measurement was achieved, ensuring the quality of the lithium-ion battery.
Patent Information
- Application Number
- CN202310843179.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-11
- Publication Date
- 2025-01-14
AI Technical Summary
The prior art is difficult to accurately determine the content of 1-propyl cyclic phosphoric anhydride in lithium-ion battery electrolytes, especially due to its hydrolyzing characteristics and the lack of characteristic peaks in gas chromatography, resulting in unstable and inaccurate measurements.
By using anion chromatography, the samples to be tested and standard solutions were prepared, and acetonitrile water leaching solution of Na2CO3 and NaHCO3 and concentrated sulfuric acid regeneration solution were used. Combined with a single standard calibration method, 1-propyl cyclic phosphate anhydride was calculated based on peak area and time. content.
It realizes fast, accurate and stable 1-propyl cyclic phosphate anhydride content measurement, improves the measurement efficiency, and provides reliable guarantee for the quality of lithium-ion batteries.
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Figure CN119310219A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of lithium battery electrolyte component determination, and in particular to a method for determining the content of additive 1-propyl cyclic phosphoric anhydride. Background Art
[0002] As a new type of additive, 1-propyl cyclic phosphoric anhydride has been widely used in lithium battery electrolytes in recent years. This additive can effectively improve the high temperature cycle performance and storage performance of lithium batteries.
[0003] 1-propyl cyclic phosphoric anhydride has active chemical properties and is easily hydrolyzed, and its hydrolysis characteristic peak exists on anion chromatography. However, due to the complex formula in the electrolyte, after 1-propyl cyclic phosphoric anhydride is added to the electrolyte, the peak area of the hydrolysis characteristic peak is unstable and tends to increase slowly, making it difficult to accurately measure. Due to the special chemical properties of 1-propyl cyclic phosphoric anhydride, its characteristic peak cannot appear on gas chromatography, so it cannot be quantitatively analyzed by gas chromatography. Summary of the invention
[0004] The technical problem to be solved by the present invention is to provide a method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte. The method can quickly and accurately detect the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte and has good stability.
[0005] To solve the above problems, the technical solution adopted by the present invention is: the determination of the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte comprises the following steps: 1. preparing a sample solution to be tested: taking a lithium ion battery electrolyte to be tested, and performing a pretreatment, the steps comprising: adding a pretreatment solution, the pretreatment solution being a nitric acid aqueous solution with a mass fraction of 0.3% to 0.5%, heating at 60°C to 100°C for 10 to 60 minutes, and diluting with water after the pretreatment to obtain a sample solution to be tested; 2. preparing a standard solution: taking a 1-propyl cyclic phosphoric anhydride diethyl carbonate solution, adding a simple formula lithium ion battery electrolyte, the simple formula lithium ion battery electrolyte only contains an organic solvent and lithium hexafluorophosphate, stirring evenly to obtain a standard solution mother liquor, and the standard solution mother liquor is refrigerated and allowed to stand; taking the standard solution mother liquor, and mixing with the preparation The same pretreatment steps as those for preparing the sample solution to be tested are followed, and then water is added to dilute the solution to obtain a standard solution, wherein the concentration of 1-propyl cyclic phosphoric anhydride in the standard solution is the theoretical value of the concentration of 1-propyl cyclic phosphoric anhydride in the sample solution to be tested ±3ppm; the theoretical value usually refers to the concentration value that should be achieved after production or dilution according to the formula requirements; 3. An anion chromatograph is used, and the instrument conditions include: the eluent is an acetonitrile-water system with Na2CO3 and NaHCO3 contents of 2.4mmol / L to 3.6mmol / L, wherein the volume ratio of water to acetonitrile is 3:1; concentrated sulfuric acid is used as the regeneration solution; the sample solution to be tested and the standard solution are measured separately, and the 1-propyl cyclic phosphoric anhydride content in the lithium-ion battery electrolyte to be tested is obtained by single-standard calibration according to the following formula according to the peak time and peak area;
[0006]
[0007] X is the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte to be tested;
[0008] A2 is the peak area of 1-propyl cyclic phosphoric anhydride in the sample solution to be tested;
[0009] A1 is the peak area of 1-propyl cyclic phosphoric anhydride in the standard solution;
[0010] C2 is the content of 1-propyl cyclic phosphoric anhydride in the standard solution, ppm;
[0011] B is the dilution factor of the lithium-ion battery electrolyte to be tested when preparing the sample solution to be tested;
[0012] 10000 is a constant.
[0013] Furthermore, the content of 1-propyl cyclic phosphoric anhydride in the aforementioned lithium-ion battery electrolyte is determined, wherein the eluent preparation method includes: first preparing an aqueous solution with a Na2CO3 and NaHCO3 content of 2.4 mmol / L to 3.6 mmol / L, filtering it with a 0.45 μm filter membrane, and then mixing it with acetonitrile filtered with a 0.45 μm filter membrane in a volume ratio of 3:1, and then ultrasonically degassing it for later use.
[0014] Furthermore, in the aforementioned determination of the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte, the mother liquor of the standard solution is refrigerated and allowed to stand at 0°C to 5°C after preparation.
[0015] Furthermore, in the aforementioned determination of the content of 1-propyl cyclic phosphoric anhydride in the lithium-ion battery electrolyte, the heating temperature in the pretreatment step is 90°C.
[0016] Further, the determination of the content of 1-propyl cyclic phosphoric anhydride in the aforementioned lithium ion battery electrolyte, wherein, when preparing the standard solution, the specific preparation steps of the standard solution mother liquor include: taking (0.6±0.05) g of 1-propyl cyclic phosphoric anhydride diethyl carbonate solution with a mass fraction of 47% to 53% in a 250 ml pp bottle, adding the simplified formula lithium ion battery electrolyte to (100±5) g, stirring evenly to obtain the standard solution mother liquor. The 1-propyl cyclic phosphoric anhydride diethyl carbonate solution was obtained by purchase.
[0017] Furthermore, in the aforementioned determination of the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte, the organic solvent in the simple formula lithium ion battery electrolyte is selected from one of diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate, and ethyl methyl carbonate.
[0018] Furthermore, the determination of the content of 1-propyl cyclic phosphoric anhydride in the aforementioned lithium ion battery electrolyte, wherein the specific steps for preparing the sample solution to be tested include: taking (1±0.05) g of the lithium ion battery electrolyte to be tested in a 250 ml pp bottle, adding the pretreatment solution to (10±0.5) g, closing the lid and heating in an oven, and then adding water to (100±5) g to obtain the sample solution to be tested.
[0019] Furthermore, in the determination of the content of 1-propyl cyclic phosphoric anhydride in the aforementioned lithium-ion battery electrolyte, the pretreatment solution is a 0.5% nitric acid aqueous solution. A nitric acid aqueous solution with a concentration that is too high will damage the chromatographic column, and a nitric acid aqueous solution with a concentration that is too low will greatly prolong the heating time during the pretreatment process and affect the peak effect.
[0020] Furthermore, in the aforementioned determination of the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte, the concentration of lithium hexafluorophosphate in the simplified formula lithium ion battery electrolyte is (13±5)%.
[0021] The advantages of the present invention are simple steps, convenience and speed, short detection time, high accuracy and good stability, which greatly improves the efficiency of determining 1-propyl cyclic phosphoric anhydride in lithium ion battery electrolyte and provides reliable guarantee for the quality of lithium ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 It is the chromatogram of the test substance 1-propyl cyclic phosphoric anhydride in Example 1, and the shaded part in the figure is the peak of 1-propyl cyclic phosphoric anhydride.
[0023] Figure 2 It is the chromatogram of the test substance 1-propyl cyclic phosphoric anhydride in Example 2, and the shaded part in the figure is the peak of 1-propyl cyclic phosphoric anhydride.
[0024] Figure 3 It is the chromatogram of the test substance 1-propyl cyclic phosphoric anhydride in Example 3, and the shaded part in the figure is the peak of 1-propyl cyclic phosphoric anhydride.
[0025] Figure 4 It is the chromatogram of the test substance 1-propyl cyclic phosphoric anhydride in Example 4, and the shaded portion in the figure is the peak of 1-propyl cyclic phosphoric anhydride.
[0026] Figure 5 It is the chromatogram of the test substance 1-propyl cyclic phosphoric anhydride in Example 5, and the shaded part in the figure is the peak of 1-propyl cyclic phosphoric anhydride.
[0027] Figure 6 It is a curve of the unit concentration peak area of 1-propyl cyclic phosphoric anhydride corresponding to different heating times during the pretreatment process in Example 6.
[0028] Figure 7 It is a curve of the unit concentration peak area of 1-propyl cyclic phosphoric anhydride corresponding to different days under the two pretreatment methods. DETAILED DESCRIPTION
[0029] The determination of the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte of the present invention is further described in detail below in conjunction with preferred embodiments.
[0030] Example 1: Take a lithium ion battery electrolyte to be tested, and the content of 1-propyl cyclic phosphoric anhydride in the standard formula of the lithium ion battery electrolyte to be tested is 3000±30ppm.
[0031] The instruments and reagents involved in the assay are shown in Table 1.
[0032] Table 1:
[0033] name Specifications / Models 1 Anion Chromatography Thermo--ICS 2 Anion chromatography columns Shodex SI-904E(4*250mm) 3 Electronic balance Graduation value 0.0001g 4 Sodium carbonate Reference reagents 5 Sodium bicarbonate Reference reagents 6 Acetonitrile Chromatographic pure 7 Nitric acid Premium Pure 8 Ultrapure water Meets GB-6682 Grade 1 water specifications
[0034] Preparation of eluent: Na2CO3 and NaHCO3 in aqueous solution with contents of 3.6 mmol / L are filtered through a 0.45 μm filter membrane, and then mixed with acetonitrile filtered through a 0.45 μm filter membrane at a volume ratio of 3:1, and then ultrasonically degassed for later use.
[0035] Preparation of 1# test sample solution: Take 1.023g of lithium-ion battery electrolyte into a 250ml PP bottle, add 0.5% nitric acid aqueous solution to 10g in the PP bottle, put it into a 90°C oven and heat it for 1h, add 102.133g of ultrapure water after cooling, and obtain 1# test sample solution.
[0036] The eluent and the 1# sample solution were connected to the anion chromatograph respectively. The anion chromatogram is shown in Figure 1 As shown, it was found that: there were many interfering peaks near the peak of the substance to be tested, which could not be separated from the chromatographic peak of the substance to be tested, and therefore could not be measured.
[0037] Example 2: In this embodiment, the eluent is re-prepared, and the remaining instruments and reagents are the same as those in Example 1. The 1# sample solution to be tested is also tested.
[0038] Preparation of eluent: Na2CO3 and NaHCO3 in aqueous solution with contents of both 2.4 mmol / L were filtered through a 0.45 μm filter membrane, and then mixed with acetonitrile filtered through a 0.45 μm filter membrane at a volume ratio of 3:1, and then ultrasonically degassed for later use.
[0039] The eluent and the 1# sample solution were connected to the anion chromatograph respectively. The anion chromatogram is shown in Figure 2 As shown, it was found that the change in the concentration of the eluent caused the peak of the substance to be tested to be separated from the interference peak, but the separation effect was not obvious compared with Example 1, so it was still impossible to measure.
[0040] Example 3: In this example, the anion chromatography column is changed compared with Example 1 and Example 2. The instruments and reagents involved in the determination process are shown in Table 2.
[0041] Table 2:
[0042] name Specifications / Models 1 Anion Chromatography Thermo-ICS 2 Anion chromatography columns Thermo AS22(4*250mm) 3 Electronic balance Graduation value 0.0001g 4 Sodium carbonate Reference reagents 5 Sodium bicarbonate Reference reagents 6 Acetonitrile Chromatographic pure 7 Nitric acid Premium Pure 8 Ultrapure water Meets GB-6682 Grade 1 water specifications
[0043] Preparation of eluent: Na2CO3 and NaHCO3 in aqueous solution with contents of both 2.4 mmol / L were filtered through a 0.45 μm filter membrane, and then mixed with acetonitrile filtered through a 0.45 μm filter membrane at a volume ratio of 3:1, and then ultrasonically degassed for later use.
[0044] The eluent and the 1# sample solution were connected to the anion chromatograph respectively. The anion chromatogram is shown in Figure 3As shown, it was found that: the chromatographic column used was Thermo AS22 (4*250 mm), and under the conditions of the eluent described in this example, 1-propyl cyclic phosphoric anhydride and the interference peak were effectively separated. Therefore, under the conditions of this example, 1-propyl cyclic phosphoric anhydride can be quantified.
[0045] Example 4: In this example, the eluent is newly prepared relative to that in Example 3, and the remaining instruments and reagents are the same as those in Example 3. The 1# sample solution to be tested is also tested.
[0046] Preparation of eluent: Na2CO3 and NaHCO3 in aqueous solution with contents of 3.6 mmol / L are filtered through a 0.45 μm filter membrane, and then mixed with acetonitrile filtered through a 0.45 μm filter membrane at a volume ratio of 3:1, and then ultrasonically degassed for later use.
[0047] The eluent and the 1# sample solution were connected to the anion chromatograph respectively. The anion chromatogram is shown in Figure 4 As shown, it was found that: when the concentration of the eluent was increased, there was still no interfering peak near the target peak, and the measurement time was effectively shortened. Compared with Example 3, the retention time of 1-propyl cyclic phosphoric anhydride was reduced from 16.617 min in Example 3 to 12.483 min in this example, and the duration of the entire sample was also shortened from 30 min in Example 3 to 20 min in this example.
[0048] Example 5: In this example, sulfuric acid was used as the pretreatment solution to prepare the 2# sample solution to be tested to check the peak effect. The instruments and reagents used are shown in Table 3, and the eluent was the same as that prepared in Example 4.
[0049] Table 3:
[0050] name Specifications / Models 1 Anion Chromatography Thermo-ICS 2 Anion chromatography columns Thermo AS22(4*250mm) 3 Electronic balance Graduation value 0.0001g 4 Sodium carbonate Reference reagents 5 Sodium bicarbonate Reference reagents 6 Acetonitrile Chromatographic pure 7 sulfuric acid Premium Pure 8 Ultrapure water Meets GB-6682 Grade 1 water specifications
[0051] Preparation of 2# test sample solution: Take 1.014g of the lithium-ion battery electrolyte to be tested into a 250ml PP bottle, add 10.132g of 0.5% sulfuric acid solution into the PP bottle, heat it in a 90°C oven for 1h, add 91.228g of ultrapure water after cooling, and obtain 2# test sample solution.
[0052] The eluent and the 2# sample solution were connected to the anion chromatograph respectively. The anion chromatogram is shown in Figure 5 As shown, it was found that after pre-treatment with sulfuric acid, the target peak was followed by an interference peak, which seriously affected the quantification of 1-propyl cyclic phosphoric anhydride.
[0053] Example 6: In this example, 3# to 10# sample solutions to be tested were prepared, and the heating time in the pretreatment process of 3# to 10# sample solutions to be tested was successively prolonged.
[0054] Preparation of the lithium-ion battery electrolyte sample to be tested: weigh 0.6005g of 50% 1-propyl cyclic phosphoric anhydride diethyl carbonate solution in a 250ml PP bottle, add a simple formula electrolyte containing only organic solvent and lithium hexafluorophosphate to 100.0821g, then the concentration of the lithium-ion battery electrolyte sample to be tested is 3000ppm. The 50% 1-propyl cyclic phosphoric anhydride diethyl carbonate solution is purchased.
[0055] The preparation process of 3#~10# test sample solutions is as follows: take (1±0.05)g of the lithium-ion battery electrolyte sample to be tested into a 250ml PP bottle, add (10±0.5)g of 0.5% nitric acid solution into the PP bottle, put it into a 90°C oven for heating, and after cooling, add (90±5)g of ultrapure water to obtain 3#~10# test sample solutions.
[0056] In the preparation process of 3#~10# sample solutions to be tested, the heating time in the oven is 10min, 20min, 25min, 30min, 35min, 40min, 45min and 50min respectively.
[0057] Under the same eluent conditions as in Example 4, the 3# to 10# sample solutions were tested. The test results are shown in Table 4. Figure 6 Shown is a graph of heating time versus peak area per unit concentration.
[0058] Table 4:
[0059]
[0060] Theoretical concentration = sample weight * 3000ppm / dilution factor.
[0061] From the change of unit concentration peak area in Table 4, we can see that the unit concentration peak area remains almost unchanged after 30 minutes. Therefore, it can be obtained that the measurement results are stable when heated at 90°C for 30 minutes or more.
[0062] Example 7: In this example, 11# to 17# sample solutions to be tested were prepared with nitric acid as pretreatment, and 18# to 24# sample solutions to be tested were prepared without nitric acid as pretreatment.
[0063] Preparation of 11#~17# test sample solutions: Take about 1g of the lithium-ion battery electrolyte to be tested and put it into a 250ml PP bottle on the 0th, 1st, 3rd, 5th, 7th, 9th and 11th day, add 0.5% nitric acid aqueous solution to the PP bottle to about 10g, put it in a 90℃ oven and heat it for about 30min, then add about 90g of ultrapure water to prepare sample 11#-17# test sample solutions. The specific mass of reagents added during the preparation process is shown in Table 5.
[0064] Preparation of 18#~24# test sample solutions: Take about (1±0.05)g of the lithium-ion battery electrolyte to be tested and put it into a 250ml PP bottle on the 0th, 1st, 3rd, 5th, 7th, 9th and 11th day respectively, add ultrapure water to the PP bottle to about 10g, put it in a 90℃ oven and heat it for about 70min, then add about 90g of ultrapure water to prepare sample 18#-24# test sample solutions.
[0065] Table 5:
[0066]
[0067] Theoretical concentration = sample weight * 3000ppm / dilution factor.
[0068] Figure 7 It can be seen intuitively that the peak area per unit concentration is stable when the pretreatment is performed with nitric acid solution, while the peak area per unit concentration varies greatly when the pretreatment is performed without adding nitric acid, that is, the stability is poor. Therefore, the stability of the determination method of the present invention is much greater than the determination method without adding nitric acid in the pretreatment, and the time required for the determination is greatly shortened.
[0069] Embodiment 8:
[0070] Preparation of sample solution to be tested:
[0071] The 25# sample to be tested is a self-prepared lithium-ion battery electrolyte containing 1031 ppm of 1-propyl cyclic phosphoric anhydride, and the electrolyte components include lithium hexafluorophosphate, propylene carbonate, propyl propionate, vinyl sulfate, and ethyl acetate.
[0072] The 26# sample to be tested is a self-prepared lithium-ion battery electrolyte containing 1974 ppm of 1-propyl cyclic phosphoric anhydride, and the electrolyte components include lithium hexafluorophosphate, dimethyl carbonate, propyl propionate, and vinyl sulfate.
[0073] The 27# sample to be tested is a self-prepared lithium-ion battery electrolyte containing 2997ppm of 1-propyl cyclic phosphoric anhydride. The electrolyte components include lithium hexafluorophosphate, dimethyl carbonate, ethylene carbonate, triphenyl phosphite, and 1,3-propane sultone.
[0074] The 28# sample to be tested is the electrolyte to be tested produced in the workshop, in which the theoretical concentration value of 1-propyl cyclic phosphoric anhydride is (2000±300) ppm.
[0075] The 29# sample to be tested is the electrolyte to be tested produced in the workshop, in which the theoretical concentration value of 1-propyl cyclic phosphoric anhydride is (3000±200) ppm.
[0076] Pre-processing specific process:
[0077] Take (1±0.05) g of the lithium-ion battery electrolyte sample to be tested into a 250 ml PP bottle, add (10±0.5) g of 0.5% nitric acid solution into the PP bottle, heat it in a 90°C oven, and add (90±5) g of ultrapure water after cooling. The specific weighing values are shown in Table 6.
[0078] Preparation of eluent: An aqueous solution containing 3.6 mmol / L of Na2CO3 and NaHCO3 was filtered through a 0.45 μm filter membrane, and then mixed with acetonitrile filtered through a 0.45 μm filter membrane at a volume ratio of 3:1, and then ultrasonically degassed for later use.
[0079] Simple formula for preparation of lithium-ion battery electrolyte: Take (15±2) g of lithium hexafluorophosphate and add diethyl carbonate to (100±5) g.
[0080] Preparation of standard solution: weigh 0.601g of 50% 1-propyl cyclic phosphoric anhydride diethyl carbonate solution into a 250ml PP bottle, add a simple formula electrolyte containing only organic solvent and lithium hexafluorophosphate to 100.082g, and the concentration of the standard solution mother liquor is 3000ppm. The 50% 1-propyl cyclic phosphoric anhydride diethyl carbonate solution is purchased from the market.
[0081] Weigh 1.013g of the standard solution mother liquor into a 250ml PP bottle, add 10.131g of 0.5% nitric acid solution into the PP bottle, heat it in a 90℃ oven for 30min, add 91.195g of ultrapure water after cooling, and the concentration of this standard solution is 30.00ppm.
[0082] Weigh 0.665g of the mother liquor of the standard solution into a 250ml PP bottle, add 10.223g of 0.5% nitric acid solution into the PP bottle, heat it in a 90℃ oven for 30min, add 89.063g of ultrapure water after cooling, and the concentration of this standard solution is 20.09ppm.
[0083] Weigh 0.345g of the mother liquor of the standard solution into a 250ml PP bottle, add 10.017g of 0.5% nitric acid solution into the PP bottle, heat it in a 90℃ oven for 30min, add 93.222g of ultrapure water after cooling, and the concentration of this standard solution is 10.02ppm.
[0084] The eluent regeneration solution was connected to the anion chromatogram, and the chromatographic column was selected as Thermo AS22 (4*250mm). Samples 25#-29# were tested on the anion chromatogram and a standard solution with a suitable concentration was selected.
[0085] According to the formula The content of 1-propyl cyclic phosphoric anhydride in the lithium-ion battery electrolyte to be tested was obtained by single-standard calibration; the final results are listed in Table 6.
[0086] Table 6
[0087]
[0088] From the data in Table 6, it can be seen that the method for determining the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte of the present invention has good determination data accuracy. Therefore, the method can accurately detect the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte.
[0089] The advantages of the present invention are simple steps, convenience, high accuracy and good stability, which greatly improves the efficiency of determining 1-propyl cyclic phosphoric anhydride in lithium ion battery electrolyte and provides reliable guarantee for the quality of lithium ion batteries.
Claims
1. The determination of the content of 1-propyl cyclic phosphoric anhydride in the electrolyte of a lithium ion battery comprises the following steps:
1. Prepare the sample solution to be tested: take the lithium ion battery electrolyte to be tested and perform pretreatment, the steps include: add the pretreatment solution, the pretreatment solution is a nitric acid aqueous solution with a mass fraction of 0.3% to 0.5%, heat at 60°C to 100°C for 10 to 60 minutes, and dilute with water to obtain the sample solution to be tested after the pretreatment is completed; 2. Prepare the standard solution: take 1-propyl cyclic phosphoric anhydride diethyl carbonate solution, add a simple formula lithium ion battery electrolyte, the simple formula lithium ion battery electrolyte only contains an organic solvent and lithium hexafluorophosphate, stir evenly to obtain a standard solution mother liquor, and refrigerate the standard solution mother liquor; take the standard solution mother liquor, perform the same pretreatment steps as when preparing the sample solution to be tested, and then dilute with water to obtain a standard solution, the concentration of the standard solution is the theoretical concentration value of the sample solution to be tested ±3 ppm; 3. Use an anion chromatograph, the instrument conditions include: the eluent uses Na2CO3 and NaHCO3 with contents of 2.4 mmol / L to 3.6 mmol / L acetonitrile water system, wherein the volume ratio of water to acetonitrile is 3:1; concentrated sulfuric acid is used as the regeneration solution; the sample solution to be tested and the standard solution are measured respectively, and the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte to be tested is calculated by the following formula according to the peak time and the peak area, and the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte to be tested is obtained by single standard calibration; Wherein X is the content of 1-propyl cyclic phosphoric anhydride in the lithium ion battery electrolyte to be tested; A2 is the peak area of 1-propyl cyclic phosphoric anhydride in the sample solution to be tested; A1 is the peak area of 1-propyl cyclic phosphoric anhydride in the standard solution; C2 is the content of 1-propyl cyclic phosphoric anhydride in the standard solution, ppm; B is the dilution factor of the lithium-ion battery electrolyte to be tested when preparing the sample solution to be tested; 10000 is a constant.
2. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: The preparation method of the eluent includes: first preparing an aqueous solution with Na2CO3 and NaHCO3 contents of 2.4 mmol / L to 3.6 mmol / L, filtering it with a 0.45 μm filter membrane, and then mixing it with acetonitrile filtered with a 0.45 μm filter membrane at a volume ratio of 3:1, and performing ultrasonic degassing for later use.
3. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: After the standard solution stock solution is prepared, it should be refrigerated and allowed to stand at 0℃~5℃.
4. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: In the pretreatment step, the heating temperature was 90°C.
5. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: When preparing the standard solution, the specific preparation steps of the standard solution mother liquor include: taking (0.6±0.05) g of 1-propyl cyclic phosphoric anhydride diethyl carbonate solution with a mass fraction of 47% to 53% from a 250 ml pp bottle, adding the simplified formula lithium ion battery electrolyte to (100±1) g, and stirring evenly to obtain the standard solution mother liquor.
6. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: The specific steps for preparing the sample solution to be tested include: taking (1±0.05) g of the lithium-ion battery electrolyte to be tested into a 250 ml PP bottle, adding the pretreatment solution to (10±0.5) g, closing the lid tightly and heating in an oven, and then adding water to (100±5) g to obtain the sample solution to be tested.
7. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: The pretreatment solution is a 0.5% nitric acid aqueous solution.
8. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, characterized in that: The organic solvent in the simple formula lithium ion battery electrolyte is selected from one of diethyl carbonate, dimethyl carbonate, ethylene carbonate, propylene carbonate and ethyl methyl carbonate.
9. The method for determining the content of 1-propyl cyclic phosphoric anhydride in a lithium ion battery electrolyte according to claim 1, wherein: The concentration of lithium hexafluorophosphate in the simple formula lithium-ion battery electrolyte is (13±5)%.